| Borax | 30 grains |
| Shellac | 60 grains |
| Glycerine | 30 minims |
| Water | 2 ounces |
Boil till dissolved, filter, and add aniline black, 120 grains.
Label: Apply the solution with a brush, and repeat when dry if necessary.
Ordinary Negative Varnish.—
| Gum sandarac | 1 ounce |
| Orange shellac | 1/2 ounce |
| Castor oil | 90 minims |
| Methyl alcohol | 1 pint |
Allow to stand with occasional agitation till dissolved, and then filter. Label: The negative should be heated before a fire till it can be comfortably borne on the back of the hand, and then the varnish flowed over, any excess being drained off, and the negative should then be again placed near the fire to dry.
Water Varnish.
The use of water varnish, however, does away with the necessity of employing collodion as an additional protection to a negative, and is, perhaps, the best known remedy against damage from silver staining that experienced workers are acquainted with. As a varnish it is not costly, neither is it difficult to make in reasonably small quantities, while its application is simplicity itself. The following formula is an excellent sample of water varnish:
Place in a clean, enameled pan 1 pint of water, into which insert 4 ounces of shellac in thin flakes, and place the vessel on a fire or gas stove until the water is raised to 212° F. When this temperature is reached a few drops of hot, saturated solution of borax is dropped into the boiling pan containing the shellac and water, taking care to stir vigorously with a long strip of glass until the shellac is all dissolved. Too much borax should not be added, only just sufficient to cause the shellac to dissolve, and it is better to stop short, if anything, before all the flakes dissolve out than to add too much borax. The solution is then filtered carefully and, when cold, the water varnish is ready for use.