Its still sold in the UK for certain culinary purposes, surprisingly enough.
As for why your experiments weren't as spectacular as you hoped: the particular charcoal you use is really important. Its best to make your own with a paint can, some willow, a nail, and a campfire.
Adequate crushing of components into floury powder follows, then adequate mixing, and ideally wet-pressing and corning.
The potassium salt is sold for curing meat from a fair few somewhat specialist providers in kilogram amounts, or in small bags from a fair few shops catering to Eastern Europeans.
Its actually quite fun to read the labels on stuff when browsing shops, you find all kinds of bizarre shit.
As for why your experiments weren't as spectacular as you hoped: the particular charcoal you use is really important. Its best to make your own with a paint can, some willow, a nail, and a campfire.
Adequate crushing of components into floury powder follows, then adequate mixing, and ideally wet-pressing and corning.
Source: an extremely misspent youth.