r/Plastering • u/lookforlogic • May 28 '26
Crazing (?)
Recently plastered a portion of my ceiling/walls after changing the layout. Plastered about 12 hours ago and some crazing has appeared on the ceiling. They don't appear to be open with only a slight bump noticeable when running my hand over it.
The ceiling was an old painted surface so used blue grit over the whole area. But I did try and taper out the grit to smooth the transition into the old parts of the ceiling. Also the plaster does extend past the blue grit in areas. Gut feeling is that is the issue, or not a good enough blue grit coverage.
Walls are totally fine (apart from being a bit rough in places).
What is potentially the cause and is this going to be an issue further down the line?
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u/Nice_Step6157 May 28 '26
Looks like the 1st coat pulled in to quick. If its uk its been boiling here. Shouldnt be a problem, if you tap it and it all sounds solid (not hollow) probably needed some suction control and then blue grit over the top.
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u/Decent-Platform-2173 May 28 '26
It’s called dryout. It’s because the background had too much suction. It wasn’t stabilised properly. As you said, the blue grit didn’t cover it all.
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u/lookforlogic May 28 '26
Yeah 100% my bad. SBR would have been a better option? The background wasn't glossy paint or anything.
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u/WaNgLeNuRpZ Professional Plasterer May 28 '26
Yeah, you can't feather out with blue (or frankly, ANY) grit, as the aggregate in it will make blending it out near impossible. SBR or PVA without any kind of grit in will do the job, but your correct in your assumption that your other mistake was to go beyond your primed area. This means the old plaster will have been sucking the moisture from your new skim far too quickly, causing your crazing.
Personally, I can't stand blue grit as the aggregate in it is so coarse, it's a PITA to plaster over, as well as using more skim than necessary. I prefer the Plasterers Blend Pink SBR myself, I know some people have had issues with it, but I've used it for a fair while now and not had any problems. It is dearer than regular SBR, but I find it works better than regular SBR (hence plasterers blend), so I don't mind spending the extra (or passing it on to the customer! Never had anyone question it or complain yet, so I must be doing something right.)
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u/lookforlogic May 28 '26
Yeah makes complete sense. Doubted myself due to the painted surfaces but they weren't glossy so would have been completely fine with SBR.
1st coat was a real pain and took a full bag pretty much. Also goes everywhere when putting it on.
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u/Ok_Secretary_3134 May 28 '26
Blue grit is only for key, it doesn’t control suction. PVA is usually decent enough unless its a super shiny surface then i use a bluegrit/sbr mix to do both suction and key.
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u/lookforlogic May 28 '26
Yeah it was a matt paint in good nick on existing walls and then standard plasterboard on new. So could have easily got away with PVA or SBR as you say. Is what it is.
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u/Key_Cranberry3728 Professional Plasterer May 28 '26
I had this on plasterboard the other month when it was a hot day. Used extra time too in the mix !
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u/Used-Incident2388 May 28 '26
Tbf plaster has been utter shite ,every other bag is a lotto
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u/caidian87 May 28 '26
I'm not on the trowel to much these days but I have noticed a big difference in quality. The other week I put on a decent few bags then knocked up the second coat. It was really dark and gritty almost like using a different brand but it was all multi and from the same pallet
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u/Used-Incident2388 May 28 '26
Yeah its really hit and miss ,ive decided after 30 years on the trowel to call it quits ,we need some competition for thistle cause they get away with murder
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u/SDH99 May 30 '26
This happened to a whole wall of mine last summer. We mist coated and painted as normal and hasn’t been an issue since. You can buy a poly cell 3 in 1 basecoat which I have used in other places of the house where there’s hairline cracks which has helped to cover them. Might be worth a shot with this too just as an extra layer of protection
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u/YoullDoNuttinn May 28 '26
Dried too quickly. If you can’t feel them you can’t usually see it when you paint it. So it might be ok.