When I last used liquid emulsion, I found I only needed a small amount at one time and don’t like the idea of reheating the whole bottle again and again to tap some off. So I heated it and then decanted the whole bottle into cassette tubs and stored them in a black plastic paper bag. In this way I could heat up only a small quantity at a time, as needed and none of the emulsion got heated more than twice. Perhaps this was unnecessary, I don’t know.