The fabrication is quite simple. Cover pure gelatine with water, and after swelling up, pour off the water and dissolve the jelly over a water-bath. After allowing the solution to cool somewhat, add the coloring matter previously dissolved in water.
In place of pure gelatine, a solution of ordinary bone-glue may be used. In order to clarify it add O.14 oz. of oxalic acid dissolved in water to every 5.5 lbs. of glue. To make the foils more flexible add also one-half pint of spirit of wine and O.28 oz. of rock candy or a small quantity of glycerine.
Aniline colors soluble in water are best adapted for coloring the foils; for red, fuchsine, eosine or ponceau, for blue, blue de Parme, for green, aldehyde green, for yellow, picric acid, and for the various shades, mixtures of the above colors.
A durable blue is also produced by indigo solution, yellow, by decoction of saffron, green, by mixing blue and yellow, red, by a solution of carmine in spirit of sal ammoniac, and violet, by mixing blue and carmine.
The gelatine solutions are poured upon ground-glass plates, previously polished with elutriated rouge, and rubbed with Spanish chalk. The foils are so smooth upon the glass side that when dry they can be detached without much difficulty. If both sides are required to be smooth, the foils are dried between two glass plates. In many respects their manufacture resembles that of “Gelatine Veneers.”
Gelatine foils are used for printing sacred images, visiting cards, labels, in the manufacture of fancy articles, artificial flowers, etc.
For the manufacture of artificial flowers very soft and flexible sheets are made by adding ½ part of glycerine to 1 part of gelatine and mixing intimately in dissolving the gelatine.
Such gelatine sheets brushed over in addition with Peruvian balsam can also be advantageously used for tying up wounds instead of gutta-percha cloth which tears easily and rots soon. They form an air-tight bandage which clings closely to the parts of the body, and beside the glycerine contained in them exerts a beneficial cooling effect and acts as an antiseptic.
Gelatine Veneers.
Franchi, as far back as 1814, prepared artificial ivory by mixing gelatine solution with earthy substances. This idea has been again taken up in modern times for the manufacture of veneers imitating not only ivory, but also avanturin, lapis lazuli, malachite, mother-of-pearl, and tortoise shell. These imitations are much liked by manufacturers of fancy articles, workers in leather, cabinet-makers, etc. They are prepared as follows:—