(d) Immerse each mildewed sheet separately in a solution made in the proportions of ½ lb. lime chloride to 1 pint water. Let it stand, with frequent stirring, for 24 hours, and then strain through muslin, and finally add 1 qt. water. Mildew and other stains will be found to disappear very quickly, and the sheets must then be passed separately through clear water, or the lime chloride, if left in the paper, will cause it to rot. Old prints, engravings, and every description of printed matter may be successfully treated in the same manner.
(e) “I have in my time cleaned many hundreds. The plan which I adopt is as follows:—I place them, one or two at a time, in a shallow dish, and pour water over them until they are completely soaked or saturated with it. I then carefully pour off the water, and pour on to the prints a solution of lime chloride (1 part liquor calcis chloratæ, to 39 of water). As a general rule, the stains disappear as if by magic, but occasionally they are obstinate. When that is the case, I pour on the spot pure liquor calcis chloratæ, and if that does not succeed, I add a little dilute nitro-muriatic acid. I have never had a print which has not succumbed to this treatment—in fact, as a rule they become too white. As soon as they are clean they must be carefully washed with successive portions of water until the whole of the chlorine is got rid of. They should then be placed in a very weak solution of isinglass or glue, and many collectors colour this solution with coffee-grounds, &c., to give a yellow tint to the print. They should be dried between folds of blotting-paper, either in a press or under a heavy book, and finally ironed with an ordinary flat-iron to restore the gloss; placing clean paper between the iron and the print. Grease stains are much more difficult. I find benzine best. Small grease spots may be removed by powdered French chalk being placed over them, a piece of clean blotting-paper over the chalk, and a hot iron over that.” (F. Andrews.)
(f) Mildew often arises from the paste used to attach the print. Take a solution of alum of medium strength and brush on back and face of the engraving 2 or 3 coats, then make the frame air-tight by pasting a strip of paper all round the inside of glass, leaving about ½ in. overlapping (taking care not to paste the paper on the glass, so as to be seen from the front), then place your glass in frame, take the overlapping piece and paste to side of rebate; place your picture in position, spring backboard in, and then place a sheet of strong paper (brown) on the table, damp it, and paste round back of frame, lay it on to the paper, leave to dry, cut level. If this does not answer there will be no help for it, but dust off as the mould accumulates. Do not brush on surface with the alum if the engraving is coloured, but several coats on the back.
(g) A plan recommended by Wm. Brooks is to get a dish or china tray a little larger than the engraving to be operated upon; if, smaller, there is a great risk of tearing and damaging the engraving. The bleaching agent used is Holmes’ ozone bleach. The strength preferred is 1 part bleach to 10 of water, well shaken up before pouring into the dish. A much stronger solution can be used (say 1 in 5), but the weaker it is the easier is its removal from the paper afterwards. The engraving is immersed in the solution face upwards, avoiding bubbles. The only caution to be observed is that the sodden engraving is somewhat rotten, and needs careful handling. If the engraving be only slightly stained, ½ hour will suffice to clean it, but if quite brown it may require 4 hours. After all the stains are removed, and the paper has regained its whiteness, pour the solution back into the bottle, as it can be re-used till it becomes discoloured; fill up the dish with water, changing frequently for about 3 hours, or place it in running water. When the engraving is sufficiently washed, it can be taken out, blotted off, and hung up to dry. When quite dry, it may be ironed on the back with a warm flat-iron, which must not be too hot. (Brit. Jl. Photog.)
(h) If the engravings are very dirty, take 2 parts salt and 1 soda, and pound them together until very fine. Lay the engraving on a board, and fasten it with drawing-pins, and then spread the mixture dry equally over the surface to be cleaned. Moisten the whole with warm water and a little lemon-juice, and, after it has remained about a minute, or even less, tilt the board up on its end, and pour over it a kettleful of boiling water, being careful to remove all the mixture, and avoid rubbing. If the engraving is not very dirty, the less soda used the better, as it has a tendency to give a yellow hue.
(i) Does not injure the quality or texture of the engraving. Immerse the print in a lye made by adding to the strongest muriatic acid its own weight of water; to 3 parts of this mixture add 1 of red oxide of lead or black oxide of manganese. If the print is very dirty, it may remain in the liquid 24 hours without harm. Indian ink stains should be first assisted out with hot water, and pencil marks with rubber or breadcrumbs. If there be old paste on the back, it must be removed with warm water. The saline crystals left after immersion are removed by several rinsings in warm water.
(j) To remove surface dirt from engravings and mezzotints, the most effectual plan is to use common bookbinders’ paste, applied with a paste brush, both to front and back of the print; the paste will take up the whole of the dirt, which will come away with the paste when it is removed with water. A bath of plain water completes the operation, from which the print will emerge as fresh as when first issued. Many a guinea has been earned by this simple but efficacious plan.
Frames.—(a) Fly-marks can be cleaned off with soap and water used sparingly on end of finger covered by piece of rag. When all cleared off, rinse with cold water, and dry with chamois leather; next buy 1 lb. (1d.) of common size, and 2 penny paint pans. Boil a little of the size in one of the pans with as much water as will just cover it. When boiled, strain through muslin into clean pan, and apply thinly to frames with camel-hair brush (called technically a “dabber,” and costing 6d. to 1s. each). Take care you do not give the frames too much water and “elbow grease.” On no account use gold size, as it is used only in regilding, and if put on over the gold would make it dull and sticky.
(b) Dissolve a very small quantity of salts of tartar in a wine bottle of water, and with a piece of cotton wool soaked in the liquid dab the frames very gently (no rubbing on any account, or you will take off the gilt), then stand up the frames so that water will drain away from them conveniently, and syringe them with clean water. Care must be taken that the solution is not too strong.
(c) If new gold frames are varnished with the best copal varnish, it improves their appearance considerably, and fly-marks can then be washed off carefully with a sponge. The frames also last many times longer. It also improves old frames to varnish them with it.