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.