Why does my plasterboard patch have a rough texture?

Question

I'm performing a plasterboard patch repair and are in the latter stages.

NB: this work is a continuation of this post: How should I apply jointing tape when a patch is not properly inline?

I put in a plasterboard patch, fibreglass tape and then a skim of plaster (ready mix).

I then left it for a couple of months before doing sanding.

I was advised by a friend not to apply more plaster onto already cured paster as it cracks and was advised instead to use filler. I've used some ready mix filler and performed a couple of cycles of sanding and then refilling.

Now I see a texture (tiny cavities in the filler after sanding). I assume there is trapped air in the ready mix filler. If I keep sanding I assume there will be more of the same.

I'm wondering what to do next. I have some other filler "Tetrion", that is in powder form and I could mix that up and spread it on, to hopefully fill in the tiny cavities. Another plan would be to mix up some PVA diluted to seal the existing surface and apply more of my ready mix plaster (I don't think that has air bubbles in it, the texture of the liquid state is different). Would this look weird though when sanded with different layers visible like Damascus steel, and would the plaster bond properly to the sealed PVA?

Maybe I should do something else. I'd prefer not to go out and buy a completly different filling product as I already have plaster and 2 different fillers.

Thanks for any good advice

Answer 1

You are making simple things complicated. Yes, what you show in the pic was from air in the compound mixture. I "fold" mine back and forth in the tray to get the air out, before applying to the wall.

Get some All Purpose drywall compound. Fold it in the tray, ( I sometimes sprinkle in some water to lighten it.). Use a taping knife suited for the size of the area you are working with. Apply the compound and smooth it out. When it is dry you can lightly sand and everything will blend together.

I never heard that plaster over plaster cracks. It may, but I have not encountered this with drywall compound. Your information may be correct or not correct at all depending on whether plaster was actually used or was the term "plaster" used incorrectly in describing drywall compound.