Anyway, the plaster patches on the back stairs are dry now - well, they were effectively dry even as I was putting them on the wall - and you can see how rough they are. A lot better than the holes they replaced, granted, but a disappointment.
The new camera can only hold ten pictures at a time (I haven't bought memory yet) so I needed to get this out of it to take pictures of today's plaster triumph. I started patching the front room in the carriage house. Here's what it looked like after removal of the previous owner's drywall mud. Click for the bigger picture, of course.
The upshot is: you can't really effectively patch cracks in plaster and brick with tape and drywall mud, so the patches are cracking, roughly three years after they were applied. I'm stripping off the worst of them and patching properly with plaster.
To mix the plaster, I started with a clean container: a Teflon-coated breadpan that had already been repurposed for geode cleaning. No stick = no crystal formation. I also added a splash of vinegar to the mix. The upshot was that it took a good half-hour for the plaster to start hardening in the pan, which was enough time to actually, you know, use it. I also cleaned my painter's knife and plaster trowel thoroughly before starting (and again after finishing).
And it worked! I've been scared of plaster's reputation as being a lost art mastered only in historical times by towering giants of the construction industry. It may very well take years to get good at it - but it took me two tries to get acceptably OK. I think some more tries will make me confident.
Pictures later. I'm going to go take them now.