New skim cracking (not blown)

[philipb82]

Hello

Yesterday i re-skimmed a wall over previous skim and as it was drying cracking started to appear. Now its dried there a few, i believe its called crazy cracking (the plaster is solid)? I pva'd to seal plaster 3 parts water and 1 part pva (stronger than tub instructed) then 3 parts pva 1 water for adhesion. When i skimmed over painted wall i didn't have this problem, im guessing its a suction problem? Anyway i really don't want to do it again can i paint then rake out and fill the most obvious cracks?

Thanks, Phil

 

[trowelmonkey1]

sounds like it's dried too quickly, sometimes a substrate needs plenty of PVA to control the suction so you may not have applied enough.

Did you find it was setting quickly?

 

[philipb82]

I think it may have set fairly quickly as it was warm in the room, I may not have applied enough PVA in that area too. The top half which I applied hardwall is fine and so is the bottom half. Like I said this is the first problem I've had with this, when I've skimmed over a painted wall its been fine!

I've been sorting out blown and cracked areas of plaster in the bedrooms and I thought I would have a go! I've been applying hardwall and skimming and then I'm replacing skirting boards...i'm learning I'm quite enjoying myself

By substrate, do you mean a bare surface like plaster or brick etc? Can it also happen if the mixture is too sloppy!?

Thanks

Phil

 

[trowelmonkey1]

by substrate i mean background.

Wetness of the mix will not be the cause, makes no difference, just personal preference as to how you like to have it to lay on.

Was the skim coat you went on top of unpainted? Paint can hold off the set, some types more than others.

I think you may have been better off having a closer to 5:1 mix for sealing, the 3:1 may have been too thick to absorb properly and may have sat around on top until you wet it with your finish.

 

[Micilin]

I thought I would have a go! .............i'm learning I'm quite enjoying myself


Phil

A word of warning - you'll be doing bits for mates next, and family. Then for friends of family, getting paid for it. Then you'll do more and more plastering.

Thenit will be too late. Your are on
The road to insanity...............

 

[trowelmonkey1]

never a truer word said Mic!

 

[philipb82]

Was the skim coat you went on top of unpainted? Paint can hold off the set, some types more than others.

I think you may have been better off having a closer to 5:1 mix for sealing, the 3:1 may have been too thick to absorb properly and may have sat around on top until you wet it with your finish.

Yes it was unpainted. The other walls i'm skimming are painted so am i ok with a 3 pva 1 water mix or am i better of with a 1 pva 5 water mix? I was under the impression that more pva is better for sealing. So a more watery mix is better for sealing especially for bare plaster? On the previous painted walls I've appled a 3 pva 1 water mix for sealing and then the same for adhesion and had no problems. [/quote]

I thought I would have a go! .............i'm learning I'm quite enjoying myself


Phil

A word of warning - you'll be doing bits for mates next, and family. Then for friends of family, getting paid for it. Then you'll do more and more plastering.

Thenit will be too late. Your are on
The road to insanity...............

I hope not!!!! I just want to sort out my problems in my house then have done with it. I'm enjoying it so far but my finish isn't the best so I wouldn't do anybody elses

Phil

 

[philipb82]

The walls i've skimmed over and will be skimming next are all painted with matt paint, if it makes any difference?

Phil

 

[philipb82]

Is it best to do a 5:1 water pva mix to seal the painted walls i'm skimming next?

Phil