It sounds like you guys are trying to goad me into posting this evidence and the documents, sorry but that is just not going to happen.
I would try to squeeze the guy who knew as well in order to get the goods.
About 100 years ago different terms and wording were used that we do not use today, everybody is barking up the wrong tree when doing research and looking for the answers.
Hand drawn pictures of these watches exist showing them with black cases, trust me.
I will go into the different methods used to get the desired results down the road (demonstration).
The term "black paint" probably needs to be tightened up and defined, which I will do.
It's one of those terms like "shrapnel guard".
No manufacturer ever called it a "shrapnel guard", it is just a VERY generalized term for "crystal guards", "watch protectors" and "mesh guards" which all means the same thing.