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Painting & Decorating

Peeling paint on new plaster

Hi. We have had extensive renovations and extension done recently. Paint is now peeling of most walls in all rooms. Convinced it is due to mist coat not being done properly, if at all.
Can I trust the paint which has not peeled not to peel in the future? Should we assume all paint will peel eventually? New ( proper professional decorator ) starting soon. The previous one ( employed by the builder ) has disappeared off the face of the earth.
Help

8 Answers from MyBuilder Painters & Decorators

Best Answer

This can be down to damp issues? Or not using correct paint I would look at the areas of where it peeling and the signs would be either wet or be coming through like mould if the probelm persist u would get a surveyor in to check it out

2019-06-07T17:53:49+01:00

Answered 7th Jun 2019

Paint peel can happen for a number of reasons. Assuming that your top coats are bonded to the suspect base coat, these are the main reasons I would check for if a customer presented me with the same problem during a quote :
1 : PVA/Unibond being applied too thick by the builder or plasterer prior to painting, which forms a skin instead of reducing suction/sealing, causing the paint to sit on the surface and peel as it cures (some emulsions dry within hrs but take up to 28 days to cure).
2 : Fine dust left on the surface by the plasterer not polishing properly or the decorator failing to dust down his sanding, with dust being bound initially by the 1st coat. Proper preparation would have highlighted this isuue. Again, in this case the paint sits on the surface instead of being drawn into the plaster, so peeling happens as the paint cures. This can happen whether the base coat was watered down or not.
3 : 1st coat of paint not being mixed with water for a mist coat and the plaster scorching the coating, forcing it to sit on top of the plaster instead of it sucking in and bonding to it. The paint then peels as it cures.
4 : The plaster was not dry enough prior to painting but this would be surprising! There are emulsions formulated for this situation but I don't trust them to deal with all the variables during drying! In this case all coats sit on top of the surface then peel as they cure.
5 : All other factors are good and proper procedure has been followed. However, before the mist coat sets (I like to leave to dry overnight just in case), subsequent coats of emulsion are applied. This can cause a skin to form in the new coating, forcing moisture to become trapped in the basecoat. As the moisture tries to escape, it lifts the paint from the plaster and splits it as it cures.
The same procedure can also drown a half dry coat, soaking away the bonds formed with the surface, leaving the base coat susceptible to peeling as the top coats cure.
6 : Water ingress from porous walls or a new leak. In this case you will see bubbling with white dust on top (efflourescence) and/or yellow/brown stains encircling the peeling paint.

All of the above reasons can occurr in small isolated areas without there being a larger inherent problem, so it isn't a guarantee that you will have complete coating failure over time.
I would say that if it is already peeling in large areas, the likelihood is that it is best stripped and redone properly. However if it is small patches here and there, particularly if mostly close to edges, there is at least a chance that extended drying times will prove the rest of the coating to be sound and workable.
I dare say that your proffessional decorator will investigate, then advise you as to the likely cause and proper remedy where needed.
Good luck!

2019-06-07T17:53:40+01:00

Answered 7th Jun 2019

Unlikely 'damp' in reality so cross that off.
Greens painting and decorating have given you great infirmation there, thats not cut and pasted off the internet but rather gleaned from years of experience tackling tough jobs.
I personally would take a punt at the paint that was used was not suitable for new plaster and was undiluted so the areas it has failed and is friable are the more dusty areas.
The 'good' areas, well it can be that maybe they wern't so dusty so somehow the paint did adhere.
You can usually tell by running your fingertips across the surface lightly and listening. If un- adhered it will sound light and hollow.
I use an super flexable filling blade thats been honed by 30 yrs use and 'get behind' the paint and it literally comes off in sheets

2019-06-07T17:53:33+01:00

Answered 7th Jun 2019

Definitely painted wrong didn't use emulsion and fallow the right specs or maybe he painted and the plaster wasn't dry enough

2019-06-07T17:53:58+01:00

Answered 7th Jun 2019

If the area was damp, you would of known this before decorating was done. Or at least decorator should of picked up on it.

The correct method is yes.. to apply a miss coat. I’m pretty old school..

WhenEVER applying paint to new plaster, I like to uni bond the new plaster BEFORE I miss coat. Doing this ensures the area is sealed and sound before paint is applied. This also helps prevent cracking. Just getting “getting the roller out” is easy... preparation takes TIME.

The longer you spend on preparation, the smoother the job will run.

Hope this helps.

2019-06-07T17:54:01+01:00

Answered 7th Jun 2019

Sounds like the decorator painted over wet plaster. New plaster needs 2-3 days to dry before you can even consider painting over it. The remaining paint will also likely peel off.

2019-06-07T17:54:05+01:00

Answered 7th Jun 2019

Hello.First the painter should use a contract white mixed with water for mistcoat.Not a top paint straightforward.
If the decorator do step by step the right procedure this paint reaction shouldn't happen.I recommend Dulux brand as i believe it is the best top coverage and really good finish.

2019-06-07T17:54:08+01:00

Answered 7th Jun 2019

Sounds like to me the plaster was not dry completely and then they used a vinyl or silk paint instead of using Matt and watering the first coat and didn't allow the plaster to breathe so the damp has been sealed in so it's trying to escape and that's why the paint is peeling off the wall it needs scrapping off and starting again

2019-06-07T17:54:09+01:00

Answered 7th Jun 2019

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