Fig. 136.
The glue is heated by the hot water and steam of the outer kettle. [Fig. 136].
To prepare glue, dissolve the dry chips in water. It is well to soak them over night unless quite thin. If the glue chips are thin they may be barely covered with water and the pot set in the outer kettle of boiling water. Some kinds of glue require less water. The glue should be stirred occasionally. It should be used while hot and should be made thin enough to flow easily when applied with a brush. If the wood is cold it will chill the glue. Best results are obtained by warming the wood in an oven.
Prepared liquid glues, to be applied without heating, are common. As these glues thicken with age, due to evaporation, they must be thinned occasionally. In cold weather they chill and must be warmed in hot water to bring them to a proper consistency.
Fig. 137.
74. Clamps.
—Clamps are used in the making of a glue joint to expel the glue from the surfaces of contact, forcing it up into the pores of the wood or, if too much has been applied, out on the sides of the joint. For holding small parts, the wooden hand-screw is used, [Fig. 137]. To adjust this clamp, hold the handle of the shoulder spindle firmly in the left hand and the handle of the end spindle in the right hand; revolve them about an axis midway between and parallel to the spindles until the approximate opening of the jaw is obtained, [Fig. 138]. Place the clamp on the parts and screw the shoulder spindle up tight, adjusting the end spindle when necessary so that when it is tightened the jaws of the clamp shall be parallel, [Fig. 139]. In taking off this clamp, the end spindle is the one which must be released.