I do a kot of brain tanning of all sorts of different hides and pork brains are what I always use. I've tried eggs , soap n oil, but the brains work better for me. And they come in 1lb tubs at the local grocery store for $2.49 a pop. The brand name is brookwood farms but I'm sure theres other brands where you live. Just make sure you smoke the hide whichever way you tan it in case it gets wet. You don't want to have to tan and break/stretch it twice. If your worried about evaporation soak in a bucket with a lid. The softening process is almost entirely mechanical I.e. stretching with all the primitive tanning methods and it is a lot of work but well worth it