BRASS
Formulas for the making of Brass will be found under Alloys.
Colors For Polished Brass.
| Sulphate of copper | 120 grains |
| Hydrochlorate of ammonia | 30 grains |
| Water | 1 quart |
greenish shades are obtained. With the following solution all the shades of brown from orange brown to cinnamon are obtained: {128}
| Chlorate of potash | 150 grains |
| Sulphate of copper | 150 grains |
| Water | 1 quart |
The following solution gives the brass first a rosy tint and then colors it violet and blue:
| Sulphate of copper | 435 grains |
| Hyposulphite of soda | 300 grains |
| Cream of tartar | 150 grains |
| Water | 1 pint |
| Upon adding to the last solution | |
| Ammoniacal sulphate of iron | 300 grains |
| Hyposulphite of soda | 300 grains |
there are obtained, according to the duration of the immersion, yellowish, orange, rosy, then bluish shades. Upon polarizing the ebullition the blue tint gives way to yellow, and finally to a pretty gray. Silver, under the same circumstances, becomes very beautifully colored. After a long ebullition in the following solution we obtain a yellow-brown shade, and then a remarkable fire red:
| Chlorate of potash | 75 grains |
| Carbonate of nickel | 30 grains |
| Salt of nickel | 75 grains |
| Water | 16 ounces |
The following solution gives a beautiful, dark-brown color:
| Chlorate of potash | 75 grains |
| Salt of nickel | 150 grains |
| Water | 10 ounces |
The following gives, in the first place, a red, which passes to blue, then to pale lilac, and finally to white:
| Orpiment | 75 grains |
| Crystallized sal sodæ | 150 grains |
| Water | 10 ounces |
The following gives a yellow brown:
| Salt of nickel | 75 grains |
| Sulphate of copper | 75 grains |
| Chlorate of potash | 75 grains |
| Water | 10 ounces |
On mixing the following solutions, sulphur separates and the brass becomes covered with iridescent crystallizations:
| I.— | Cream of tartar | 75 grains |
|---|---|---|
| Sulphate of copper | 75 grains | |
| Water | 10 ounces | |
| II.— | Hyposulphite of soda | 225 grains |
| Water | 5 ounces |
Upon leaving the brass objects immersed in the following mixture contained in corked vessels they at length acquire a very beautiful blue color:
| Hepar of sulphur | 15 grains |
| Ammonia | 75 grains |
| Water | 4 ounces |
Miscellaneous Coloring Of Brass.
A verdigris color on brass is produced by treating the articles with dilute acids, acetic acid, or sulphuric acid, and drying.
Brown in all varieties of shades is obtained by immersing the metal in solutions of nitrates or ferric chloride after it has been corroded with dilute nitric acid, cleaned with sand and water, and dried. The strength of the solutions governs the deepness of the resulting color.
Violet is caused by immersing the thoroughly cleaned objects in a solution of ammonium chloride.
Chocolate color results if red ferric oxide is strewn on and burned off, followed by polishing with a small quantity of galena.
Olive green is produced by blackening the surface with a solution of iron in hydrochloric acid, polishing with galena, and coating hot with a lacquer composed of 1 part varnish, 4 parts cincuma, and 1 part gamboge.
A steel-blue coloring is obtained by means of a dilute boiling solution of chloride of arsenic, and a blue one by a treatment with strong hyposulphite of soda. Another formula for bluing brass is: Dissolve 10 parts of antimony chloride in 200 parts of water, and add 30 parts of pure hydrochloric acid. Dip the article until it is well blued, then wash and dry in sawdust.
Black is much used for optical brass articles and is produced by coating with a solution of platinum or auric chloride mixed with nitrate of tin.
Coloring Unpolished Brass.
Coloring Fluid For Brass.
Dissolve the salt in water and dip the metal in the solution obtained. The intensity of the color will be proportional to the time of immersion. After removing the object from the liquid, rinse with water and dry in sawdust.
Black Color On Brass.
The brass which it is desired to blacken is first boiled in a strong potash solution to remove grease and oil, then well rinsed and dipped in the copper solution, which has previously been heated to from 150° to 175° F. This solution, if heated too hot, gives off all the ammonia. The brass is left in the solution until the required tint is produced. The color produced is uniform, black, and tenacious. The brass is rinsed and dried in sawdust. A great variety of effects may be produced by first finishing the brass before blackening, as the oxidizing process does not injure the texture of the metal. A satisfactory finish is produced by first rendering the surface of the brass matt, either by scratch-brush or similar methods, as the black finish thus produced by the copper solution is dead—one of the most pleasing effects of an oxidized surface. Various effects may also be produced by coloring the entire article and then buffing the exposed portions.
The best results in the use of this solution are obtained by the use of the so-called red metals—i. e., those in which the copper predominates. The reason for this is obvious. Ordinary sheet brass consists of about 2 parts of copper and 1 part of zinc, so that the large quantity of the latter somewhat hinders the production of a deep-black surface. Yellow brass is colored black by the solution, but it is well to use some metal having a reddish tint, indicating the presence of a large amount of copper. The varieties of sheet brass known as gilding or bronze work well. Copper also gives excellent results. Where the best results are desired on yellow brass a very light electroplate of copper before the oxidizing works well and gives an excellent black. With the usual articles made of yellow brass this is rarely done, but the oxidation carried out directly.
Black Finish For Brass.
II.—The blacking of brass may be accomplished by immersing it in the following solution and then heating over a Bunsen burner or a spirit flame: Add a saturated solution of ammonium carbonate to a saturated copper-sulphate solution, until the precipitate resulting in the beginning has almost entirely dissolved. The immersion and heating are repeated until the brass turns dark; then it is brushed and dipped in negative varnish or dull varnish. {130}
To Give A Brown Color To Brass.
II.—A very handsome brown may be produced on brass castings by immersing the thoroughly cleaned and dried articles in a warm solution of 15 parts of sodium hydrate and 5 parts of cupric carbonate in 100 parts of water. The metal turns dark yellow, light brown, and finally dark brown, with a greenish shimmer, and, when the desired shade is reached, is taken out of the bath, rinsed, and dried.
III.—Paint the cleaned and dried surface uniformly with a dilute solution of ammonium sulphide. When this coating is dry, it is rubbed over, and then painted with a dilute ammoniacal solution of arsenic sulphide, until the required depth of color is attained. If the results are not satisfactory the painting can be repeated after washing over with ammonia. Prolonged immersion in the second solution produces a grayish-green film, which looks well, and acquires luster when polished with a cloth.
Refinishing Gas Fixtures.
If the bronze paint is made up with ordinary varnish it is liable to become discolored from acid which may be present in the varnish. One method proposed for obviating this is to mix the varnish with about five times its volume of spirit of turpentine, add to the mixture dried slaked lime in the proportion of about 40 grains to the pint, agitate well, repeating the agitation several times, and finally allowing the suspended matter to settle and decanting the clear liquid. The object of this is to neutralize any acid which may be present. To determine how effectively this has been done the varnish may be chemically tested.
Steel Blue And Old Silver On Brass.
Tombac Color On Brass.
Graining Of Brass.
| Silver powder | 28 | 28 | 28 parts |
| Tartar | 283 | 110–140 | 85 parts |
| Cooking salt | 900 | 370 | 900 parts |
This powder is moistened with water and applied to the object. Place the article with the cork support in a flat dish and rub on the paste with a stiff brush while turning the dish incessantly. Gradually fresh portions of graining powder are put on until the desired grain is obtained. These turn out the rounder the more the dish and brush are turned. When the right grain is attained, rinse off with water, and treat the object with a scratch brush, with employment of a decoction of saponaria. The brushes must be moved around in a circle in brushing with the pumice stone, as well as in rubbing on the graining powder and in using the scratch brush. The required silver powder is produced by precipitating a diluted solution of silver nitrate with some strips of sheet copper. The precipitated silver powder is washed out on a paper filter and dried at moderate heat.
The Dead, Or Matt, Dip For Brass.
The dead dip is a mixture of oil of vitriol (sulphuric acid) and aqua fortis (nitric acid) in which there is enough sulphate of zinc (white vitriol) to saturate the solution. It is in the presence of the sulphate of zinc that the essential difference between the bright and the dead dip exists. Without it the dead or matt surface cannot be obtained.
The method generally practiced is to add the sulphate of zinc to the mixed acids (sulphuric and nitric), so that some remains undissolved in the bottom of the vessel. It is found that the sulphate of zinc occurs in small crystals having the appearance of very coarse granulated sugar. These crystals readily settle to the bottom of the vessel and do not do the work of matting properly. If they are finely pulverized the dip is slightly improved, but it is impossible to pulverize such material to a fineness that will do the desired work. The use of sulphate of zinc, then, leaves much to be desired.
The most modern method of making up the dead dip is to produce the sulphate of zinc directly in the solution and in the precipitated form. It is well known that the most finely divided materials are those which are produced by precipitation, and in the dead dip it is very important that the sulphate of zinc shall be finely divided so that it will not immediately settle to the bottom. Therefore it should be precipitated so that when it is mixed with the acids it will not settle immediately. The method of making the sulphate of zinc directly in the solution is as follows:
Take 1 gallon of yellow aqua fortis (38° F.) and place in a stone crock which is surrounded with cold water. The cold water is to keep the heat, formed by the reaction, from evaporating the acid. Add metallic zinc in small pieces until the acid will dissolve no more. The zinc may be in any convenient form—sheet clippings, lumps, granulated, etc., that may be added little by little. If all is added at once it will boil over. When the acid will dissolve no more zinc it will be found that some of the acid has evaporated by the heat, and it will be necessary to add enough fresh acid to make up to the original gallon. When this is done add 1 gallon of strong oil of vitriol. The mixture should be stirred with a wooden paddle while the oil of vitriol is being added.
As the sulphuric acid is being added the solution begins to grow milky, and finally the whole has the consistency of thick cream. This is caused by the sulphuric acid (oil of vitriol) precipitating out the sulphate of zinc. Thus the very finely divided precipitate of sulphate of zinc is formed. If one desires to use known quantities of acid and zinc the following amounts may be taken: Oil of vitriol, 1 gallon; aqua fortis (38° F.), 1 gallon; metallic zinc, 6 ounces.
In dissolving the zinc in the aqua fortis it is necessary to be sure that none remains undissolved in the bottom.
The dead or matt dip is used hot, and, therefore, is kept in a stone crock surrounded with hot water. The articles to be matted are polished and cleaned, and the dip thoroughly stirred with a wooden paddle, so as to bring up the sulphate of zinc which has settled. Dip the work in the solution and allow it to remain until the matt is obtained. This is a point which can be learned only by experience. When the brass article is first introduced there is a rapid action on the surface, but in a few seconds this slows down. Remove the article and rinse and immediately dip into the usual bright dip. This {132} is necessary for the reason that the dead dip produces a dark coating upon the surface, which, were it left on, would not show the real effect or the color of the metal. The bright dip, however, removes this and exposes the true dead surface.
The usual rule for making up the dead dip is to use equal parts of oil of vitriol and aqua fortis; but these may be altered to suit the case. More oil of vitriol gives a finer matt, while a larger quantity of aqua fortis will give a coarser matt. When the dip becomes old it is unnecessary to add more zinc, as a little goes into the solution each time anything is dipped. After a while, however, the solution becomes loaded with copper salts, and should be thrown away.
A new dip does not work well, and will not give good results when used at once. It is usual to allow it to remain over night, when it will be found to be in a better working condition in the morning. A new dip will frequently refuse to work, and the addition of a little water will often start it. The water must be used sparingly, however, and only when necessary. Water, as a usual thing, spoils a dead dip, and must be avoided. After a while it may be necessary to add a little more aqua fortis, and this may be introduced as desired. Much care is needed in working the dead dip, and it requires constant watching and experience. The chief difficulty in working the dead dip is to match a given article. The only way that it can be done is to “cut and try,” and add aqua fortis or oil of vitriol as the case requires.
The dead or matt dip can be obtained only upon brass or German silver; in other words, only on alloys which contain zinc. The best results are obtained upon yellow brass high in zinc.
To Improve Deadened Brass Parts.
Pickle For Brass.
Pickling Brass To Look Like Gold.
Pickle For Dipping Brass.
Restoration Of Brass Articles.
Tempering Brass.
Drawing Temper From Brass.
BRASS, FASTENING PORCELAIN TO: See Adhesives.
BRASS POLISHES: See Polishes.
BRASS SOLDERS: See Solders.
BRASS BRONZING: See Plating.
BRASS CLEANERS: See Cleaning Preparations and Methods.
BRASS PLATINIZING: See Plating.
BRASS, SAND HOLES IN: See Castings.
BRASSING: See Plating.
BREAD, DOG: See Dog Biscuit.