Quote Originally Posted by winger
With liquid light, is it okay (or even preferred) to melt the whole bottle then pouring out what you need? Or can you melt just 'til you get enough for the amount of paper you're using? And if you open a bottle and use some, for how much longer will what's left be okay? A month or 2? months? years?
See my post on finishing.

When you heat an emulsion, you tend to restart the sulfur sensitization or restart the ripening process. This can be mitigated by the manufacturer by adding an inhibitor to the emuslion to prevent this. Also, the heat can start bacteria and fungi growth in the gelatin.

I cannot predict how your liquid light would be affected, but felt it fair to advise you to try to limit heat to nothing more than 40 deg C (68 deg F) and try to limit it to as short a time and as infrequently as possible. This is the only sure way I know to keep an emulsion for a long time.

There is nothing worse than the smell of a 'furry' emulsion covered with mold and starting to liqufy even in the cold. Unless perhaps it is an emulsion that has been fogged by repeated heat and cold cycles.

I put mine into wide mouth containers and can then remove what I need by using a large spatula or my hands (with rubber gloves) without heating the whole container. I just cut off chunks and weigh them until I have what I need and only melt what I need.