ADVERTISEMENTS.

Mander Brothers,
Wolverhampton,
ARE

EXPERTS

IN
DIPPING AND
SPRAYING PAINTS.

Industrial
Paints and
Varnishes

BRUSHING
DIPPING
SPRAYING
FLOWING
TUMBLING
DRYING
We specialise in all Paints, Enamels,
Japans, Lacquers, Varnishes and
other materials for the protection
and decoration of Industrial Products
of all kinds.
Our clients comprise of the principal
Manufacturers in all Trades,
and the service we are rendering to
them is ready, willing and capable
of caring for your requirements.
Experimental and Research Laboratories
are maintained to assist the
solution of any problem, whilst
there is a wealth of practical
experience to draw upon when
you consult

PINCHIN, JOHNSON & Co., Ltd.

Paint, Varnish, Color & Enamel Manufacturers
Minerva House, Bevis Marks, London, E.C.

TELEGRAMS
PINCHIN, ALD, LONDON."
TELEPHONE
AVENUE 910 (3 lines)

ESTABLISHED 1834

Automatic Finishing of Pianos.
Lowering the Loaded Carrier into the Varnish Tank.

Frontispiece.

Painting by Immersion
and by Compressed Air.

A PRACTICAL HANDBOOK
BY
ARTHUR SEYMOUR JENNINGS, F.I.B.D.,
Editor of "The Decorator" and the "The Decorator Series of Practical
Handbooks," Author of "Commercial Paints and Painting," "Paint and
Colour Mixing," "The Painters' Pocket Book," "House Painting and
Decorating," etc., etc. Member of the Paint and Varnish Society,
The International Society for Testing Materials, etc. Examiner in
Painters' and Decorators' Work to the City and Guilds of
London Institute.
With 150 Illustrations.
London:
Offices of "THE MANAGING ENGINEER,"
93 & 94, Chancery Lane, W.C.

E. & F. N. SPON, Ltd.,
57, Haymarket, London, S.W.
New York:
SPON & CHAMBERLAIN.
123, Liberty Street
1915

PREFACE.

In many industries the application of paint for preservative or ornamental purposes is imperative and the item of expenditure is an important one.

There is abundant evidence to prove that the application of paint, either by means of dipping, spraying or other mechanical means, effects an enormous saving of time over the old method of using brushes, while the coats of paint are more durable and thorough.

This saving of time not only lowers the cost of production to a very considerable extent, but it permits of a large increase in the output.

The process of "flowing-on" enamels and varnishes described in the following pages effects an even greater saving of time in those cases where it is applicable. The extent of this saving can be judged by the fact that a complete coat of enamel can be given to the body of a four-seated touring car in the almost incredibly short time of two minutes!

These processes are used to a very large extent in many industries, particularly those connected with metal work and engineering. In the United States of America and in many parts of the Continent they have reached a high degree of perfection. In Great Britain the adoption of the methods is rapidly increasing.

It is hoped that this book will be found of service to manufacturers who desire to ascertain whether the processes can be economically employed in their particular industry or to those who contemplate putting in a plant for the purpose.

It should also be helpful to those who have not been very successful with a trial plant or who desire to bring an existing plant fully up-to-date in its equipment. And it should be said at once that the few cases of failure which have come to the notice of the author have been found on investigation to be due either to the use of paint unsuitable for the purpose or the adoption of a plant which is unfitted for the object aimed at. Three examples may be given. In one small castings were dipped in black paint, but it was found that "tears," or runs of paint which did not dry properly, often occurred. Here, clearly, the paint was at fault. It was too thick for the purpose and did not dry hard quickly enough. The remedy was obvious.

In another case iron casements were dipped horizontally in a shallow paint tank and the time involved in lowering them to obtain a complete immersion was considerable. In this case the shape and size of the tank were not suitable. It should have been deep and narrow, so that the casements could be dipped vertically. The idea that the paint would "settle out" if a deep tank were used was shown to be erroneous.

In a third case spraying had been tried for coating metal casements, when it was found that the saving effected in time was more than counter-balanced by the waste of paint. Of course, spraying was not suitable for a job of this kind, the surface to be covered being so very narrow. Such work is done most successfully by dipping.

The degree of perfection to which the process of dipping has been carried in America is indicated by the fact that it is largely employed for piano cases and many other articles requiring a perfect varnish finish. This process is fully described in these pages and has been successfully carried on for some years. This fact demonstrates very clearly the possibilities of painting and varnishing by immersion.

All the principal appliances used for spraying paint, lacquer, enamel, varnish and similar liquids have been described at length, but no attempt has been made to prove that any one appliance is superior to another. The details of each apparatus are given, and for the convenience of the reader, the manufacturer's name and address. It is suggested that those who contemplate the adoption of paint dipping, or spraying, should get into touch with all these firms, and carefully investigate their respective merits before coming to a decision.

The services of an expert will usually be found desirable, for, although in engineering works much of the necessary apparatus and accessories may be made on the premises, the exact details, such as the kind of paint and the exact design suitable for the particular purpose, are largely matters to be decided upon in the light of experience.

ARTHUR S. JENNINGS.

365, Birkbeck Bank Chambers,
High Holborn, W.C.

August, 1915.

CONTENTS.

LIST OF ILLUSTRATIONS.

CHAPTER I.

INTRODUCTION.

Until recent years, it appears to have been generally supposed that paint used for either the protection or ornamentation of various surfaces must necessarily be applied by means of painters' brushes made of hog's bristles. But it has been clearly demonstrated during the past few years that the application of the paint may be made by means of either total immersion of the article to be painted in a tank or by spraying the paint on to the surface with the aid of compressed air. The rapid increase in the use of both processes is principally due to the immense saving of time which is effected, and this may be approximately estimated at from five to nine-tenths. In other words, one man can do the work of from five to ten men, or even more. To put it another way, if a piece of work costs 20s. for labour in painting by the old process, it may be safely assumed that it can be done by dipping or spraying at a cost of from two to four shillings.

The question will at once suggest itself: "Is paint applied by dipping and spraying as durable as that applied by the brush?" As the paint in the greater part of work of this character is used solely for protective purposes, the question is clearly one of considerable importance. The answer to the question is that when properly prepared paint is used, both methods give an equal, or even better result from the point of view of durability than that which would be obtained if a painter's brush was employed, while, in the case of painting by immersion or by spraying, the paint finds its way into places which a brush could not reach, such as open joints of a waggon, the intricate parts of certain agricultural machinery, the inside of small metal boxes, etc.

Both methods are successfully employed in practically every branch of the engineering, metal and many other trades. Heavy steel sheets may be dipped provided that adequate plant is employed for lowering and raising them into the tank, or they may be sprayed without much difficulty. Children's toys (to take the other extreme), costing less than a penny each, may also be economically painted by dipping. Speaking generally, anything large or small which can be handled or moved by lifting machinery or on a turn table, can be painted by either one process or the other. For example, a hundred or so of very small iron castings, or wrought iron ware, may be placed in a wire basket and dipped together in a few seconds, or the body of a motor car, or parts of a bicycle, can be painted by spraying in a fraction of the time it would take to do the work by means of brushes.

Thus far the processes are not much used in house painting, excepting for the first or priming coat, before the work is fixed in position, but certain types of the simpler form of spraying machines are employed with great advantage in applying lime white or whitewash to rough walls of factories, etc. In this case, a far better job is produced in one-tenth of the time. The whitewash, when sprayed on, enters and covers the open joints and inequalities of surface in a complete manner, which would be impossible were a brush used.

On the next page is a list of some of the principal purposes for which these methods are at present used, and these are being constantly added to. It is not too much to say that in any industry in which paints are used, one or other of the methods, or both in conjunction, may be employed with very great advantage in a saving of time.

An erroneous idea prevails in some quarters that to install a paint dipping or a paint spraying plant will involve a considerable expenditure. As a matter of fact, if the work is of a simple character, and the articles to be dealt with small, an expenditure of something like £25 will be sufficient for the purpose. For example, a small tank, with a draining board attached, would cost less than the sum mentioned, even when the overhanging plant was included. As such work is usually done in engineering shops, the lifting apparatus and the rails, can easily be made on the premises. In some cases the lifting plant even might be dispensed with, and the articles, such as paint cans, could be dipped by hand. A spraying plant need not be expensive, and £25 to £40 will cover the expense of spraying apparatus, compressor for air spray, exhaust and everything else. This, however, refers to a small plant. More extensive installations would, of course, cost very much more, but whatever they may cost, it may be accepted as a fact that, within reasonable limits, the outlay will be fully returned in two or three years' working at most.

In the following pages an attempt has been made to cover the whole subject of painting by mechanical means. Many plants are described and illustrated, and some lengthy explanation is given of the requirements of different trades or goods. In many cases these have really nothing to do with the painting proper, but success depends upon the system adopted for handling and conveying.

Take, for example, celluloid buttons, which are usually sprayed. They are placed in wire trays made specially for the purpose, the bottom side uppermost. These are first sprayed all over with a spirit paint, and when sufficiently dry to handle, say, in a quarter of an hour, they are all turned over and the top sides are sprayed. The wire trays and a handy cabinet to contain them are the important details in this case.

List of the Principal Products to which Paint
Spraying and Paint Dipping are Applied.

• Acetylene Machines.
• Adding Machines.
• Addressing Machines.
• Advertising Novelties.
• Advertising Signs.
• Aeroplane Work.
• "Agate" Hollow Ware.
• Agricultural Implements.
• Air Compressors.
• Aluminium Goods.
• Antiques, Bric-a-brac.
• Architectural Brass Works.
• Architectural Iron Works.
• Art Glasses and Mirrors.
• Artificial Flowers.
• Artificial Jewellery.
• Artificial Marble.
• Artificial Limbs.
• Artistic Statuaries.
• Automatic Vending Machines.
• Automobile Lamps.
• Automobile Licences and Number Plates.
• Automobile Parts.
• Automobile Parts and Motor Bodies.
• Automobile Supplies
• Automobile Tyres.
• Automobile Tops and Canopies.
• Axes.
• Baby Carriages.
• Badges.
• Banners and Flags.
• Bar Fixtures.
• Barber Equipment.
• Barrels.
• Barrows.
• Basket and Rattan Ware.
• Bath Room Sundries.
• Baths.
• Bed Springs.
• Bedsteads (Iron).
• Bedsteads (Sheet Metal).
• Beer Pumps.
• Bells.
• Bicycles.
• Billiard Tables.
• Bird Cages.
• Blocks and Falls.
• Blowers.
• Boats.
• Bobbins and Spools.
• Boiler Work.
• Book Cases.
• Boxes, Cigar.
• Bowling Alleys.
• Boxes, Mail.
• Brass Bedsteads.
• Brass Goods.
• Broom Heads and Handles.
• Brushes.
• Buckles and Snaps.
• Builders' Hardware.
• Burial Caskets.
• Buttons (metal).
• Cabinet Hardware.
• Cabinets.
• Cameras.
• Candies and Confectionery.
• Canners, Vegetables and Fruit.
• Canoes.
• Cans.
• Cars.
• Carpets.
• Carpet Sweepers.
• Carriages.
• Carriage Hardware.
• Casements (metal).
• Cartridges.
• Cash Registers.
• Cash Carriers.
• Celluloid Sheets.
• Chairs (metal).
• Children's Carriages.
• China and Crockery.
• Church and Lodge Goods.
• Church and School Furniture.
• Churns.
• Clocks.
• Colour Specimens.
• Constructional Ironwork.
• Corset Steels.
• Coffins and Caskets.
• Couches.
• Cream Separators.
• Curtain Poles.
• Cutlery.
• Cycles.
• Cycle parts.
• Desks (metal).
• Display Fixtures.
• Dolls.
• Doors.
• Drills.
• Dynamos.
• Edge Tools.
• Electric Fixtures.
• Electrical Apparatus.
• Electrical Supplies.
• Electro Platers.
• Enamelled Metal Goods.
• Enamelled Ware.
• Engines.
• Etching (metal).
• Factory Fittings.
• Fancy Baskets.
• Fans.
• Fenders.
• Filing Cabinets.
• Firearms.
• Fire Extinguishers.
• Fishing Rods.
• Fixtures, Display.
• Foundries.
• Fountains, Soda.
• Furniture (metal).
• Garden Implements.
• Gas Apparatus.
• Gas Cookers.
• Gas Engines.
• Gas Fires.
• Gas Fixtures.
• Gas Meters.
• Gas and Gasolene Stoves
• Golf Clubs.
• Grates and Mantels.
• Gramophones.
• Grille Work.
• Hats, Straw.
• Hair Pins.
• Hames.
• Handles.
• Harness Trim.
• Harrows.
• Hardware.
• Hollow Ware.
• Hooks and Eyes.
• Horns.
• Incandescent Lamps.
• Japanned Goods.
• Jewellery.
• Kegs and Pails.
• Kitchen Cabinets.
• Kitchen Utensils.
• Knitting Machines.
• Lacing Studs.
• Lamps and Lanterns.
• Lasts.
• Lawn Mowers.
• Lead Pencils.
• Leather Work.
• Letter Files.
• Locks.
• Lockers (metal).
• Looms.
• Locomotives.
• Machinery.
• Malleable Castings.
• Mathematical Instruments.
• Meat Safes.
• Metal Spinners.
• Model Makers.
• Motors.
• Motor Cycles.
• Musical Instruments.
• Novelties.
• Office Furniture.
• Optical Instruments.
• Ornamental Ironwork.
• Pattern Makers.
• Pen Holders.
• Phonographs.
• Physical Supplies.
• Piano Plates.
• Pianos and Organs.
• Picture Frames.
• Pins.
• Plated Ware.
• Ploughs.
• Plumbers' Supplies.
• Porcelain Goods.
• Projectiles.
• Pulleys (metal).
• Pumps.
• Radiators (auto).
• Railway Carriages.
• Rakes.
• Refrigerators.
• Regalia.
• Rubber Goods.
• Rules and Levels.
• Saddlery Hardware.
• Safes.
• Safe Deposit Vaults.
• Sashes (metal).
• Scales.
• Screens (metal).
• Sewing Machines.
• Shoe Buttons.
• Show Cases.
• Side Cars.
• Signs, Enamelled.
• Silverware.
• Sleds and Sleighs.
• Soda Fountains.
• Sporting Goods.
• Steel Stampings.
• Stoves (gas).
• Slate, Enamelled.
• Statuary.
• Steam Gauges.
• Steel Castings.
• Street Railway Companies.
• Surgical Supplies.
• Switchboards.
• Tables.
• Tanks.
• Telephones.
• Telephone Supplies.
• Textile Machinery.
• Tinwares.
• Thermometers.
• Tools.
• Toys.
• Trunk Hardware.
• Typewriters.
• Vacuum Cleaners.
• Vending Machines.
• Veneers.
• Ventilators.
• Wagons.
• Wall Papers.
• Washing Machines.
• Watering Cans.
• Weighing Machines.
• Wheels.
• Willow Ware.
• Wire Cloth.
• Wire Mattresses.
• Wire Work.
• Wringers.

In addition to the above, paint is applied by spraying for many artistic purposes, such as for show cards, photographic work, lithography, church decoration, etc. These are referred to in another chapter.

CHAPTER II.

Painting by Immersion.

The process of painting various articles by dipping them bodily into specially prepared paint contained in a tank or other receptacle is a very old idea. It has, however, developed considerably in late years, and is now largely employed in many industries, particularly in the finishing of agricultural implements of various kinds, iron work and a hundred and one other articles. It is sometimes used in conjunction with paint spraying; that is to say, the first coat or coats may be put on by immersing the article to be painted in the paint, or varnish, and the final coat of enamel or varnish may be put on by means of a spray. In some cases, the final coat is applied by means of brushes in the ordinary manner.

Perhaps the simplest form of paint dipping is that applied to various articles, such as bolts, rings and small parts, which are placed in a wire basket and plunged into the paint. The basket is then hung up for a quarter of an hour or so to drain, and afterwards in another place, until such time as the paint becomes hard.

Another familiar example of painting by dipping is that of ordinary tapered cans, such as those which are used to contain varnish, etc. In this case, a piece of wood is introduced into the neck, the can is immersed in the paint up to almost the top of the neck, and is then placed upside down to drain and to dry. A paint which dries with a gloss is usually employed for this purpose, and it may be remarked that a good deal of this work is now done by spraying; in fact, a great deal of difference of opinion exists as to the respective merits of the two processes for this particular purpose.

Fig 1.—Cross Section Through Paint Tank.

Going a step farther, we come to the consideration of articles such as iron sashes and casements, parts of staircases, etc., which may be dipped into a tank containing, say, five to ten gallons or so. Such tanks are usually made to slant at the bottom in order to facilitate cleaning when necessary. Adjacent to them is provided a platform, usually lined with sheet iron upon which the paint can drip after the articles are removed from the tank, and a system of overhead rails for moving the articles from one part of the works to another. No agitating apparatus for the paint is required, but after the tank has been used for some time, say, for example, at the week-end, it is necessary to stir it up by means of a pole before the work commences. As a matter of fact, the articles being plunged in the tank, and their withdrawal, in itself stirs the paint sufficiently for the purpose.

In dealing with the larger-sized articles which are to be painted, such as reaping machines, the construction of the tank which may hold several tons of paint is naturally of a more elaborate character. Such a plant will consist, first, of the tank itself; next, the system of overhead railing; third, the apparatus upon which the articles to be painted are hung; and fourth, the hoists for lowering and raising such articles into and from the tank. It will be convenient to consider these parts which go to form a complete installation under their several heads, taking a more elaborate plant by way of example, it being understood that the plant may be simpler in form when the size of the articles to be painted is small, or under other circumstances, such as will be presently suggested.

The Tank.

Stirrers and Blinds for Paint Dipping Tank. Fig 2.—Plan.
Fig. 3.—Longitudinal Vertical Section.

There are two forms of special tanks in general use, one having at the bottom paddles for agitating purposes, and the other worms provided with the same object. Fig. 1. shows a cross section of a tank made on the McLennan patented system. In this two series of paddles revolving in opposite directions are provided, and above them is an appliance which may be likened to a horizontal venetian blind, consisting of iron laths, which are nearly horizontal when closed, forming a platform upon which the paint can settle, and vertical when open. This blind is left open when the tank is in use, and is closed when it is at rest. The illustration gives the dimensions of the parts, although these, of course, will be varied according to circumstances. Above the blind is sometimes a grating, which, together with the blind, form a protection to the agitating gear from articles dropped into the tank by mistake, the two together preventing the heavy, pigment in the paint from clogging the paddles when the agitating gear has been stopped for some time. Figs. 2 and 3 show respectively longitudinal plan and section, from which the construction will be clear.

Messrs. Wilkinson, Heywood & Clark, Ltd., of Poplar, who own the McLennan patents, in a little book, entitled "Painting by Immersion," state that there were certain disadvantages in the design of this tank, inasmuch as should it become necessary to remove or repair the paddles, it would be necessary to empty the tank and bodily remove the parts. They have, therefore, a new design, which is shown in Fig. 4, in which this remedy is overcome. The agitating gear, in this case, is on a sub-frame, separate and independent from the tank itself. The drive is in the tank, and is taken by means of a claw clutch through a right angled bevel to the agitating shaft. This design has proved very satisfactory for small tanks. For very large tanks a gear is recommended in which the agitating gear is enlarged and the shafting is supported or stiffened to prevent whipping. This entails a design of some special bearing, which should be paint proof and oil proof, for the reason that the bearing is immersed in the paint itself. In Fig. 5 is shown drawings of this bearing, on which the firm named hold patents. The perfected plants now consist of a tank with an independent and removable chassis frame, on which are mounted the Venetian blind arrangements, already mentioned, together with the agitating gear, which consists of either one, two, or more parallel shafts, mounted on parallel gear, as shown in Fig. 6.

These shafts are held on the sub-frame with the patent bearings already referred to, and the drive is transmitted through the bevel gear encased in a special gear box, which is equally oil and paint proof and self-lubricating. It will readily be seen that with this plant it is an easy matter to withdraw the driving gear and lift the sub-frame bodily out, without in any way disturbing the paint in the tank. The tank, therefore, can be buried nearly flush in the ground, embedded in concrete, and need never be disturbed. In case of emergency, and when painting is continuous throughout the year, it is recommended that the consumer should keep a complete spare chassis for use when occasion requires.

Fig. 4.—Design for Tank for Painting Steel Sheets.

Fig. 5.—Details of Paint-Proof Bearings and Gear Box.

Fig. 6.—Details of Sub-frame, Shafting and Driving Gear for Tank Designed for Implement Manufacturers.

Whatever the construction of the tank itself may be, and whether or not it is provided with agitating apparatus, it is generally found most convenient to build it with the top nearly level with the floor. It is advisable to provide iron doors or covers to close the tank in when out of use so as to prevent excessive evaporation and also for use in case of fire. These doors or covers should therefore be actuated by levers or other suitable appliance which may be put in motion at a point some distance from the tank itself, for while the paint is not very liable to catch light, an accident may cause it to do so, particularly when electricity is used in the works, and the closing of properly constructed doors will quickly subdue fire as far as the tank itself is concerned by shutting off access of the air. The usual plan followed is to provide wide strips of thick felt attached to the doors in proper position so that when the doors are closed the contact will be thorough and the tank itself be practically sealed.

When agitators form part of the apparatus it is not necessary to buy the paint ready mixed for use, as it may be introduced into the tank in thin paste form; the necessary thinners such as white spirit can be added and the agitating apparatus slowly revolving will quickly mix the parts together and render the paint suitable for use.

It will be understood that the form of tank above described may be very considerably modified according to circumstances. In very simple paint dipping, such as is required for small articles, casements, etc., the agitating apparatus may be wholly dispensed with, while in other cases, the shutter-like arrangement above mentioned may be omitted and the agitator may consist of a worm with a screen above to protect the parts from pieces which may accidentally fall in.

Fig. 7.—General Lay-out of a Three-tank Plant Designed for the Use of an Agricultural Implement Maker, Using Three Colours in this Instance, Red, Green and Blue.

The Rails and Hanging Apparatus.

Fig. 8.—Joist and Wheels Supporting Hanger.

These two details may be conveniently considered together, and it should be stated at once here again a great deal of difference of opinion exists as to what system is the best. It should, however, be clearly understood that upon the system of railing a great deal of the success depends. The object, of course, to be attained is that of handling a large number of parts with as little labour as possible. With this object, a complete system of overhead rails, commencing with the finishing shops, leading to the paint tank, and thence to storage or delivery departments, should be carefully thought out, always remembering that the growth of a business may necessitate the erection of additional buildings from time to time and provision made accordingly. One of the simplest and best forms of rails is an H section joist with two wheels on either side as shown in Fig. 8. In other cases an L rolled joist is used, the railing part being on the vertical flange while the horizontal flange is connected with rods fixed to the upper part of the building. One method which is used quite successfully is to employ hooks as shown in Fig. 9. These run over rails which are lubricated with vaseline, and in this case the rails are usually slightly inclined. In very large works, however, where a considerable length of rail is employed this inclination might be inconvenient, as the rails would go too near the ground. In all cases horizontal rails are found in practice to be the most convenient, but an installation requires careful consideration from all points of view and no general rules can be laid down.

Hanging after Dipping or Spraying.

A practical point of more importance than might be supposed, at first sight, is to avoid hanging articles very close together after they have been painted or enamelled, either by dipping or spraying. The reason is that if they are hung quite close together the turpentine or volatile thinner used in the paint may affect part of the adjacent surface, and cause a diminished gloss.

Fig. 9.—Hook for Hanging.

This point was brought to light in the case of one manufacturer who was painting varnish cans by dipping. They were hung up to dry quite close together—in fact, almost touching. When dry, it was noticed that, instead of being nice and glossy all over, one side was somewhat dull. The explanation appeared to be that the turpentine fumes affected the paint in drying, and this was proved to be true, as when the cans were placed farther apart the trouble ceased.

Hoists.

The hoists used will depend upon the size and weight of the objects that are to be dipped. In some cases they may be dispensed with altogether and the dipping can be done by hand.

Fig. 15.—A Typical Hoist for Use in Painting by Immersion.

In cases where the space is confined, it is sometimes desirable to use hoists in the form of wall crabs, and a few of these made by the London Hoist Machinery Co., Ltd., 103, Worship Street, E.C., are illustrated in Figs. 10 to 14. The hoist shown in Fig. 10 will lift 10 cwt. with slow speed on the left-hand side, and 3 cwt. on the right-hand side with a quick speed of 13 feet per minute. This form can be made lower by brake if desired. The little crab shown in Fig. 11 deals with weights of 1 cwt. at a speed of 60 feet per minute, while that shown in Fig. 12 is also a quick gear, lifting 3 cwt. at 13 feet per minute. The other illustrations are self-explanatory.

Fig. 15 shows a typical hoist which may be regarded as an ideal installation for the work, and the idea can be adapted to either large or small works as required. The installation consists of an overhead track with a movable portion over the dipping tank. The goods to be dipped are hung on the trolleys and run one by one on to the movable portion of the track over the tank. There is a stop on this portion to prevent the trolley running right over the tank, and the movable portion with the article to be dipped is lowered into the tank, and afterwards raised by means of a hoist. The hoist in this case was driven by pneumatic power. It could, however, in very small installations be a hand hoist worked by the rotary movement of a handle, or in other large installations a quick moving electric hoist.

After the article is dipped and the movable portion raised by the hoist to its correct position in the track of the runway, the trolley is run off the movable portion on to the track beyond the tank, and left there to dry.

These overhead runways can be made to suit loads from 2½ cwts. up to 10 tons, so that the system covers all classes of work, since it is seldom that it would be necessary to dip articles weighing more than 10 tons.

Fig. 16 shows a Morris standard electric trolley hoist suitable for lifting up to, say, 5 or 6 tons. Both of the foregoing hoists are made by Messrs. Herbert Morris, Ltd., of Loughborough, to whom the author is indebted for these illustrations.

In Fig. 17 is shown another type of trolley hoist suitable for lifting heavy weights.

The number of Coats of Paint to be Given.

An important consideration both in paint immersion and paint spraying is the number of coats of paint which should be given in order to produce the required appearance and ensure durability. This must necessarily depend upon the use to which the article to be painted is to be put, and it will also depend upon the appearance. In paint spraying it is clear that any thickness of paint required could be obtained by continuing the operation of spraying, but it has been found in practice that it is not desirable to continue the application of the paint beyond the point when every part of the surface is completely covered. It is a well-known fact that three thin coats of paint applied separately will prove more durable than two thick coats, even if the quantity of paint used in the two cases is identical. The same is true to a great extent when the paint is sprayed on. When it is applied by dipping another important element enters into consideration, and that is, thin coats are a practical necessity, because if an attempt was made to make the coat thick it would inevitably result in unsightly runs, fat edges, etc., which would wholly spoil the work. Where the object is only that of a temporary protection, as in the case of iron castings, a single coat will usually suffice, because the castings when fixed in position will be painted with the building in the ordinary way.

Sometimes a priming or first coat of paint is given by dipping, and the following coats are applied by brushes or by spraying. There appears to be some idea that when paint is applied by brushes it is forced into the pores of the wood and therefore holds better; as a matter of fact, in a well-designed paint the thinners will penetrate the wood and no particular force is necessary; but if it should be, it will be certainly supplied by the spraying process.

Advantages of the Dipping Process.

The advantages of applying paint, japan, enamel, or varnish by the process of immersion are obvious. The saving of time is the chief advantage, and this will be in most cases very considerable. For instance, a complete wagon can be painted by dipping in a very few minutes, while large and intricate agricultural machines may be painted in the same way in a fifth part of the time it would take to spray them, and probably a twentieth part of the time it would take to do the work by hand.

There is another advantage which should be mentioned when paint dipping is compared with spraying. In the latter, an outfit consisting of sprayer, air compressor, exhaust, cabinet, etc., are all necessary. In dipping, however, the apparatus may in many cases be of the simplest character. For example, in painting bedsteads all that is necessary is a narrow but deep tank containing the paint, into which the bedstead may be plunged by hand and then hung up to drip over a metal-lined floor.

Fig. 16.—A Morris Standard Electric Trolley Hoist.

In Birmingham, hundreds of iron bedsteads are dipped in this way every day. The head or foot of the bedstead is taken in the two hands of the operator, dipped into a tank of black japan, and immediately hung up on a travelling chair, which slowly carries it across the room to the oven, the superfluous paint dripping off during the process.

In another chapter will be found the advantages which the process of spraying has over dipping. A decision as to which is the best system to adopt for any particular purpose can only be determined after due consideration has been given to all the circumstances bearing upon the work to be done.

It may be pointed out in this connection that the process of painting called "flowing on," which is fully described on another page, is in effect only a modification of dipping. As a motor body, for instance, cannot be plunged into a paint tank because the inside is not to be painted, the paint is literally poured over the surface, and the effect is exactly the same.

Protecting Parts Not to be Painted.

It frequently happens in paint dipping that certain parts of a machine or other article that is desired to be coated with paint is to be left unpainted, and the problem is how to effect this most economically. The method usually employed is to cover the parts, such as name plates, bright portions of a machine, etc. with vaseline. When the article is dipped the paint covers this as well as the other parts, and after the paint is dry the vaseline and the paint on it can be easily wiped off and the surface beneath it will be found to be quite clean.

Preparing Woodwork Before Painting.

Previous to the priming coat of paint being applied to any article made of pine or other wood containing knots it is necessary to protect such knots by applying one or two coats of a liquid known in the trade as "knotting." If this were not done the rosin which exudes more or less from the knots would penetrate the paint, discolour it and give a very unsightly appearance.

The best knotting consists of shellac dissolved in alcohol, usually in the form of methylated spirits; in other words, it is shellac spirit varnish. Many inferior grades, however, are sold in which the shellac is adulterated with rosin or other substances, while the alcohol is sometimes replaced wholly or in part with naphtha. These inferior qualities of knotting should never be used, as they are very likely indeed to cause trouble and spoil the whole job.

Although the parts of machines such as agricultural implements are usually made of selected and well-seasoned timber, it sometimes happens that portions of the work are found to be more or less sappy. This should also be coated with knotting, as otherwise they will absorb the paint to too great an extent and the priming coat will not be uniform.

In passing, it may be observed that a coat of shellac varnish—a term, as already explained, which is synonymous with knotting—is very useful as an undercoat whenever there is an excess of rosin as in pitch pine. It is also used to stop suction on plaster ornaments which are finished in imitation bronze, and which may successfully be used over tar or tar spots which it is desired to paint.

It is very important that knotting be applied in quite thin coats, and it is for this reason that usually two coats are given. If it is too thick it fails to dry properly. Thick knotting may be used if it be well brushed out, but this is almost impossible in applying it to the knots of ordinary woodwork which are merely "dabbed" with the end of the brush; moreover, such work is usually done by piece work, hence two coats are much safer to use.

Filler For Iron.

It is sometimes necessary before dipping or spraying cast iron work to fill up sand flaws and inequalities. This may be effectually done by using a filler prepared as follows: Mix together equal parts of genuine red lead and gilders' whiting and add two parts of boiled linseed oil and one part of goldsize. It will be found most effective to mix the two liquids last mentioned before adding them to the dry lead and whiting. Thoroughly mix all together, or, preferably, grind through a mill until the putty-like consistency is obtained. This stopping will dry very hard. It is important to remember that this filler must be mixed in small quantities as required as it rapidly becomes hard, so that if a considerable quantity were made at one time any unused would become spoiled.

Fig. 17.—Electric Hoist Suitable for Heavy Goods.

Another recipe of an entirely different character for a cement or putty for the same purpose is made by mixing one parts of flowers of sulphur, two parts of sal-ammoniac and 80 parts of iron filings and making them into a paste with water. By increasing the proportion of sal-ammoniac the setting is also increased.

Stopping Holes in Woodwork.

However carefully a piece of woodwork may be prepared, there are usually more or less depressions or holes such as those which occur over countersunk nails, and in other places which require to be filled up. The usual stopping for this purpose employed by house painters is a mixture of equal parts of dry whiting and dry white lead, made in the form of putty, with raw linseed oil to which, say, 10 per cent. of boiled oil has been added. A cheaper and quite as effective a stopping, however, can be made by using a material known as "Alabastine," which possesses the advantage of being easily cut down. This material may be also used when mixed to a thinner consistency for priming, but it is not suitable for being applied by dipping, although it may be sprayed. The very best stopping is one such as is used by carriage painters, and is strongly recommended for high-class work. It is supplied both in powder and paste form by all first-class varnish manufacturers, and although the cost is a little higher than that of stopping putty made of whiting and linseed oil, as described, it is well worth the difference.

An excellent filling composition for coach and motor body builders, railway and tramway carriage manufacturers, etc., is that made by the well-known varnish house of Messrs. Wm. Harland & Son, Merton, S.W.

It is especially suitable, obtaining a perfectly level and unyielding groundwork where a fine finish is to be given, either in paint, varnish or enamel. It is made in two colours, grey for dark work and cream for light colours or white, and costs sixpence a pound, or less when bought in quantities.

It effects a great saving of time and labour, being already finely ground into a stiff paste, which only needs the addition of specially prepared thinners to bring it to a proper consistency for use with the brush.

It is most successful and expeditious as well as the most economical process for giving a smooth surface to rough castings—a condition which is, of course, indispensable when these have to be painted and varnished.

For ordinary surfaces of woodwork of a slightly rough or uneven character, two or three coats of the filling composition will suffice to produce, when carefully rubbed down, a perfectly smooth surface of a hard metallic nature, combined with great tenacity and durability.

"Philorite" is another speciality which may be mentioned in this connection. It is manufactured by Messrs. Wilkinson, Heywood and Clark, Ltd., and is a filler made in white and seven colours. This is a great advantage when the finish is to be coloured, as it may save a coat of paint. It can be rubbed smooth without difficulty, and will serve as a perfect ground for enamels and japans, as well as for paint. For use it is thinned out with American turpentine to the required consistency, say, that of a ready mixed paint. It is brushed on with a stiff bristle brush, and two coats may be safely applied on one day. The last coat can be rubbed down smooth with pumice and water or sandpaper. It may also be used as a knifing paste for defective surfaces.

Rubbing Down.

In many cases the coats of paint, japan or enamel have to be rubbed down between coats in order to produce a perfectly level surface. This is usually done by means of finely powdered pumice stone and water, and it is important to remember that the operation must be done with care so that the rubbing is quite uniform. If a slight gloss is given to the paint the portions which are rubbed down can readily be discerned, as they will have a gloss, and in this way uniformity can be ensured. It is of the utmost importance that all of the powder be washed away before the next coat is applied; if any is left it will mar the job. It may be noted that the work of rubbing down may be done more expeditiously by means of the finest grade of steel wool. On the Continent this is now used exclusively, and it is rapidly gaining favour in Great Britain.

Fig. 18.—Sprayed Show Card.

Fig. 19.—Dipping and Stoving Bedsteads.

CHAPTER III.

Requirements of Different Trades.

The following are a few of the special requirements of different trades as to paint dipping. The details might be lengthened almost indefinitely.

Bedsteads.

The methods adopted for the class of work will, of course, depend upon the quality of the finish required. Cheap bedsteads may be done by dipping in one coat of black japan and stoving at 350° F. In better class work several coats may be applied either by dipping or spraying, and each may be rubbed down after stoving. If a good enamel is used this is unnecessary.

When the work is white several coats—say, at least three—are necessary, for white japans cannot be made which will cover sufficiently in one coat. White lead should not be used in this class of work for the reason that a good deal of handling of parts is necessary, while the rubbing down is sometimes done with glass paper and cause dust, both of which may give rise to lead poisoning. All of the best white japans or enamels are made on a base of zinc oxide or lithopone (zinc sulphide), or a mixture of them.

Collapsible Gates.

This work is usually done by dipping in paint which dries "flat," i.e., without gloss. The colour is, as a rule, black. In fitting and adjusting the work in order that the parts will collapse readily it is necessary to apply a lubricating oil where the rods meet. This lubricating oil is difficult to remove after the adjustment has been completed, and therefore the last coat of paint is usually put on by hand. It is suggested, however, that raw linseed oil might be used instead of lubricating oil, and that this could be wiped off as soon as possible after the adjustment. In such a case the paint could be applied by dipping, as if even a little of the raw linseed oil were not removed it would not interfere with the drying of the paint to any material extent.

Dipping Sewing Machine Parts.

The process employed by a very large firm of American manufacturers is as follows:—

When the castings come from the machine shop they are boiled for 20 minutes in ammonia water to kill the grease (1 of strong ammonia to 20 of water), and are then rinsed in hot water. Any holes or inequalities in the castings are then stopped with a filler made from dry white lead, mixed into a stiff paste with some varnish, brown japan dryers and dry lampblack made quite stiff. When the stopping is hard the castings are dipped into a black metallic coating thinned with 62% benzine to a specific gravity 850. They are then dipped with two coats of finishing japan (sp. gr. 830) flatted with powdered pumice after each coat and leathered off. The parts which are not plated or flatted are given 5 hours stoving at 325° F., and are then rubbed with pumice and carpet pad until flat. Cut out gold transfers are then fixed with transfer varnish and the work is stoved at 185° F. The parts are then sponged and dusted, and are given a good coat of polishing varnish (sp. gr. 950) Finally the work is rubbed down fine with glass paper and pumice powder and then polished with machine oil and rottenstone powder for the iron, or rottenstone and benzine for the tables. The latter, as well as the covers for these, are not usually dipped but brush finished.

Iron Rods.

Fig. 20.—Immersing Mangle Frames.

In most cases, iron and steel rods are best painted by immersion, as the small surface presented would cause too much waste if spraying were attempted. As in most cases of dipping, success depends largely upon the means adopted for handling and dipping a number of rods at one time. Frequently, stoving is required to harden the japan, because a rod is often subjected to considerable wear. Perhaps the best plan to adopt, where the number of rods to be treated warrants the outlay, is to provide mechanism by which the rods are dipped and are at once automatically carried into a stove, and by means of slowly travelling chains, carried out at the other end.

An excellent contrivance for the purpose is in use at the Ford Motor Works, at Manchester. This consists of a vertical oven, heated by gas, and having slowly-moving endless chains running from bottom to top and down again to a point where the rods are discharged on to inclined runners. These rods are passed through a bath of japan, are then taken up by the chain, and, during their progress, are baked. A gear is provided by which the time between the entry of a rod to its discharge may be varied from twenty to ninety minutes, or any period between, according to the purpose for which the rod is to be used and the degree of hardness of the japan required.

Iron Window Frames or Casements.

A long narrow tank, say, from 1 foot 6 inches to 2 feet wide and 15 feet long, is suitable for this class of work, which is usually done in one coat only, and this is quite sufficient to protect the iron until the casement is fixed in position, when it will, of course, receive additional coats by means of a brush in the ordinary way.

It is important that the iron be dipped just as soon as it leaves the finishing shop, and it is necessary that the surface be thoroughly cleaned before the paint is applied, and particularly after all scale is removed. Sometimes the application of the sand blast is necessary for this work, but, as a rule, a vigorous application of suitable wire brushes will suffice.

Another very important provision is a system of overhanging rails on which the sashes or other articles can be run direct from the finishing shop to the paint tank, and thence to any part of the building, from which they may be taken as required for shipment.

The paint used for casements is usually grey, being as a rule made of zinc oxide and lampblack. These pigments, when mixed with a suitable vehicle, are very durable, while, the colour being neutral, it is suitable as an undercoat for green, as well as nearly any other colour which it may be desired to use as a finish. The weight of the paint should be 13 lbs. to the gallon, and it should dry with a semi-gloss. The elevating apparatus need only be of a simple character, and several casements can be suspended and dipped at one time. For this purpose a "hanger" is used, having perforations through which one end of the hooks pass. One form is shown in Fig. 21. By the side of the tank should be a large metal lined floor, say, 20 feet by 15 feet, or even larger, inclined toward the tank. The frames having been plunged into the paint, are at once withdrawn and hung in rows to dry over this floor. The superfluous paint drips on to it and runs back through a screen or sieve into the tank. The latter should be provided with a cover, to be closed in when the work is not being proceeded with.

Fig. 21.—Iron Hanger for Suspending Several Articles to be Dipped Together.

In this class of work it is unnecessary to employ a stirring apparatus provided that the paint is of the right consistency, and an occasional stirring up with a pole after the work has been suspended, say, for example, from Saturday to Monday, will usually be all that is required. As a matter of fact, the lowering and raising of the casements into the paint effectually stirs it up.

Metal Furniture.

Fig. 22.—The Automatic Finishing of Pianos.
Carrier Filled with Six Complete Pianos.

Under this head it is intended to include such articles as deed boxes, lockers, files and other metal goods which are required to be painted both inside and out. An enamel stoving or baking paint is usually employed for the purpose, while the tank must be of sufficient size to accommodate the various articles that are to go into it. Taking a deed box by way of example, a large iron hook, such as is shown in Fig. 32 is placed inside the box so that it is suspended at an angle; the box or boxes are then lowered into the tank and immediately withdrawn after all the superfluous paint runs away, care being taken that the box hangs at a proper angle to permit of this being done. Great care must be taken in this room to exclude all dust, which would considerably mar the work. For this purpose wire netting of the finest mesh should be placed over the windows so as to screen off any dust which might otherwise enter. A system of overhead rails are made, consisting of an L-iron on the top side of which run two rollers to which are attached hanging gears, and is sufficient for the purpose. At least ten minutes should be allowed for these articles to drip over the inclined floor adjacent to the tank, and for safety's sake it is as well to employ a workman with a brush in his hand to go over each piece and remove any tears or runs which may possibly occur. Metal work of the description named is then placed in a stove and baked for three hours at a temperature of 400° F. The paint is frequently green, which is found to be a good serviceable colour and which is attractive in appearance. After the baking the paint is quite hard, and will withstand more or less rough usage. If any ornamental work is required, this is done afterwards, as explained under the head of "Stencilling." The paint employed weighs 13 lbs. to the gallon, and a fine mesh paint strainer must be provided, through which the superfluous paint passes as it drips from the articles on their way to the tank. In this case, as in others, no special stirring apparatus is required, as the comparatively heavy vehicle and the relatively light specific gravity of the pigment employed gives little or no opportunity for any "settling out."

Motor Parts (Metal).

The various parts which go to make up a complete motor car are differently treated according to their shape and size. In most cases, stoving is resorted to, because the enamel or japan is thereby much increased in durability by the hardening which takes place in consequence of the high temperature.

The steel rims of wheels are dipped by hand into a black japan made especially for the purpose. They are hung on hooks and allowed to drain for some minutes, and are then transferred to the stove, where they are subjected to a heat of 320° F. Such parts as ribs, front and rear wings, running boards, shields, etc., are dealt with in the same way.

Previous to dipping, these parts undergo the process known as "pickling," by which scale, grease, etc., is removed so that a perfectly clean surface is presented to receive the japan.

Troughs to catch the drips must be provided, and it is essential that these be kept quite clean, so that the superfluous japan may run through gauze and be pumped back again into the tank to be used again.

Automatic Finishing of Pianos.

The Standard Hydraulic Immersion System.

Any doubt as to the perfection of finish which may be produced by a carefully thought out system of immersion or dipping must be removed by the fact that such a system has been in successful use for some years for the finish of pianos. It need hardly be pointed out that such a finish must necessarily be so well done as to approach perfection.

One firm has made a special study of this subject, viz., the Standard Varnish Co., of London and New York, and their efforts have been most successful.

By this method an absolutely even distribution of varnish is always secured; no part of the piano case is neglected and an enormous reduction in the cost of varnishing is effected. The factory output can be readily increased as desired, as the varnish working force of the factory can do as much or as little work as trade conditions may demand.

The mechanical details have been so perfected that every kind of instrument can be handled satisfactorily.

The excellence of the finishing done in accordance with this system is attributable to a large extent to its mechanical construction. The apparatus used in connection with the Standard method of piano finishing consists, in the first place, of a steel tank for the varnish with an adjustable cover which can be locked when the apparatus is not in operation, a hydraulic lift for raising the work slowly out of the varnish, a small horse-power pump which is operated either by steam pressure or compressed air, and in extreme emergencies where the pressure is not adequate for heavy work, a small motor for operating the pump.

There is also installed an apparatus similar to the automatic sprinkler system. A fusible link or another mechanical device makes it possible to draw off the varnish into a tank outside the main buildings at will, and for protection in case a fire should take place in any other part of the building.

The principal investment for the piano manufacturer is the carriers or racks for holding the separate pieces. The cases are held firmly in the carriers by means of springs which are adjusted for the introductory carrier, or secured by screws in the permanent carrier which is designed for keeping the cases in the carrier until they are ready for rubbing. This latter method saves the labour of handling.

Fig. 23.—Automatic Finishing of Pianos.
Introductory Carrier ready for Parts to be Varnished.

Carriers filled with work to be varnished are raised from the floor, swung directly over the tank, and lowered into the varnish by means of an hydraulic lift. The speed with which the work is raised from the varnish is controlled by a lever conveniently located for the operator.

Once the speed has been determined and the lever set the apparatus requires merely the supervision of an operator, who may devote considerable time to helping his assistants reload another carrier while the one in the tank is emerging. Generally only a limited number of carriers are required.

When the work is to be removed between coats a large percentage can be handled without tack in a short time after it is taken from the varnish.

In the introductory carrier, parts like piano tops, which are finished on all sides, require a little additional care because of the difficulty of handling. This contingency is provided for by the use of special head pieces.

In emergencies, for rushing out an extra quantity of work, carriers holding falls, frames and small parts may be immersed in one-half the interval usually required.

For example, these carriers can be withdrawn in from fifteen to twenty minutes, whereas for carriers including sides from twenty-five to thirty minutes are required. The carriers are equipped with head pieces adjustable to meet all peculiar local factory requirements. In fact, these carriers can be constructed by the manufacturer to meet all his demands.

The number of carriers necessary depends entirely upon the volume of work to be handled. But it is desirable, when possible, to have a sufficient number of carriers to hold all the work until the varnish is sufficiently dry for rubbing. In this way a tremendous amount of labour and time is saved.

Permanent carriers, in which the work has been secured by ordinary screws, have been constructed by some manufacturers at an unusually low cost by their own machinists in their own factories.

The work in the carriers can be easily dusted by means of air-bellows or a compressed air-blower. Work finished in this manner is so clean that the usual sanding is not necessary and a considerable amount of labour thereby saved.

That the Standard hydraulic immersion system of automatic finishing of pianos has distinct advantages over the ordinary hand process is obvious even to the casual observer. Among the numerous advantages which have been effected the following seem to be worthy of special consideration:

It constitutes practically the factory's entire varnishing force.

Its use insures an even coat, free from imperfections.

Coating both sides of the work preserves the cases considerably from shrinking and warping. A great deal of labour is saved by varnishing both sides at once.

It requires very little more varnish than the old, slow, hand method as there is no waste from brushes and pots and absolutely no dripping outside the tank.

The elasticity of the Standard system of piano varnishing eliminates the necessity of additions and reductions to the working force.

The cleanness and evenness of the finish virtually makes every coat a flowing coat. The amount of time and effort saved in the rubbing and polishing is tremendous, and the finish obtained is much finer, due to the absence of uneven coating and the blemishes of pinholing and dust.

Carriers containing six complete pianos each, at an average interval of one half-hour, will enable the factory to turn out 108 pianos with one coating during a nine-hour working day.

Carriers containing eight complete pianos would handle 144 pianos a day. A lift sufficiently strong to accomplish any demand placed upon it can be installed to immerse as many carriers at once as will be necessary.

A smaller carrier containing four pianos can be installed for the manufacturer with a small output of pianos, which by the very nature of its construction is handled more readily than the larger carrier.

In coating both sides of the work a decided protection against shrinking and warping has been provided. In fact many manufacturers are taking this precaution by brushing both sides of the work. By the Standard method the work is automatically coated on both sides at the same time.

Very little more varnish (not more than 5%) is required by the Standard system than by the hand method. The inventors' own experiments, as well as the daily use of the system by manufacturers, shows that more varnish is wasted about the varnishing room than is required by the immersion system to coat the unfinished side of the work. With this method, all of the small amount of varnish that drips off falls back into the tank.

Fig. 24.—Lowering Piano Cases into the Varnish Tank.

Fig. 25.—Piano Cases nearly Immersed.

Fig. 26.—Piano Cases Wholly Immersed.

One of the most difficult tasks of the finishing room foreman is to be certain that the proper reduction is made for the first and other undercoats. This is entirely eliminated with the use of the Standard system of piano finishing. This process alone makes it possible to apply a minimum quantity of varnish sufficient to withstand the strain of rubbing and polishing. This lessens the possibility of shrinking and cracking which excessive varnish coats applied by brush involves. The slower the speed of the lift, the less varnish is applied to the work, consequently there is a gradual regulation of the amount of varnish for the separate coats.

Fig. 27.—Piano Cases about to be Dipped.

The foregoing description, together with the accompanying illustrations, will enable the reader to understand the general method adopted. It should be added that it is applicable to many other articles besides piano cases.

The system described was invented and is controlled by the Standard Varnish Company of London and New York.

Wheels.

An extremely ingenious but effective machine for coating hickory wheels with paint or japan is in use at the works of the Ford Motor Company, Trafford Park, Manchester. It consists of a stationary cylindrical vessel of exactly the right size to receive a wheel, which, being placed in position, is at once lowered into a tank containing the japan. Here it is made to revolve very rapidly, by which means the japan is thoroughly distributed over every part. Hickory, being a hard and comparatively non-absorbent wood, the japan might give too thick a coating if dipped and left to dry in the ordinary way. To prevent this, the wheel, while still revolving very rapidly, is mechanically lifted out of the japan, and is held just above it, where it continues to spin. This has the effect of throwing off the superfluous japan by centrifugal force. The cylindrical sides of the apparatus catch the japan, and it runs down into the tank below. The wheels are then taken out by a man, who wears gloves, are stacked on edge in rows to dry, and, after an hour or so, they receive a second coat. After twenty-four hours, or less, they are ready for use.

The advantage of rapidly revolving the wheels is that anything in the nature of a drip is entirely eliminated. This machine can deal with 300 wheels an hour, so rapid is the process. At the present time the Ford Works are using 2,000 wheels a week.

Some Typical Plants.

In gathering information of up-to-date character to include in this book the author has visited various parts of the country, and through the courtesy of the firms mentioned below has examined the plants used successfully for the treatment of many different goods. The following is a brief description of some of the plants inspected, although it by no means exhausts the list:—

Carriage Department, Woolwich Arsenal.

Fig. 28.—Dipping a Coach Body at Woolwich Arsenal.

Fig. 29.—General View of Paint Dipping Room at Woolwich Arsenal.

The plant for painting wagons, etc., has been in use for about 12 years and has been eminently successful, it being found by experience that a paint applied by dipping proves equally durable to that formerly applied by means of brushes. Indeed, the durability is increased for the reason, which has been pointed out elsewhere, that the paint finds it way into open joints and crevices which could not be reached by a brush. In some cases a wagon is dipped bodily, while in others it is dismantled and the different parts are dipped separately; again, the smaller portions are placed in an open wire basket which is plunged into the paint. The building in which this painting is done is of considerable extent and a large paint tank is located at each end. A wagon on being completed, or in the case of an old wagon, after having been prepared, is brought to the first tank and is raised from the ground and lowered into the paint, where it remains for about half a minute. It is then immediately raised, allowed to drain over a tank for a few minutes, and then over an inclined floor for a further period. At the end of about half an hour a workman inspects the wagon or other article and removes any tears or runs which may have occurred. The paint being specially prepared this is not usually an arduous undertaking.

The illustrations show very clearly a coach body in process of dipping. Overhead rails run throughout the length of the building and upon these are suspended the painted wagons, which are gradually moved along with a very little exertion, such rails being slightly inclined to facilitate this. By the time the series of wagons reach the further end of the building they are ready to receive a second coat of paint, by being dipped in the second tank. This being done they are then moved back, being at once suspended on the rails until quite dry, when they are hoisted to the upper part of the building, where they are left suspended until they are required for use. The paint is, of course, a special one which is supplied in paste form having the necessary binding ingredients. The colour used is khaki, which is very durable, being composed of earth colours. The thinning is done on the premises and white spirit is employed for the purpose, not turpentine, which would be far too expensive. Formerly benzine was employed, but this necessitated the use of a fan to take away the fumes which came from the spirit. Such a fan is not now found to be necessary.

The tanks are fitted with iron covers bearing upon thick felt and are operated by means of levers placed at a distance, so that should a fire occur they can be closed at a moment's notice. The hoist is worked from the ground by electricity. Formerly the operator of the hoist was located in a cab near the roof, but it was felt that this would be a dangerous position in case of fire, and he now, as stated, does the work from the ground. The work done at Woolwich gives an excellent example of the actual saving which may be effected by using the paint dipping process. Before the painting plant was put in no fewer than 200 painters were constantly employed; now about 40 are fully able to turn out the same or even a larger number of wagons in a given time.

James Gibbons.

Most of the metal sheets as well as finished metal work of various kinds made at these extensive works at Wolverhampton are finished by dipping into special enamels or japans made by Messrs. Mander Bros. The dipping is done by hand and the pieces are placed at the side of the tank to drain. In some cases it is found necessary to go over the work slightly with a brush to remove tears, but such work takes only a few minutes and is used mostly as a precautionary measure.

One coat is usually found sufficient, and at the proper time the iron sheet or metal article is stoved at 250° F. to 300° F. for two hours. Many other articles are also dipped successfully.

Harrison, McGregor & Co.

In the extensive factories of this firm at Leigh, Lancashire, dipping by immersion has been successfully carried on for some years past. Various agricultural implements are dipped bodily in a tank of paint which is fitted with a worm agitator, and is of simple construction. The iron parts are dipped separately, being supported on suitable hangers, while the very small parts are placed in wire baskets for immersion.

Phillips and Son.

The paint dipping plant at these works, which are situated at Sherbourne Street, Birmingham, has been in successful operation for some years past and is applied principally to bedsteads.

The tank holding black japan measures about 5 feet by 18 inches and is some 9 feet deep. The bedstead head and foot are separately dipped by hand into the tank which contains black japan, and are immediately hung on a hook attached to a slowly travelling chain. This chain runs around a rectangular space, and beneath is a metal lined dripping floor. The stove is located diagonally from the tank, so that by the time the bedstead parts reach it the dripping has ceased and they are ready to be baked. The stoving is done at 320° F., and is continued all night. One coat is found to be ample.

A very ingenious arrangement is in use for the application of coloured enamels. Three shallow tanks are mounted on rollers running in angle irons one above the other in such a manner that any one tank may be pulled out when required for use free from the others.

As a rule three coats are given for white work and two for green, blue and most other colours. No white lead is used, but only non-poisonous colours. The stoving is done mostly overnight at a temperature of 250° F. A little rubbing down between coats is done with very fine glass or emery paper. The japans are made by Messrs. Thornley & Knight.

In these works safes are painted, but the work is all done by hand.

The Ford Motor Company.

The extensive works of this company, at Trafford Park, Manchester, contain as complete a plant for painting, japanning, enamelling and varnishing, as it has been the pleasure of the author to inspect.

With characteristic thoroughness every detail which will ensure a first class finish with a minimum of time and labour has been thought out and applied. The result is that not only is every part dealt with most expeditiously but one coat of paint is applied to the whole outer surface of a motor body in the almost incredibly short time of two minutes. Further details will be found in this book under the heads of "Flowing-on," "Motor Parts," and "Iron Rods."

Marshall, Sons & Co., Ltd.

This well-known firm of agricultural implement manufacturers have a large dipping plant at their Gainsborough works, which they employ for painting various agricultural machines made principally of red wood. Some idea of the extent to which this process is applied may be obtained when it is said that on an average nearly 5,000 pieces pass through the dipping plant every month. The process is particularly well adapted for threshing machines and for appliances of the kind which consist of thousands of holes bored in the wood. If the painting were done by hand it would take many hours to paint such a machine, while by dipping it is done even more effectually in a few minutes. The priming coat only is dipped after knots, etc., have been treated with shellac. The tank measures 21ft. long by 7ft. deep and 2ft. 3in. in width. An agitating apparatus is used and the lifting is done by pneumatic appliances.

Hayward Brothers and Eckstein, Limited.

The paint dipping plant in use at the works of this firm, at Union Street, Borough, S.E., is of a comparatively simple type, and consists of a shallow tank in which various cast iron and steel goods are dipped in horizontal position. As a rule, one coat of paint is given, but in certain cases two are required. The bottom of the tank is slanted, and the contents are stirred up from time to time, but no agitating apparatus is used. The principal goods painted by dipping are the frames of Hayward's lights, which are of cast iron and are dipped on one side only, the other side, after the glass is fitted, being done by hand. Metal casements are also dipped in considerable numbers, as well as treads and rises of circular staircases, straight staircases, balconies, etc. These, being made of ornamental open ironwork, contain a large number of small shaped holes, and the dipping process is found to be by far the most effective.

Another speciality of this firm are Hayward's patent steel collapsible gates. The first coat of paint is applied by dipping; this paint, being black, dries flat, i.e., without gloss.

The Crittall Manufacturing Co., Ltd.

These works are at Braintree, Essex, where a large amount of structural steelwork is produced, the chief manufactures being metal windows of all kinds, from the well-known steel casement and sash to metal windows for use in industrial dwellings and specially designed windows for various climates, steel fireproof doors, skylights, steel office and works partitions, shop fronts; frictionless ball race runners for sliding doors, etc.

Fig. 30.—Wagon Store Room, Woolwich Arsenal.

Fig. 31.—Dipping Casements at the Crittall Manufacturing Co.'s Factory, Braintree.

Perhaps the most noticeable feature of these works as far as our subject is concerned, is the very complete system of overhead rails, by means of which the various metal goods produced in the different finishing shops are conveyed to one or other of the paint tanks and then, having been left to dry, are taken to store rooms ready for instant shipment. These rails facilitate handling of the various goods, and reduce the actual expenditure under this particular item to a minimum. The rails are L-shaped, the hanger used for each article or series of articles being of a simple character, consisting of two wheels bearing on the top of the upright flange, while rods secured by bolts pass through the horizontal flange and hold it in position.

We will first describe the tank used for dipping metal windows. This is 15ft. long by 12ft. deep and only 1ft. 6in. wide. Attached to the tank is a large dripping floor measuring some 15ft. by 21ft. covered with sheet iron and inclined toward the tank, so that the paint which drips on to it finds its way back into the tank through a grating provided for the purpose to take off any dried particles. The paint used in this work is made by Messrs. Docker Brothers, and weighs 13 lbs. to the gallon; one coat is found sufficient for the purpose. The sashes or casements being brought in from the finishing room on the overhead rail, they are lowered into the tank by means of a special lowering apparatus designed on the premises. Some idea of this may be had from Fig. 31. In order to keep the load steady during the time it is being dipped, a slight depression or dip in the rail is made immediately over the tank. The sashes are only left in the paint for a few seconds, and are then raised, allowed to drip over the tank for perhaps a minute or two, and then allowed to drip over the adjacent floor for perhaps a quarter of an hour or less. They are then taken farther along and the paint dries in about three hours. Sometimes two, four, six, or even eight casements may be dipped at the same time. Attached to the elevating and lowering apparatus are hooks which pass through one corner of the casements. This causes the parts to hang at an angle which facilitates running off of the paint.

We come now to the department in which the baking or stoving enamel is used as applied to metal furniture in general, as mentioned. In this case the articles are dipped in a manner very similar to that already described, excepting that a large hook, similar in shape to that shown in Fig. 32, is used to support the article to be dipped; the wide opening goes inside the box or file and holds it at an angle so that when it is lowered into the paint all parts are covered inside and out. A few minutes are allowed for dripping, and after two or three hours the articles are ready to be stoved. In this case, Messrs. Docker Brothers' standard colour, a very pleasing dark green, is used. The stoving takes three hours at a temperature of 240° F., or higher in some cases. The tank mentioned is, of course, considerably wider than that used for casements. The dripping floor is in this case inclined toward the centre, which in turn is inclined toward the grating just outside the tank itself. If necessary, special thinners are added to bring up the gloss, but, as a rule, this is unnecessary. It is desirable after the article is dipped to go over it once with a small brush to remove any drips or runs which may possibly appear.

Fig. 32.—Hook Used for Suspending Metal Boxes While Dipping.

Another very important point to be attended to is to exclude all dust, and for this purpose the Crittall Manufacturing Co. have erected in this department screens of wire of the finest mesh over windows, so that no air can pass into the room without the dust being screened off.

Excluding Dust.

A matter of very great importance, yet one which is frequently overlooked in painting iron and other goods which are to have a glossy finish, either air dried or stoved, is to exclude dust from the apartment in which the work is done. In many engineering shops the nature of the business gives rise to a considerable amount of dust, and if this is allowed to enter the paint shop it will be fatal to the appearance of the painted work, as many specks will inevitably settle on the work and mar its appearance.

Fig. 33.—Dipping Casements at Braintree. Note the Narrow Tank used for this Class of Work.

A paint shop is best provided with a concrete floor, and this should be frequently cleaned. The workmen should wear clean overalls, frequently renewed, and even so small a matter as keeping the hair, beard, etc., clean and free from dandruff should be attended to. The doors are best if double, and thick felt may be used with advantage in the joints so as to practically seal the opening when the doors are closed. Air which is admitted, either through ventilators or windows, should be strained before entering the building, and for this purpose silk gauze of the finest mesh is usually employed. In some cases, cotton wool in addition is placed in such a position that the air must pass through it before entering the room. If these precautions are taken it will be found that the quality of the work is greatly enhanced.

It may be observed in this connection that it is important also to provide means of adequate ventilation of the apartment. Moisture charged air has a bad effect upon paint work. Extreme heat is unnecessary, but it is very important that the temperature be maintained at a uniform rate, say 60° F. If the room in which the painting is done is very hot, the paint will be affected and be likely to become too thin for its purpose; while, on the other hand, if the room or articles to be painted are very cold, the paint or enamel will have a tendency to congeal. Both of these defects can be remedied, as already stated, by a good system of ventilation and maintaining the heat, night and day, at a uniform temperature.

A Model Drying Room.

The immense importance of providing a uniform temperature and ensuring an adequate system of ventilation in the room in which goods are placed for air drying can hardly be exaggerated. Unless such a system is in use the actual drying may be greatly retarded and the work stand a chance of being spoiled.

In connection with some of the plant inspected by the author it must be admitted that the provision made in this respect falls far short of what is needed. In one case the work of rubbing down was proceeding in the same shop, although in a different part, in which various goods which had been dipped were hanging up to dry. It need hardly be said that under such conditions it was impossible to keep the work free from specks.

In other cases the drying rooms were inadequate because of the inefficiency of doors and windows. These, it may be remarked,should always be double so as to maintain the heat uniformly.

Every varnish user knows that a draught of cold air which is allowed to reach a coat of varnish while drying is fatal alike to its appearance and durability. The result is almost certain to be a case of "blooming," which to the uninitiated may be described as a film not unlike the bloom of a freshly coloured plum which comes on the surface of varnish exposed under such conditions. Those unacquainted with varnish vagaries are apt to regard this trouble as being the result of inferior materials used in its manufacture. As a matter of fact it indicates nothing of the kind because, speaking generally, the higher grades of varnishes are the most susceptible.

Without doubt the best and by far the most economical plan to adopt is to have a drying room specially built for the purpose of receiving the articles to be dried. If constructed on scientific principles this will not only give a uniform temperature entirely free from draughts and dust but will considerably expedite the work, thereby allowing of a quicker delivery of goods and effecting a great saving of valuable floor space.

The author inspected such a drying room at the works of Messrs. Pinchin, Johnson, and Co., Ltd., at Silvertown, and a description of it will doubtless prove of interest. It is built of 5-ply wood and is about 16 feet square, sufficiently large to hold two full-sized motor bodies or several dozen perambulators, hand wagons, etc. The actual size may, of course, be varied according to the size of and number of articles to be dried. Air is admitted through two ducts situated close to the floor through fine wire gauze, which is provided with a lifting cover by which the amount of air admitted may be regulated.

Immediately over the two air ducts mentioned is a coil of steam pipes which heats the air to, say, 110° F. This, of course, causes it to rise toward the ceiling, but the angle between the ceiling and wall is rounded off by a cove, so that the current of heated air is directed along the ceiling toward the centre of the room where there is another cove and beneath it a coil of cold air pipes which lowers the temperature somewhat. Thus is created a constant motion of the air which may be regarded as the essence of the system.

But there is another very important provision in the shape of an automatic control. This cuts off the steam when any desired heat is attained so that when the drying room is filled up at night before the works close it can safely be left until the morning when the drop in temperature will not be more than 2 degrees. The steam may be admitted at, say, 10 lbs. pressure, but as soon as the room is heated from 2 to 2½ lbs. will be found to be sufficient. The actual time for heating the room to 120° F. is from 15 to 20 minutes.

The speed with which work is turned out by this well-considered adjunct may be gauged from the fact that a panel may receive one coat of enamel and two coats of flatting varnish in one day, or four coats of japan in the same period.

In addition to the advantages mentioned is the most important one that the drying room renders the manufacturer who is fortunate enough to possess one quite independent of the weather. In the words of the inventors and patentees, "one enabled by its use to create one's own climate."

Fig. 34.—Design for Show Card done by Spraying.

CHAPTER IV.