I recently ran into a situation while working on my home. A friend helped me with some plastering but accidentally used joint compound instead of the right plaster, thinking it wouldn't go to waste. Now I'm seeing cracks forming as it dries and I'm unsure how to handle it. It's not exactly flush, and I'm wondering if I can just layer more joint compound on top or if I need to chip it all out first. Since I'm a welder and not really experienced in drywalling, I'm looking for some guidance on how to salvage this without it falling apart later.
4 Answers
You should be okay to just plaster right over the joint compound! The new plaster can actually key into the cracks from the dried compound. It might help to add some kind of adhesion promoter first. If you want to be safe, you could also take out a good chunk of the old compound and then apply the plaster, but you might not need to if you're feeling adventurous!
Using non-curing joint compound isn’t a great idea for this kind of work; it won't hold up for long. You really should knock out the bad stuff and use Dap patching plaster instead. It's actually easier to work with than joint compound and will give you a more reliable finish in the end!
Just add another layer of mud on top! Sand it down once it’s dried, and keep repeating until you're happy with how it looks. Once that's done, you can paint over it!
Regular joint compound struggles to stick to plaster properly. I recommend using 'hot' mud first, as it works well with plaster surfaces. After that, you can top it off with regular joint compound to finish it up. Just keep in mind that hot mud is harder to sand and smooth out, but it's worth it for a solid job!