Shellac.—A good shellac mountant is made by mixing 4 parts of shellac with I part of mastic, powdered, and dissolving in from io to 15 parts of spirit of wine. It must be put in a warm place, and after a few days the gums will be dissolved. If too thick, add more alcohol. The print must be quite dry, and the back brushed over with the mountant, imme diately placed on the mount, and allowed to dry. A thin print can be thus mounted without cockling.
Starch.—Rub up I part of good white starch with 2 or 3 parts of cold water into a per fectly smooth cream-like paste, and then with constant stirring pour this into from 6 to 8 parts of boiling water and continue the heat for five minutes, stirring constantly. Allow to cool, and if not free from lumps squeeze it through muslin. Another plan is to rub the starch into a paste, as above, and to pour boiling water upon it, stirring constantly until it jellifies. All starch mountants should be allowed to cool and the top skin be taken off before use. Such pastes keep good for two or three days only, but the addition of a few drops of oil of cloves or carbolic acid will preserve them for a longer period.
Starch and Gelatine.—This is a stiff, smooth paste which does not cause cockling when properly applied. Take 2 parts of wheat starch and 1 part of rice starch, and mix thoroughly. Soak 6o grs. of gelatine in to oz. of water and heat till dissolved. When the latter has cooled to about 7o° P. (21° C.), add the mixed starches in small quantities, stirring all the time until the mixture is of the consistency of thin cream. Heat slowly, in a jar placed
in a saucepan of water, until the starch thickens ; and continue the heat until about one-fifth of the water has evaporated. Then add slowly, with constant stirring, 1 oz. of alcohol and about 45 drops of oil of cloves.
Starch and Gum.—A suitable formula is :— Gum arabic . 1 oz. ioo g.
Rice starch . . 1 3) ioo „ White sugar • 4 )3 ,. » Waterq.s. q.s.
Dissolve the gum in as small a quantity of water as possible, add the sugar, stir in the starch, which nas been rubbed up into a cream with water, and boil the mixture until the starch is jellified.
Adhesive Prints and Mounts.—Adhesive mounts are made by spreading a thick solution of gum tragacanth upon them and allowing to dry. When the damp print is pressed into contact with the gummed surface, there is immediate adhesion. Similarly, glazed prints, while still on the glass or ferrotype plate, may be coated with : A. Bleached shellac . 2 OZ. 200 g.
Alcohol 4 )) 40o ccs.
B. Borax . . 24 grs. 5 g.
Curd soap powder 24 „ 5 Water . . Ioo mires. 20 CCS.
Allow A to stand for a week and agitate frequently ; then add B, thoroughly shake, and use the clear part, or filter. After the prints have been coated and allowed to dry, they are stripped from the support, pressed into contact with the mount, and attached by passing a hot iron over them, interposing a piece of blotting paper between iron and print.