sort of tangential, but this discussion reminds me of a recent conversation. we had a plumbing leak recently so we had to have these water damage mitigation guys come out and check all the floors and drywall and figure out what needs to get replaced, yada yada. and they've all got these things they call "moisture meters" which are little black plastic boxes with a digital display on the front, and you hold it against a surface and it shows a number that somehow indicates how much water is absorbed into the material. so I asked one of these guys "hey, how does that work? like what's it actually measuring?" and he gave a response that sounded in tone like a technical explanation, but the actual information essentially boiled down to "it tells you how much water is in there, and if it's above 20 it's bad." and I'm thinking like, yeah, I got that, I figured that out from hearing you call it a "moisture meter" and watching you use it for ten seconds. is that what you thought I was confused about? obviously I mean like, what quantity does the number represent; what are the units; what physical thing is being measured to generate that number; is it based on a physical property, a thermal property, chemical, electrical; you're using it the same on wood, drywall, carpet, insulation, how does it apparently treat all materials the same when they have different physical properties and absorb, hold, and release water in different ways? it just baffled me that I could have all these questions less than a minute after seeing one for the first time, but this guy who uses one professionally every day only needs to know water>20=bad