Sodium carbonate sometimes called sal soda. A little goes a long way. Too much will actually dissolve calcium and not just grease & fat.

Don’t let your skulls boil or they will get chalky/flakey. Water somewhere around the 160 degree Fahrenheit mark works best for me.

Van Dyke's, McKenzie and evening Amazon carry Na2CO3. If you’re in a hurry Arm & Hammer washing powder is the same stuff just more expensive and can be found at Walmart or HEB.

I had started my own dermestid crew and just as I almost had the population big enough to start cleaning skulls we had the 7 hour long rolling blackouts with below zero temps which wiped them out. I started over and finally have my first skull being cleaned right now. A fox skull. My bugs still need to populate some more before I get to the hog and deer skulls, but I should get there by the end of spring or into summer. Question is after cleaning, what are you guys using for degreasing skulls before whitening them in peroxide? Especially the hog skulls.

With the water barely simmering, I use Dawn dish soap and Liquid Arm & Hammer laundry soap. Works great for me.