Not only overheating of the glue is prevented, but expense of supervision is reduced. The heater does not need to be constantly watched for fear glue will not be kept at correct temperature.
This particular heater is also provided with a brass agitator (hand or power) for keeping glue thoroughly mixed while melting, and with a special faucet by means of which the melted glue is drawn off without dripping or clogging. It is made in sizes from 2 gallons to 500 gallons liquid capacity, and for use with any heating agent—gas, electricity, or steam.
An apparatus of this kind not only facilitates economical melting of glue, by preventing evaporation, waste, formation of scum, sour and dirty glue, but it also insures uniform “spread.” Furthermore, it is a great incentive to accuracy and cleanliness on the part of workmen, encouraging them to good work by providing them with a neat and clean glue-melting appliance, in contrast with the old-fashioned, unsightly and ill-smelling “glue-pot;” and providing them also with glue that has been properly prepared.
KEEP STEAM AWAY FROM GLUE
Above all, keep steam away from glue. Some glue-melting devices are on the market in which glue is prepared by subjecting to the direct application of steam. This produces only bad results. All authorities are now agreed on this subject. It is safe to say that the chief development in glue-room methods of the past ten years hinges entirely on the discovery of these facts: that steam ruins glue; that glue never should be heated above 130° to 150° F. at the utmost; that the other properties in steam—boiler compounds, acids, dirt, pipe-rust, sediment, and grease—are absolutely injurious to glue.
Do not let the argument of speed blind you to the damage resulting from the live steam type of dissolver. If you want speed, use a type of instantaneous dissolver that prevents steam from coming directly into contact with glue. The very best practice, the one generally recommended by experts, is to heat glue slowly, with a heat not above 130° to 150° F. Then the glue is in the very best possible condition for work.
The effect of acids is such that they have been known to turn a pot of good glue black.
GLUE SPREADERS
In wood-working establishments where much glue is used, it should be applied mechanically, by means of glue spreaders.
Some spreaders are made with Brussels carpet covering for rolls, but this is not good practice. The carpet covering absorbs dirt quickly, is difficult to keep clean, is liable to tear, is sure to stretch and eventually rots and wears out.