I’m sure the tanning trade is the key. I had some notes on the tanning process as a couple of my ancestors were tanners, but the notes were lost when a hard drive failed; since learned about back-ups.
The hide has to have all hair and residual tissue adhering to it removed as the first part of the process and the raw hides are referred to as green hide and the removal and scrapping the hide to give it a regular thickness was the process known as shaving. You may have seen film natives of various countries scrapping hides or fur skins to clean off the fatty residues before drying the skins.
I can’t remember the details but I think the hide was soaked in caustic before it was “shaved”, it was very dirty and hazardous job as the workers were on plank walkways above the tanks of liquor.