Many years ago, when I spent time in the far north, I worked in a tannery that produced smoked moose hides. We used lime to dehair the hides and glutaraldehyde as a tanning agent. I really learned how to flesh and dehair hides there! It was smelly, heavy, wet work. But even though the chemicals were safe, I still wanted something simpler. Several years ago I regained the itch to tan hides. I experimented with battery acid, which is inexpensive, but somewhat dangerous to use. Another downside is that bugs will eat the acid tanned hides but ignore the brain tanned hide sitting on top of them.