Paint on New Plaster

[Craig1975]

Hello all, first thread so please forgive me if another exists on the same topic.

I have had my stair plastered a few months back and now started to emulsion paint it. i have done a light mist coat with homebase matt emulsion and then started another. Unfortunately a few areas the first coat has started lifting when going over with the second coat. How can i stop this happening?

Please help!!!!!!!!!!!!!!

 

[misterhelpful]

You say you applied 'a light mist coat' but what exactly do you mean by that?
A mist coat is a coat of emulsion that has been watered down approx 20-25%. Some will say more water, others less, but 20-25% is fine.

If you have done this, then the paint should have been absorbed into the plaster and should not peel off with subsequent coats, unless perhaps:

The plaster wasn't dry before applying the mist coat.
There was dust/grease/other contamination on the surface before applying the mist coat
The mist coat wasn't dry before applying the next coat.

If you didn't water down your mist coat then that is the most likely cause of the problem and I'm afraid you could find that a lot more will peel off with the more coats you apply.
Hopefully that is not the case and you will be able to get away with removing the localised loose paint and sanding back the edges to even out the surface before dusting off and re-applying another mist coat to the bare areas. Allow it to dry thoroughly and then start your next coat and it should then be fine.

BTW, Homebase emulsion wouldn't be a first choice to use as a mist coat; in the trade, Contract emulsion is generally used for this job as it contains no vinyl and is absorbed into the plaster far better.

 

[TheDec]

Could the plaster have been sealed with pva prior to the application of the mist coat, another possibility could be that certain areas of the skim were over polished, in which case a light sand would be all that is needed.

Dec

 

[misterhelpful]

Good point Dec, re: overpolished plaster.

I assumed PVA wasn't used when the OP said he used emulsion as a mist coat - hope it's not that!!

 

[TheDec]

Judging from what the op has said I doubt that pva is a factor, providing the op has followed the correct methods overpolished skim would be more likely.

Dec

 

[ic1927]

Why do some plasterers feel the need to over trowel so much, it's really annoying when you have to paint over "glass" like plaster. One plasterer on a job we were doing proudly boasted about how he liked to trowel his walls until they were like a mirror, I felt like punching him.

 

[Richard C]

Some self taught plasterers may be completely unaware of the problems it causes for Decs, remember many probably never get involved in anything other than plastering. A little enlightenment might help rather than “a good punching” which may well backfire on you as plasterers tend to be quiet fit & usually a have very strong upper body.

The other reason they may do it is if something you have done has ****ed them off!

 

[TheDec]

You have to admit though it is both annoying and frustrating when this happens, and it doesnt help matters to here a spread boasting about it. It might appear funny to him yet it can cause the Decorator both time and money.

Dec

 

[Richard C]

You have to admit though it is both annoying and frustrating when this happens, and it doesnt help matters to here a spread boasting about it. It might appear funny to him yet it can cause the Decorator both time and money.

As I also know the problems it causes, I don’t understand how any decent & informed plasterer would deliberately over polish if the wall is being painted; it takes rather more time after all. If someone does it deliberately being aware of the problems they are causing then they are a complete & utter knob & in that case deserve a thumping; just be careful your fitter & stronger than he is . If not, rap the edge of his finishing trowel against something suitably hard when he’s not looking.

 

[ic1927]

Richard, I have often asked plasterers not to polish the walls and most of them are tidy lads who know the score, but you will always get the odd one, as in any other trade, who doesn't give a damn about the next bloke. As for them being fit and strong, well, as a fifteen stone former amateur boxer I'll always fancy my chances if push turns to shove