Glycerine and gum arabic make a very good adhesive of a fluid nature suited to mounting photographs; and although glycerine is hygroscopic by itself, such tendency to absorb moisture is checked by the reverse nature of the gum arabic; consequently an ideal fluid mucilage is produced. The proportions of the several ingredients are these:
| Gum arabic, genuine (gum acacia, not Bassora gum) | 4 ounces |
| Boiling water | 12 ounces |
| Glycerine, pure | 1 ounce |
First dissolve the gum in the water, and then stir in the glycerine, and allow all débris from the gum to deposit before using. The following adhesive compound is also one that is free from chemical reactions, and is suited for photographic purposes:
| Water | 2 pints |
| Gum dragon, powdered | 1 ounce |
| Gum arabic, genuine | 4 ounces |
| Glycerine | 4 ounces |
Mix the gum arabic with half the water, and in the remainder of the water dissolve the gum dragon. When both solids are dissolved, mix them together, and then stir in the glycerine.
The following paste will be found a useful mountant:
| Gum arabic, genuine | 1 ounce |
| Rice starch | 1 ounce |
| White sugar | 4 ounces |
| Water, q. s. |
Dissolve the gum in just sufficient water to completely dissolve it, then add the sugar, and when that has completely dissolved stir in the starch paste, and then boil the mixture until the starch is properly cooked.
A very strong, stiff paste for fastening cardboard mounts to frames, wood, and other materials is prepared by making a bowl of starch paste in the usual way, and then adding 1 ounce of Venice turpentine per pound of paste, and {42} boiling and stirring the mixture until the thick turpentine has become well incorporated. Venice turpentine stirred into flour paste and boiled will also be found a very adhesive cement for fastening cardboard, strawboard, leatherette, and skiver leather to wood or metal; but owing to the resinous nature of the Venice turpentine, such pastes are not suitable for mounting photographic prints. The following half-dozen compounds are suitable mountants to use with silver prints:
| Alcohol, absolute | 10 ounces |
| Gelatine, good | 1 ounce |
| Glycerine | 1/2 to 1 ounce |