Need DIY wall repair for puppy damaged wall.

If this is 19th-century style lath-and-plaster (as seems likely) repair requires a tradesman experienced in this ancient skill.

I would use Durabond 45 or 90 for a first coat. It's hard, setting-type joint compound that provides strength but isn't really sandable. Then use regular coumpound for a finish coat. Then sand it. You'll need a couple of spreading blades. The smoother you can get it, the less you'll have to sand.

| If this is 19th-century style lath-and-plaster (as seems likely) | repair requires a tradesman experienced in this ancient skill.

?? She said it's plaster over brick. Even if it were plaster over lath that's not a big deal. It can be taped, secured with ceiling washers and/or patched with drywall. Much of the work I do involves horsehair plaster, but I don't try to replace broken areas with more horsehair plaster. Actually most of it is a pretty good match for 3/8" drywall, so broken areas can be patched in easily.

If it's a small area you could Spackle it but you'd probably be better off with plaster. Plaster will not shrink and crack the way Spackle will.

An almost perfect match for repairing horse-hair plaster is a 50-50 mix of poly-filla and plaster of paris. It sets up fast and hard, and does not shrink. It is sandable, but feathers really well with the drywall putty knife. Being a "setting" compound it dries water proof - you can paint it with a water based paint without the patch softening, blistering, or otherwise misbehaving.

I agree. When doing the first coat with Durabond, do not let the patch stick our from the wall past the plane of the wall. If you do, it will be hard to sand that down. Then use regular joint compound for the thin finish coat. That is easier to sand smooth. Then paint.

P.S.. Aphoto or two would help. You can use