ENGRAVINGS: THEIR PRESERVATION
(See also Pictures, Prints, and Lithographs.)
Cleaning Of Copperplate Engravings.
Restoration Of Old Prints.
Surprising results are obtained from the use of hydrogen peroxide in the restoration of old copper or steel engravings or lithographs which have become soiled or yellow, and this without the least injury to the picture. The cellulose which makes the substance of the paper resists the action of ozone, and the black carbon color of these prints is indestructible.
To remove grease or other spots of dirt before bleaching, the engravings are treated with benzine. This is done by laying each one out flat in a shallow vessel and pouring the benzine over it. As benzine evaporates very rapidly, the vessel must be kept well covered, and since its vapors are also exceedingly inflammable, no fire or smoking should be allowed in the room. The picture is left for several hours, then lifted out and dried in the air, and finally brushed several times with a soft brush. The dust which was kept upon the paper by the grease now lies more loosely upon it and can easily be removed by brushing.
In many cases the above treatment is sufficient to improve the appearance of the picture. In the case of very old or badly soiled engravings, it is followed by a second, consisting in the immersion of the picture in a solution of sodium carbonate or a very dilute solution of caustic soda, it being left as before for several hours. After the liquid has been poured off, the picture must be repeatedly rinsed in clear water, to remove any remnant of the soda.
By these means the paper is so far cleansed that only spots of mold or other discolorations remain. These may be removed by hydrogen peroxide, in a fairly strong solution. The commercial peroxide may be diluted with 2 parts water.
The picture is laid in a shallow vessel, the peroxide poured over it, and the vessel placed in a strong light. Very soon the discolorations will pale.
To Reduce Engravings.
ENLARGEMENTS: See Photography.
ENVELOPE GUM: See Adhesives, under Mucilages.
EPIZOOTY: See Veterinary Formulas.