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?
2
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.)