Pitting on overskims

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Mbk04

Mbk04

Member
Hi all, anyone got the cause and cure of pitting on overskims, its mainly when im going over artex. I don't have a pic but basically it looks a bit like acne..and can look uneven..no matter how much I trowel it it doesn't go. i know that it paints over fine but at certain light angles it makes the ceiling look s**t b4 it's painted.. also can a trowel be to sharp/ worn in your opinion?? Tia for any helpfull comments
 
Are you second coating with fresh gear? If not do that and leave the first coat to really firm up. Throw a few handfulls of bonding in the first coat to, that helps.


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I'm not really sure what you mean. If it paints fine I wouldn't be too worried. Plastering all to do with background and timing. Trowel can't be too worn in my opinion. How old is the trowel you're using?
 
Carbon steel trowels can get too worn in so to speak, I have one that’s about an inch and a half at the front up to two inches at the back it is brilliant for polishing but is a bit to flimsy to trowel up with out buckling and not doing what it meant to having said that it is fantastic for the curve under a staircase or anything similar. It is also over twenty years old
 
@Topspread16 yes, done all 3 of those things..only learnt the "special mix" recently on here. @JessThePlasterer the pitting is hard to explain really, and as you all know its hard to capture plaster accurately with a picture. i know it paints over ok as i've seen it painted.. i am wondering if its just that i'm using my fat too much to fill in and its the evaporation/ curing that is creating the effect??
@Vincey cant get on with plastic.. scratches too easily.. i can see the potentual of them tho
 
Seal your hi suck artex and the like first..
If it's those bleb ,bubbles your talking about?
 
Mbk04 said:
@Topspread16 yes, done all 3 of those things..only learnt the "special mix" recently on here. @JessThePlasterer the pitting is hard to explain really, and as you all know its hard to capture plaster accurately with a picture. i know it paints over ok as i've seen it painted.. i am wondering if its just that i'm using my fat too much to fill in and its the evaporation/ curing that is creating the effect??
@Vincey cant get on with plastic.. scratches too easily.. i can see the potentual of them tho
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Possibly re fat. I've found as I've gone along less and less need for fat
 
Fatarm said:
Seal your hi suck artex and the like first..
If it's those bleb ,bubbles your talking about?
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Bleb bubbles?? If it's blisters u mean then no not talking about them.. looks like pitted metal.. with very small, shiny pools of water probably only microns deep.. I will try to get a picture
 
Sounds like the artex is sucking in... done it before on a ceiling where you could feel the artex ripples on the skim.... i just pva and went over it again... but that was only once and it was a ceiling a chap i worked with had done and he was a tight chap so i put it down to putting the skim on too tight
 
Had this before myself skimming on to pva on artex, prefer blue grit now. Let the first coat pull right in and fresh second coat should avoid blisters and pitting.
 
Danny said:
Sounds like the artex is sucking in... done it before on a ceiling where you could feel the artex ripples on the skim.... i just pva and went over it again... but that was only once and it was a ceiling a chap i worked with had done and he was a tight chap so i put it down to putting the skim on too tight
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Yes, thinking about it it would kind of match the pattern of where the artex has been scrapped.. didn't put on thin tho.. strange.. I used to 3 coat with skim and let the first coat pretty much dry and don't remember having this problem so maybe it's just to do with not letting first coat pull in enough?
 
Mbk04 said:
Yes, thinking about it it would kind of match the pattern of where the artex has been scrapped.. didn't put on thin tho.. strange.. I used to 3 coat with skim and let the first coat pretty much dry and don't remember having this problem so maybe it's just to do with not letting first coat pull in enough?
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Where you scrapped the artex and broken through the paint you’ve created two different suctions so the plaster will be drying quicker over the scrapped parts than it will over the painted part. That’s what’s causing it.
 
Vincey said:
I meant the op guy mate , tbh I would be surprised to see any of the old timers change to plastic :numberone:
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I think you are right, it works for me, I can’t see the point of change for change sake only if it helps and after forty odd years although I have a few trowels at the moment to be honest not really had a lot over the forty years including ones that have been nicked, blown a hole in by electrics not properly secured and drills dropping on them
 
stuart23 said:
Where you scrapped the artex and broken through the paint you’ve created two different suctions so the plaster will be drying quicker over the scrapped parts than it will over the painted part. That’s what’s causing it.
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Yeah makes the most sense. .looks crap tho till its painted..hate it!
Maybe blue grit the day before is a better route
 
Mbk04 said:
Yeah makes the most sense. .looks crap tho till its painted..hate it!
Maybe blue grit the day before is a better route
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I don’t grit artex unless it’s had a few costs of egg shell, best option is to board but I know it’s not always an option, if it’s bare artex never been painted I give it a weak coat of pva then a strong cost maybe 2 strong ones depending how it pulls in, I also prefer to skim over fully dried pva not tacky on artex celings. A few on here use artex sealer but never tried it myself so can’t comment
 
Don’t scrape the artex and your problem is solved. With asbestos in it your not supposed to be scrapping it anyway without testing it. Normal artex will cover with two good coats and thicker stuff just use the 50/50 mix in first coat, saves time tiding up all the scrapings too.
 
Think I heard it called pickling on here before, it's when the less thick parts dry faster so pull/shrink back a mm or two and the thick bits are still wet then means when your trying to wet trowel surface isn't even so fat gets spread into those depressions...at least I think that's what he means, I'd leave the first coat for longer if it was me but don't know and had it before and it paints ok
 
stuart23 said:
Where you scrapped the artex and broken through the paint you’ve created two different suctions so the plaster will be drying quicker over the scrapped parts than it will over the painted part. That’s what’s causing it.
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yup :D

One way round that is it get the sander out and a light sand :D
 
Lodan said:
Think I heard it called pickling on here before, it's when the less thick parts dry faster so pull/shrink back a mm or two and the thick bits are still wet then means when your trying to wet trowel surface isn't even so fat gets spread into those depressions...at least I think that's what he means, I'd leave the first coat for longer if it was me but don't know and had it before and it paints ok
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Pickling.... good name that :D
 
I’ve just had this so came across this forum while looking for advice, i’ve just fixed it by soaking it and giving it a once over with my emergency ‘flonge’ sponge float and then troweling as normal, hope that helps!
 
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