Count me among those that did not know this. I have the Lee hardness tester and am working on a stand for it as I have a hard time holding it steady enough to get an accurate measurement. What I like about the Lee is it has an accompanying chart to show how much pressure the alloy can handle. It allows me to load it accordingly and before I had that information, I was just guessing.
I have an art supply store nearby and plan to acquire those pencils. Much quicker than the Lee or others. Most of my alloy is just a guess as I scrounge for material and that simple pencil test is akin to magnet testing steel alloys. Just dandy.
BTW, how does one subscribe to a channel? On youtube itself or another way.