8 BULLETIX 150 0, U. S. DEPARTMENT OE AGRICULTURE 
dry ingredients and requiring only to be mixed with water. "Wet- 
mix glues are made up by the user from the several raw materials. 
A number of formulas for wet-mix glues have been developed by the 
Forest Products Laboratory, 5 and some have been published. The 
use of prepared glues requires less technical skill than the use of wet- 
mix glues, although a standard procedure for the wet-mix glues can 
be acquired with a little practice. 
SOY-BEAN AND PEANUT-MEAL GLUES 
Vegetable-protein glues originated on the Pacific coast and are 
used extensively in the plywood industry of that section. Of this 
large class of protein materials the soy bean (JfO) and the peanut 
meal are typical representatives. Their glue-making properties are 
more analogous to those of casein glue than to those of starch glue. 
In preparation and use, the good-quality soy-bean and peanut-meal 
glues are similar to the casein glues. They are cheap, but have not 
yet proved to be entirely satisfactory for gluing all kinds of wood. 
VEGETABLE GLUES 
" Vegetable glue " is a term applied in the woodworking trades 
exclusively to glue made from starch. The properties of vegetable 
glues and the way in which they are manufactured clearly differ- 
entiate them from the starch adhesives classified as pastes. Vegetable 
glues have been used extensively in recent years because they make 
strong joints, are cheap, can be used cold, and can be kept free from 
decomposition and in good working condition for many days. They 
are impracticable for some uses becauses they are extremely viscous, 
lack water resistance, 6 stain certain woods, and set relatively slowly. 7 
Vegetable glues are made either from raw starch {29) or from 
processed starch. Some methods of manufacture of vegetable glue 
are patented. 8 These patented methods differ mainly in that chemi- 
cals added to the raw starch either remain in the glue when sold or 
are allowed to " process " the glue and arc then removed by washing 
or neutralizing. Vegetable glue may also be made from raw starch 
without the addition of chemicals. 
The principal raw material used in making vegetable glues is 
cassava starch, which is obtained from the roots of cassava, a tropical 
plant. This starch in edible form is more familiarly known as 
tapioca. Potato, corn, wheat, and rice starches can also be, and to 
some extent probably are, used as the bases of vegetable glues. Of 
these, potato starch is the most favored. 
5 Two formulas, developed at the Forest Products Laboratory and covered by United 
States patents Nos. 14r.(JS42 and 1291696, have been dedicated to the people of the 
United States or assigned to the United States of America. (See Appendix.) Butter- 
MAN, S. PROCESS OF MANUFACTURING WATKRl'ROOF ADHESIVES. (U. S. PATENT NO. 129] GOG.) 
U. S. Patent Office, Off. Gaz. 258 : 354. 1919. and Cooperrider, C. K. process 
OF MAXUFACTURIXi; WATERPROOF ADHESIVES. (U. S. PATENT NO. 1456S12J U. S. Patent 
Office. Off. Gaz. 310 : 1129. 1923. 
"Efforts have been made by private individuals to produce water-resistant starch glue, 
and some success has been reported along this line, but as yet no such glue has been 
offered on the market. 
• A vegetable glue said to be quick setting is now produced by one of the large vegetable- 
glue manufacturers. 
s BLOEDE, V. G. PROCESS OF MANUFACTURING VEGETABLE OEUE. (U. S. PATr.XT NO. 
1,357,310.) U. S. Patent Office, Off. Gaz. 280 : 21. 1920. Perkins, F. G. guub axd 
METHOD OF MAKING I'll: same. (U. S. PATENT NO. 1,020,655.) U. S. Patent Office. Off. Gaz. 
176:619. 1912. PROCESS FOR MAKING GLUE. (U. S. TATEXT NO. 1,020,650.) U.S. 
Talent Office, Off. Gaz. 176: 619-620. 1912. 
