I had to take down the (plaster) ceiling in a stairway, and I'll probably use plaster when I put it back up. I've done some plastering before, but on 'virgin' walls. Here, I have to join it to existing plaster, at the ends and sides (inside corners). This is new territory.
I'm thinking to sand off the paint on the old stuff, wet it thoroughly, and then just put the new on as per usual. I'm concerned that this won't bond well, and a crack will develop. That wouldn't be the end of the world, but I'd rather avoid it.
The new plaster will be probably be Structolite, over sheetrock + Larsen's Plaster-Weld. The old is pretty thin - like 1/4", over wood lath. It has fine hair in it, so I suspect it's horsehair, though I wouldn't otherwise know one way or the other.
Any comments appreciated. Well, most, anyway.