which are exposed to weather it is much better to use thick white-lead paint in place of glue. A damp-resisting glue may be made by soaking in water enough glue to make a pint when dissolved ready for use, and, after dissolving it as usual, but in as little water as possible, adding three tablespoonfuls of boiled linseed oil, keeping up the heat and constantly stirring the glue until the oil disappears, then adding and thoroughly incorporating a tablespoonful of whiting. Glue to which bichromate of potash has been added is, after exposure to strong light, rendered insoluble; and glue compounded with skim milk instead of water resists damp better than ordinary glue, but a joint made with it will not stand for long in a wet situation. There are ready-made waterproof glues on the market. One kind is sold in cone-shaped tins which have spring bottoms like those of small oilcans. The hole in the top of the cone, the exit for the glue, is stopped with a pin, whose head is soldered to the tin with soft composition, which can be easily removed with a knife, to allow of the withdrawal of the pin, which must be replaced as soon as sufficient glue has been pressed out of the tin. Thus the glue can be applied without heating and without using a brush. After the glue is set, it will bear prolonged exposure to damp, or actual immersion in water for a long period. It is economical, because it can be used without the slightest waste.
Fig. 494.—Cane Brush for Glue.
