Bonding Coat Over Painted Walls

D

Doabsb3

New Member
Hi all,

I'm looking to plaster over painted walls and had a go on a small wall over the weekend. The walls are a bit lumpy/uneven so I've been using bonding coat to level and then multifinish.

I tried to score/rough up the walls to provide a key, then cleaned with sugar soap solution before applying 2 coats of PVA. Once tacky, I applied the bonding coat and skimmed same day. I left it nearly 48hrs only to find that it sounded hollow when tapping. The plaster literally fell away from the wall in large sheets and what was left behind was a wet, slimy mix of paint and a thin layer of bonding coat residue.

The paint seemed in good condition i.e wasn't flaking. I'm thinking now that maybe I didn't leave it long enough to dry through and adhere to the painted wall? The back of the "sheets" of plaster didn't seem completely dry.
Anyway, lesson learnt, don't try and cut corners! I'll now be scraping away all of the paint until I'm back to original plaster, however, I'm curious as to what happened?
 
Doabsb3 said:
Hi all,

I'm looking to plaster over painted walls and had a go on a small wall over the weekend. The walls are a bit lumpy/uneven so I've been using bonding coat to level and then multifinish.

I tried to score/rough up the walls to provide a key, then cleaned with sugar soap solution before applying 2 coats of PVA. Once tacky, I applied the bonding coat and skimmed same day. I left it nearly 48hrs only to find that it sounded hollow when tapping. The plaster literally fell away from the wall in large sheets and what was left behind was a wet, slimy mix of paint and a thin layer of bonding coat residue.

The paint seemed in good condition i.e wasn't flaking. I'm thinking now that maybe I didn't leave it long enough to dry through and adhere to the painted wall? The back of the "sheets" of plaster didn't seem completely dry.
Anyway, lesson learnt, don't try and cut corners! I'll now be scraping away all of the paint until I'm back to original plaster, however, I'm curious as to what happened?
Click to expand...
Sounds like you went over piss wet pva.

Listen, do yourself a favour and invest in a tub of pre grit and let it dry

Take a bit of the judgment out of the job.
 
I don't believe it. Bonding doesn't stick,or go off on wet pva . Porky pies . How many times we gotta say photos please.:endesacuerdo:
 
Doabsb3 said:
Hi all,

I'm looking to plaster over painted walls and had a go on a small wall over the weekend. The walls are a bit lumpy/uneven so I've been using bonding coat to level and then multifinish.

I tried to score/rough up the walls to provide a key, then cleaned with sugar soap solution before applying 2 coats of PVA. Once tacky, I applied the bonding coat and skimmed same day. I left it nearly 48hrs only to find that it sounded hollow when tapping. The plaster literally fell away from the wall in large sheets and what was left behind was a wet, slimy mix of paint and a thin layer of bonding coat residue.

The paint seemed in good condition i.e wasn't flaking. I'm thinking now that maybe I didn't leave it long enough to dry through and adhere to the painted wall? The back of the "sheets" of plaster didn't seem completely dry.
Anyway, lesson learnt, don't try and cut corners! I'll now be scraping away all of the paint until I'm back to original plaster, however, I'm curious as to what happened?
Click to expand...
You've found out that you can make the plaster stick to paint but you can't guarantee that the paint will stay on the wall , for the simple reason that the plaster is thicker and heavier than the paint. Also in your case the water in the pva and plaster has turned the paint into mush.
 
Bonding won't stick to some emulsions. Got a theory it's durable emulsions with the smooth surface. Odd though when it fails as sticks to everything you don't want it to like glass of gloss woodwork.
I apply PVA first and so far no problems
 
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