DRYING
The glue-solution from the boiling process is run into wooden troughs or “coolers,” about 6 feet long, 2 feet broad, and a foot deep, in which the solution sets in a firm jelly.
When set, a little water is run over the surface, the jelly is detached from the cooler, cut into uniform slices of the thickness desired, and placed on galvanized or linen nets to dry.
Drying may be done in the open air if weather conditions are favorable, or in a drying-room. The latter method is preferable. Conditions can be regulated to insure uniform drying.
Piles of the nets, or “stacks,” are loaded on trucks and taken into the drying-room, where they are exposed to the effect of warm air currents induced by blower or pressure fans, or exhaust or suction fans.
The drying is a source of concern to the manufacturer. It is extremely important to keep the temperature at just the right point, to protect the glue from dust and dirt, and to avoid the possibility of bacterial growth in the glue-jelly, which is very susceptible to the development of harmful organisms.
The final form of the glue will be in sheets, strips or flakes, or ground. For commercial purposes it is put up in packages, bags and barrels.
CHAPTER III
TESTING AND GRADING GLUE
There is as yet no uniformity of opinion among glue manufacturers and glue users as to how glue should be tested and graded. In a general way the manufacturer knows what kind of glue a certain stock will produce; but on account of variations that are sure to occur, it is necessary to subject each glue to certain tests, according to standards more or less definitely established.
The grades in general use are those originally employed by Peter Cooper, and are as follows:
A EXTRA
No. 1
1 x
1¼, 1⅜, 1½, 1⅝, 1¾, 1⅞
The only way to determine which is the best glue to use, is by trying out various grades in actual practice. The best glues for ordinary uses are well understood (see pages [79] to [85] for suggestions on this subject). Between two or more glues of any one type, actual experiment is the only safe guide. Most glue men will give you good advice; but above all, keep accurate records of results of the different grades used. When you have found the right glue, keep to it.