I am so glad I took a risk and bid, sight unseen, on a classroom full of chalkboards. They're 3/8" thick, silky smooth, heavy as hell, and positively gorgeous. We had one casualty when removing them from the walls, but we still have plenty for our project (and we took the larger broken chunks for practice runs, so it's not all lost).
Removal was a lot easier than I expected. Some of the boards had been adhered with mastic and some with plaster. After we removed the quarter-round molding, the slates with mastic just leaned out - the mastic had long since deteriorated beyond usefulness. The ones with plaster required a tiny bit of prying around the edges. We got all 12 panels down in about an hour and a half. I spent the rest of the afternoon removing wood trim while Tom enlisted some help carrying the slate down to the vehicle. We were unfortunately not able to bring all the trim with us, but I think we'll be able to use what we brought home.
Behind the trim I found the signature of a construction worker, along with the place and date:
Cleves (OH) Dec 30, 1941
The drive home was stressful, but we made it with everything intact. So now we've got about 1,000 pounds of slate sitting outside in a borrowed trailer. Tom is supposed to be getting some help bringing it inside this afternoon. Now I just need to get my rear in gear and get some stuff done downstairs so I can actually use some of the