Cant see what’s wrong with hardwall myself, better than browning was and not as much hassle as bonding, certainly a f**k site better than dot and dab. If you think it stinks now you should have used it in the late eighties
I honestly think there’s something in the animal bones theory. Doing a little bit of research, decomposing animals give off Hydrogen sulfide, Of which gives off a pungent smell of rotten eggs.
Would make sense. A lot of industrial waste goes into other processes. Fluoride for example