28 BULLETIN 1436, U. S. DEPARTMENT OF AGRICULTURE 
oil is not very effective. It is far from being the good moisture- 
resistant coating or filling that many manufacturers believe it to be. 
The shuttle industry needs an impregnating material more resist- 
ant than linseed oil to the passage of moisture. The humidity in 
textile mills varies considerably, causing much swelling and shrink- 
ing of the wood in the shuttles. As a result the manufacturer can 
never feel confident that shuttles will function properly in the loom. 
An effective impregnating material will materially better this con- 
dition. 
In Germany shuttles have recently been manufactured from such 
common German woods as beech, birch, and pine impregnated with 
hot liquid asphalt or paraffin compounds. These woods in their 
natural state do not make good shuttles, but the impregnation proc- 
ess is said to make them susceptible of a high finish. Though the 
work is still in more or less of an experimental stage, one concern 
claims to have sold several thousand shuttles made of the woods so 
impregnated. This firm has circulated literature illustrated with 
pictures of the treated shuttles. The possibility of successfully im-. 
pregnating other woods so as to make them as resistant to wear as 
dogwood and persimmon and at the same time moisture resistant 
should be given consideration by American manufacturers. 
GLUING SHUTTLES 
In column 6 of Table 3 is shown the relative difficulty of gluing 
dogwood as compared with several other woods. Manufacturers of 
combination fiber and dogwood shuttles who glue a fiber covering 
to a dogwood core often encounter difficulty, owing in part to the 
hardness and density of the wood. Extreme care in the gluing oper- 
ation is necessary to insure satisfactory results. 
The first requirement in gluing difficult woods with animal glue 
is a good grade of glue properly prepared. The glue solution should 
not be heated above 140° or 145° F. or kept hot longer than necessary. 
Fresh glue should be mixed every day or oftener and glue pots and 
brushes kept clean. 
It is important in gluing difficult woods to have the glue at the 
right consistency at the moment pressure is applied. It should not 
be so thin that practically all of it squeezes out of the joint when 
pressed, nor so thick or dry that the two faces of the joint will not 
come together under the pressure used. 
The consistency of the glue is governed mainly by the combined 
effect of the temperature of the wood and the glue room, the quan- 
tity of glue spread, and the length of time between spreading the 
glue and pressing. If gluing conditions are such that pressure must 
be applied while the glue is very thin, very light pressures such as 
25 to 50 pounds per square inch must be used. If a long time elapses 
between spreading and pressing and the glue becomes very thick, 
pressures as high as 400 to 600 pounds per square inch may be re- 
quired. Under average good conditions a pressure of about 200 
pounds per square inch should give good results. Further informa- 
tion about gluing requirements may be obtained from the Forest 
Products Laboratory, Madison Wis. 
When shuttles made with animal glue are used under very humid 
conditions, the glue is likely to soften and allow the joints to open. 
