wall plaster repair
I have used regular Durabond (brown bag, not easy-sand) over brown coat. It works as long as the brown coat is not "crumbly". You might prime first with oil primer to seal it also. Build up with Durabond and skim with ready-mix. I've never resorted to plaster mix, but that should work. If the brown coat is not in good shape I generally cut it out too, add layers of drywall to get proper thickness, then finish....
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