This is a very convenient application for slight wounds or cuts, and is easily made. It is found of various colors, chiefly black and flesh-colored; and this depends altogether upon the color of the silk used, though if only white silk were at hand it would be easy to color it slightly with a little alkanet, or any other vegetable coloring-matter. The following formula gives good results: -
Soak isinglass in a little warm water for 24 hours; then evaporate nearly all the water by gentle heat; dissolve the residue in a little proof spirits of wine (alcohol of 85 per cent), and strain the whole through a piece of open linen. The strained mass should be a stiff jelly when cool. Now stretch a piece of silk or sarsanet on a wooden frame, and fix it tight with tacks or packthread. Melt the jelly, and apply it to the silk thinly and evenly with a badger-hair or any very fine brush. A second coating must be applied when the first has dried, and in some cases even a third is given. "When thoroughly dry, apply over the whole surfaea two or three coatings of balsam of Peru.
Plaster thus made is said to be very pliable, and never breaks. The quality of court-plaster depends upon the quality of the silk used, and also upon the care taken to exclude all irritating and poisonous matter. Many of the dyed silks are absolutely poisonous; and if the isinglass is kept too long in water, so as to become tainted, it may cause serious injury.