Others suggest dissolving glue in an equal quantity of water and adding about as much linseed oil as water, with the aid of heat, until a jelly is formed. This mixture is said to be practically waterproof.
A patented process has recently been put out for which the claim is made that it can be applied to any glue irrespective of grade or make, rendering it absolutely waterproof. The result is attained by mixing the glue with certain chemicals in specified proportions, and then adding a certain amount of formaldehyde. Any amount of glue can be treated and the process is said to be most effective.
VEGETABLE GLUE
Of recent years efforts have been made to find a substitute for animal glue. The effort has met with success to a certain extent for particular kinds of work. Probably the newest addition to the list of vegetable glues is the mineral glue-silicate of soda. Liquid silicates were first sold for the manufacture of soap. In recent years certain forms have been used for light adhesive paper work. It is used in places where glue is too slow setting.
QUICK SETTING GLUES
When a glue is desired to set very quickly the manufacturer can usually furnish glue with the setting qualities desired for the particular work in hand. If this cannot be done, for any reason, remember that the temperature of the glue is an important factor. A low temperature aids in quick setting. Some paper box manufacturers have had successful results in quick setting by adding a small quantity of turpentine to the liquid glue. Some add silicate of soda.
FLEXIBLE GLUES
Specially made glues are supplied by manufacturers for work in which flexibility is needed. An easy way to increase the flexible quality of glue is to add a little glycerine to the liquid glue.