GLUE.
How to dissolve and how to use.
Glue, which one workman finds all right and from which he obtains excellent results, may, in the hands of another workman, prove a failure from many causes, some of which may be that the glue is too thick, or it may have been chilled before the pieces were clamped together, or the glue is too thin. The workman has to know from experience just how thick the glue has to be for the work he has on hand. A hardwood piece of work requires a thinner glue than soft wood. The average consistency of glue should be about like that of thin syrup, and should be applied hot to the work. Sometimes in cold weather the glue “sets” quickly; then the pieces to be glued should be heated so that the glue may be kept soft. When the pieces are put together clamp them up quickly or rub them together, forcing out the surplus glue from the joint. When work is glued together it should stand from eight to twelve hours before being handled.
When the end grain of wood has to be glued, it should first be sized, that is, it should be given a coat of glue and let dry. This fills the pores of the wood so that when the joint is made it will hold.
There are two kinds of glue, animal and fish glue. Animal glue is made from the refuse of slaughter houses and tanneries, and the number of grades and colors are innumerable. Fish glue is made chiefly from the entrails and skin of fish, and is mostly in liquid form.
To prepare glue, put as much as is needed in the glue pot and cover over with cold water; then let it soak from six to ten hours, according to the quantity; after this place the glue pot in the water kettle or glue heater, and apply heat in any convenient way to the water, which in turn heats the glue. The use of the two vessels is to prevent the glue from burning.
Glue should always be used as freshly as possible, for then it holds better than when it is old.
It can be made to stand the weather by adding boiled linseed oil. Add the linseed oil to the glue slowly, stirring it all the time, the proportion of oil to glue being two ounces of oil to sixteen ounces of glue. Another method of preparing glue to stand the weather, is to use skimmed milk instead of water when preparing it.