Glue, being an animal substance, must be kept sweet. To do this it is necessary to keep it cool after it is once dissolved and not in use. In all cases keep the glue kettle clean and sweet by cleaning it often.

Good glue requires more water than poor, consequently you can not dissolve six pounds of good glue in the same quantity of water that you can six pounds of poor. The best glue will require from one-half to more than double the water that is required with poor glue, which is clear and red, and the quality of which can be discovered by breaking a piece. If good it will break hard and tough, and when broken will be irregular on the broken edge. If poor it will break comparatively easy, leaving a smooth, straight edge.

In dissolving glue it is best to weigh the glue and weigh or measure the water. If not done there is a liability of getting more glue than the water can properly dissolve. It is a good plan, when once the quantity of water that any sample of glue will take up has been ascertained, to put the glue and water together at least six hours before heat is applied, and if it is not soft enough then let it remain longer in soak, for there is no danger to good glue remaining in pure water even for 48 hours.

The advantage of frozen glue is that it can be made up at once, on account of its being so porous. Frozen glue of same grade is as strong as if dried.

If glue is of first-rate quality it can be used on most kinds of wood work very thin, and make the joint as strong as the original. White glue is made white by bleaching.