DO NOT MELT TOO MUCH AT ONE TIME
As glue deteriorates quickly if allowed to stand, no more should be prepared than is needed for a single day’s work. It is even better to prepare it twice or oftener during the day.
If glue is dissolved at the proper temperature and kept at that same temperature after melting, no noticeable deterioration results during the course of the working day. But if allowed to stand over night its value decreases, and it should not be mixed with fresh glue, as it is not of the same consistency.
With practice and observation you can easily determine each day’s needs in advance and prepare each morning just the right amount.