A note on food grade gelatin. If you do go that route, order it in bulk (i.e one big bag). Divide it among many small plastic bags, sealed tight. Keep those stored cool and dry, and then open one bag at a time. Photo grade gelatin manufacture and quality control is rigorously controlled. Food grade is controlled for bloom and safety, but the other constituents (that don't matter at all for food use but can have a big effect on emulsion making) can change from lot to lot. If you buy enough to last for a long time, you'll quickly learn its characteristics and eliminate gelatin as a capricious, and potentially confusing variable.