Page:Cyclopedia of Painting-Armstrong, George D (1908).djvu/341

Rh state, will keep good in all climates. It can be melted in a carpenter's glue pot in the usual way and then weakened with water till it is of the consistence required. The quantity of water will depend on the strength of the glue, which varies considerably, but, in any ease, keep on adding as much water as will allow the glue size to set in the form of a firm jelly when cold, and if to one part of this there are added four of water, the result will be working size. Half-and-half can be made as before.

In moderately cool weather working size should assume the condition of a weak jelly when perfectly cold. Test the strength of it without waiting for it to cool, by the following means: Thin the strong size with water till about the right consistency. Then, after dipping your fingers into it, put them together a little while; if, on endeavoring to separate them they adhere ever so little, the size is properly made, but if they stick together quickly and rather firmly, it is too strong and wants weakening. If, on the other hand, the fingers separate quite freely, the size requires to be made stronger. This method of testing the strength of the working size is worth attending to as well as practicing; for if use is made of size that is too strong, your work will have a shiny appearance and the effect will be spoiled, while the colors would soon wear off if the size has been made too weak.

But should even carpenters' glue be unprocurable or not at hand when required, use leather or parchment cuttings, pieces of skin of any kind, or, in short, of any gelatinous substance that has no grease in it. Put them with water into any metal vessel and let them simmer till they are converted into a strong jelly, from which can be produced the same descriptions of size as those already alluded to.

As size does not keep well during the hot weather, when it gives off a very offensive odor, do not make more then than will suffice for the day's work. A little carbolic acid, however, mixed with the size will prevent its