Paint not bonding with new plaster

DamoKen · 09-05-2014 1:42pm #1

Hi, had a plasterer in a couple of weeks ago to reskim the hall and landing, old house so walls were looking a bit battered. Plastering looked pretty good when he was finished so asked firstly how soon could I paint and secondly would I need to prep it before painting.

Told me to give it a week and no, could paint straight onto it. So followed his advice, started at the bottom of the stairs and as I got to the stairwell noticed a couple of times paint was coming off on the roller as quick as I was applying it. Had most of the stairwell done at this point so decided to leave it dry for a couple of days and see how a second coat went on.

Total disaster, while the hallway and bottom of the stairs seemed fine further up I painted the more of the first coat just lifted off the wall. Gave up in the end and called the plasterer back. He offered to paint it so I gladly accepted, advising him to sand back on the offending areas.

Anyway got home from work to find he'd ignored everything I'd said and used up over half the much more expensive finishing paint which surprise surprise just lifted off the walls in the same areas again. His parting advice to my wife as she paid for the work he had completed was if I find out what the problem is let him know, very helpful.

So I'm left with a stairwell that looks worse than before the plaster ever went on. The paint that's on is so loose it comes off in strips like wallpainter with a scraper.

The weird thing is the plaster underneath does not feel stable at all. If you press your hand against it your hand comes away coated in dust, that's not normal is it? Don't even need sandpaper to remove any scrapes from the scraper, just rub it briskly and hey presto, smooth again accompanied by a cloud of dust.

Any ideas? At this stage I'm thinking I've no option other than scrape all the paint off as with the number of coats he stuck up I'll never manage to even it out. Not sure what to do after that though, if the problem is the plaster he used or does it just need to be sealed?

Any advice welcome, head is wrecked!

onlyme! · 09-05-2014 2:09pm

Did you water down the paint to about at least 60/40 paint (mist coat) also what paint are you using, should be suitable for new plaster.

jack of all · 09-05-2014 4:25pm

Can you put up a few photos?

DamoKen · 09-05-2014 5:04pm

onlyme! wrote: »

Did you water down the paint to about at least 60/40 paint (mist coat) also what paint are you using, should be suitable for new plaster.

Unfortunately no, plasterer had said it was fine for painting as it was, only found out you should mist coat when I looked it up after the 3rd or 4th time the paint came away on the roller. I did do that on the final wall in the hall and probably why there was no problems there but was too late for the stairwell

Got the paint in a trade shop up in Ballymont that a lot of decorators use, they told my wife who got it that it was the best for new plaster, again though never mentioned mist coating. When the plasterer came back out he looked at it though and said it should have been fine.

DamoKen · 09-05-2014 5:08pm

jack of all wrote: »

Can you put up a few photos?

Hi Jack, can stick up a couple tonight. Looks a right mess now though. Originally was just a few patches, went to sand them back after the second coat started bringing more of the first coat off and once I started sanding it just kept coming off. Eventually used a scraper which brought whole sheets of it off.

Thinking as a last resort to just scrape back the lot and start again. Anytime it seems I've removed all the loose stuff if I try and paint again more comes off.

onlyme! · 09-05-2014 6:04pm

i'd say you'll be able to get it all off ok, which is good, you can get long handled heavy duty scrapers at your decorating shop which have a much sharper blade and work better than a ordinary scraper.

happy scraping!

United road · 09-05-2014 8:06pm

Hi Damoken.
I had a similar problem. What you are trying to do ls creat a "key"
I had the same issue and i am afraid to say that the more you paint the worse it will look. You could paint over and over, have layers of paint creating a think coat. But the issue will persist, your very first coat (undercoat) is not gripping the plasterboard. All subsequent coats are a waste of time.
As has been suggested, you need to scrape it off and start again, painful i know, but will be worth it longer term.
When you restart after scraping, you should first coat in primer. Also as suggested water this down first, then roll it on and leave it dry, i did a second watered down coat, (optional) then i put some undercoat on, finally followed by the overcoat. It worked perfectly.
This would be my suggestion.
It also goes without saying, once you have scraped off the paint, rub it down with a damp cloth to remove dirt, that dust you mention will not help create a sound key, to help grip your first primer coat.

Robbie.G · 09-05-2014 8:09pm

Clean off wall.Get Pva poly bond in any builders suppliers mix it with water ratio should be on tin paint walls with that first it will seal the walls and help the paint stick to walls.

game4it70 · 09-05-2014 8:46pm

As stated above,you need to scrape the non diluted paint you used off the walls as it will always be a problem every time you paint over it.

Dont use pva/polybond to seal the walls.That only makes more work for you and if put on to heavy it can peel like the pure paint you used.

Water down your 1st coat on the fresh plaster with about 1.5-2lts of water to every 5lts of pure paint.
The object is to let the watered down paint soak into the new plaster to create a key.When rolling it dont be tempted to go back over what you have just rolled trying to make it cover better.Let it dry for a few hours before putting almost pure 2nd coat on.
Also if you have to fill any scratches or nicks taken out of plaster from scraping old paint off touch them up with watered down paint when sanded.Pure paint can sometimes lift or blister if used over filler.

DamoKen · 12-05-2014 1:45pm

Cheers for all the replies guys, wasn't around at the weekend to get started, but yeah guessed there was no option but to scrape the entire wall back, was just hoping someone could provide a "simpler" option

Will start this evening, hopefully by the weekend I'll be ready to paint again!

mad m · 12-05-2014 2:19pm

Forget the roller, scrap off old paint and paint walls using a brush first. See how you get on with that first. Very unusal for that to happen.

DamoKen · 04-06-2014 2:26pm

Hi guys, well finally got enough free time to finish scrapping and sanding the walls so more or less ready to repaint.

Fair few unavoidable scrapes where paint had actually bonded with the plaster lifting a bit of it when I scraped it off so I've bought a bag of skim to fill and smooth where required.

Before I do though should I treat the wall on the areas that require some filling? The plaster on the wall is very very dry, clouds of dust even on a very light sanding so not sure how well any new plaster will bond.

Have a whole tin of polybond (neighbour had a full one in the shed) so should I water it down and brush it over the areas I'm going to skim?

Also would it be worthwhile after the filled areas dry completely to do a light watered down coat of polybond on the whole wall before repainting or should a mist coat be enough this time? Really really don't want to have to scrape it again so want to make sure it sticks this time around!

Cheers

650gs · 04-06-2014 4:34pm

You should never ever ever use poly bond on new plaster it just seals in any damp in the walls,
Remember plaster might seem dry but really takes months to dry out completely
so the best bet is to thin out paint.
As for the filling just wet the area you are about to fill and should have no bother

Sleeper12 · 04-06-2014 5:28pm

I'm afraid a few of the posters here are getting a little confused about Polly bond. Years ago a plasterer would have recommended using it on new plaster but this was back in the day of wallpaper. Polly bond gives a bit of grip for wallpaper. It should NEVER be used on a wall that is going to be painted. For a wall you are about to paint use bog standard ceiling paint & water it down as described above. The watery coat soaks into the plaster. You can fly through this coat. It doesn't have to be neat.

DamoKen · 04-06-2014 6:28pm

thanks guys, that's what I was thinking, seems to be more in favour of watering down the first coat or "mist coat" than the polybond but a lot on forums still seem to recommend the latter including my neighbour whose a retired plasterer who looked at me blankly when I suggested mist coating instead hence the confusion

Wallpaper instead of paint used afterwards makes a lot of sense for this approach, thanks for the explanation for this preference tpmcompany1, hadn't seen any before!

I'll go with dampening the areas to be filled as suggested by 650gs prior to filling and then once it's all dry go with the watered down paint.

Thanks again guys, very helpful

Paint not bonding with new plaster

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