Blown plaster newly skimmed walls

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ma701ss

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Hi,

I've paid a good plasterer used before to skim over old lime plaster walls in my 30's house. The surfaces were mostly painted but not peeling and I rubbed these down. I applied Thistle Bond-it (green stuff with grit in, you probably know). All walls are OK except for one where the plaster has blown all over with crazed hairline cracks in all directions. It's no different to the others. I'm sure the wall was sound and the Bond-it went on fine. I can't figure out why this might of happened. I've worked in loads of properties where plasterers have skimmed over old walls primed just with PVA and don't think there were any problems after. Why in my own house with so much prep have I ended up with blown plaster?! So annnoying.:RpS_cursing:

Ma701ss
 
Possibly used uni finish, possibly distemper or paint work that was loosened by the pva, does the plaster come off the wall, does the paint come with it, did it dry very quickly ,the plasterer should of done his own prep work , possibly your fault..
 
Normally once the bond it has set and theres no problems it should skim ok. Common problems are listed above. Just one of those things to put down to experience. Very unusual to blow as the bond it acts as a barrier and key. Id chip it back to the backing plaster until your happy thats whats there is sound and flat, possibly pva and skim coat of bonding backing plaster before skimming again. Shouldnt have any problems after that. All us pro s get caught out now and again with these problems, I shouldnt worry.
 
all i can think is the suctions been so high when youve applied the bond it, its sucked all the goodness out of it and not worked properly, allowing the wall to react after skimmed when the water from that soaks in.
 
I think u have it right there a watery coat of pva wud absorb in the bond it could have lost all its moisture to quick ?? And ending up abit like a skin of paint on a Jew skimeed wall?
 
DannyMac said:
Was the wall one of the painted ones or did you apply the bond-it onto the fresh lime plaster?
Click to expand...

Wall was painted like the others. Just remembered I did go over a few large areas with a second coat of bond-it cos the first coat was a bit patchy. Might be why but it seemed pretty sound after. As the wall's mostly sound I'll probably line and paint/wallpaper over it. One thing the plasterer did say is that a lot of air bubbles blister up when applying the first coat on bond-it and it has to be worked hard, and also his lad did the wall on his own the next day...but I think he did the bulk of the work upstairs anyway and can't think what he'd have done wrong. Guess I'll never know....Thanks for the replies.
 
The finish of a wall is only as strong as whats underneath.

There is every chance that the weight of the new plaster could have pulled the existing plaster off the wall a little and caused cracking.

If you think of it....the average wall uses a bag of plaster and a bucket of water, thats at least 30kg of extra weight on an old plastered wall....
 
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