We covered cutting edges in episode #61 but this one is specifically about cutting edges on flat moulds.
Cutting edges on appliance moulds do the work of separating the fine appliance edge from the flashing and excess, allowing the mould to close properly and achieve the feather thin edge you have sculpted.
The exact width of the distance between the cutting edge and the sculpted edge varies between artists and techniques, preferences and materials.
I have seen many sculpts where folk have had a massive distance between the cutting edge and the sculpt, and this is what prompted this episode.
The book I was reading which mentioned 'Stereo Type' with regards to printing was The Village Carpenter: The Classic Memoir of the Life of a Victorian Craftsman by Walter Rose, published originally in 1937. Check out the Stereotype process on the Wikipedia page.
See what books are freely available at Project Gutenberg https://www.gutenberg.org/.
-Stuart & Todd