Cracked Paint - On Skimmed Wall

Joined
20 Aug 2006
Messages
6
Reaction score
0
Location
Bedfordshire
Country
United Kingdom
After removing some wallpaper in my hallway, I decided so skim the wall to get a flat finish for painting, the plastering went surprisingly well & after sanding a few rough bits off I used B&Q Plaster Sealer as the pot of paint suggested. After this had dried I put a coat of B&Q emulsion on, this looked ok once it had dried but needed another coat. I then put a second coat of paint on 24 hours later & as it was drying, hairline cracks started to appear in various areas, including areas I had skimmed & areas I had not as only 1/2 the wall needed skimming. These crack have become worse over the last few days. I sanded some of the affected areas lightly, & the cracks dissappeared. But after I repainted, the cracks came back.

Can anyone tell me what could be causing this & more importantly, how to sort it.

Thanks

Mono
 
Sponsored Links
Joined
12 Apr 2006
Messages
1,080
Reaction score
6
Country
United Kingdom
What material did you use to skim ? What type of b&q emulsion did you use ? What was on the wall prior to plastering over (after stripping) ? Did you bond walls prior to plastering ?
 
Joined
14 Mar 2005
Messages
5,777
Reaction score
30
Country
United Kingdom
More questions..are the cracks in the paint or the plaster?

Im wondering if the emulsion hasnt taken to an oil based sealer...surface tension of the emul causing it to crack becuase it can get a grip.
 
Joined
20 Aug 2006
Messages
6
Reaction score
0
Location
Bedfordshire
Country
United Kingdom
Cheers Guys

In response to your questions.

Third_Eye
I used Wickes ready mixed plaster skim
It's B&Q matt coloured emulsion
After stripping the wall, uneven plaster remained
I didn't bond the walls prior to plastering

Zampa
The cracks are in the paint, the 2nd coat more than the 1st


A friend of mine reckons the B&Q plaster sealer hasn't done it's job & the plaster might be soaking up all the moisture causing the paint to dry to fast & maybe I'd be better sanding the paint back & using a PVA-Water mix to seal the wall prior to painting.


Thanks for the help.

Mono
 
Sponsored Links
Joined
14 Mar 2005
Messages
5,777
Reaction score
30
Country
United Kingdom
Dont...whatever you do try the PVA its an old wives tale..

Rub the wall down as much as possible an just re-coat it...that shuld provide enough key.
 
Joined
12 Apr 2006
Messages
1,080
Reaction score
6
Country
United Kingdom
Sometimes when using different Products Makes on top of each other, then this can sometimes cause adverse effects. i.e. you used 'wickes ready mixed plaster' then sealed with 'b&q plaster sealer' then emulsioned over with 'b&q matt emulsion'. Sometimes using different Makes can cause complications, that has happened to you. If you used all wickes Products then they would be liable. Maybe the paste that is behind the 'ready mixed plaster' has caused the cracking. What is the exact make and type of the 'matt emulsion' and what is the instructions on the 'matt emulsion'. Also, the thing about most ready mixed plasters is they are acrylic based !
 
Joined
20 Aug 2006
Messages
6
Reaction score
0
Location
Bedfordshire
Country
United Kingdom
Cheers for you help so far guys.

All I can remember off the top of my head is that it’s B&Q Calm Colours Matt for interior walls & ceilings. I also don’t remember anything different in the instructions to any other kind of paint I’ve used.

Before reading the post about PVA being an old wives tale I’d already tried it on a small part of wall but the results are the same. Also as I try to eliminate possible causes, I tried another kind of paint, since I had tester lying about, I tried, Dulux Once Vanilla White & that cracked too although not as badly, so it can’t be the paint I’m using.

I’ve also tried sanding the cracked paint back to painting again & that also hasn’t worked.

I’ve acquired a tin of undercoat so I’m gonna give that a go tonight on a section, although I don’t know yet exactly what it is, but my builder friend suggested it & I’m assuming he knows more about it than me.

Someone also suggested that it might be a ventilation problem as it’s a very small room & maybe I’ve not left the doors open for long enough. I dunno if this could be it.

I’m also waiting for B&Q technical services to call me back to see if they’ve got any clue.
 
Joined
20 Aug 2006
Messages
6
Reaction score
0
Location
Bedfordshire
Country
United Kingdom
The undercoat says it's idea for wood & metal but not for walls, so I think I'm gonna give that a miss.

Also, gonna have a go at watered down emulsion to "seal" the plaster. On another section of wall.

I hope I find the answer soon, coz I'm running out of bits of wall to try things out on.
 
C

confidentincompetent

Mono_Guerillo said:
The undercoat says it's idea for wood & metal but not for walls, so I think I'm gonna give that a miss.

Also, gonna have a go at watered down emulsion to "seal" the plaster. On another section of wall.

I hope I find the answer soon, coz I'm running out of bits of wall to try things out on.

Hi mono. Thinned emulsion on bare plaster is the perfect basecoat. (matt though). Sounds like your applying paint too thick on each coat, ths can cause Mud Cracking, are you putting paint on neat strait from the can?
On bare plaster thin by up to 20%, ( mist coat). The next coat make a bit more round (thicker). The problem here is each time you apply water based paint now, the cracks will reactivate (presuming paint coats thickness is the problem) I once got over this on a job by using solvent undrcoat (on the cracked emulsion. NOT ON BARE PLASTER) thinned with white spirit. will make quite a stink :evil: This acted as a primer sealer. Or another sealer I use on mixed substrates is Zinsser 123
http://zinsser.com/product_detail.asp?ProductID=11

good luck
 
Joined
29 Aug 2006
Messages
2
Reaction score
0
Location
Manchester
Country
United Kingdom
I couldn't help but give a cynical laugh when I saw this thread. I had my daughter's bedroom skimmed, allowed three days to dry completely, then as advised by the plasterer applied PVA to the walls - inspite of a long standing family tradition of using watered down emulsion. As soon as it was dry, within an hour, we slopped on the B&Q emulsion £12/tub.

After the first coat was dry we noticed a blister - no problem. Scrape it off and rub it down when dry! Apply coat of emulsion - what's this wrinkling around the edge of the paint line? Allow it to dry again and repeat the rubbing down then reapply more paint. Wrinkling appears again and the "fairy ring" is bigger! Repeat the process a few more times and the ring is now over two feet in diameter. Tried to seal the edge with Polyfilla to get a seal between the paint and wall, but the damp Polyfilla also wrinkles the paint. Then my daughter tells me that we have another blister on another wall - repeat the process and now have two large "fairy rings" of wrinkled paint!!! In the end we used four tubs of paint and still had two huge wrinkled rings on the wall about three feet in diameter, partly broken were I managed to cover with Polyfilla. I believe that I could have stripped all the paint from the wall quite easily with a pallet knife as it had not adhered to the wall. Took the paint back to B&Q for a full refund - good service. I now find that the paint is flaking around the top edge of the walls where I have over-painted with the B&Q ceiling paint!!!

Never again will I apply PVA to a plaster wall - new or old. PVA is good though for sealing porous bird baths :)
 
Joined
12 Apr 2006
Messages
1,080
Reaction score
6
Country
United Kingdom
To be honest "ron53", 1hour is not long enough to allow the PVA to dry. It should realy be atleast 4 hours, possibly 24 hours to allow to fully dry. Then again it takes 3 days to fully cure !. Also, did you thin down the PVA ? What type and make was the emulsion ? Did you thin down first coat of emulsion ? Also, the thing is, when anyone reads the instructions on PVA tubs it does not claim you can when painting ! It is most Plasterers & amateur "decorators" on the TV Shows. God the things these TV Shows people do is shocking and then the general public believe these people over an Pro Decorator, but that is image & good PR for ya, hehe. i.e. i was once told to apply matt emulsion over a side of a bath, as lady seen a guy who has his own TV Show do it, lol. I refused and she asked to me leave her home ! ! !
 
Joined
20 Aug 2006
Messages
6
Reaction score
0
Location
Bedfordshire
Country
United Kingdom
Third_Eye said:
What is the instructions on how to paint the 'wickes ready mixed plaster' ?

Firstly, sorry it’s taken me so long to respond, I’ve had a few problems with my PC.

The instructions on the plaster said “that the surface must be primed before painting” & that’s about all.

I tried a solvent based undercoat on one wall last week & it seemed to solve the problem, so I’ve repeated that on the other walls & it’s turned out great. Finished it on Saturday morning.

Thanks again for all your help and advice.

Mono
 
Joined
29 Aug 2006
Messages
2
Reaction score
0
Location
Manchester
Country
United Kingdom
Third_Eye thanks for the info'. We did water the PVA down, but as you say probably painted the walls far too soon. Also, we did not thin the emulsion because we had primed the walls with PVA. :oops:

My plan of action is to re-paint the affected areas in my daughter's bedroom with a solvent based undercoat as Mono_Guerillohas used above. Then re-emulsion the walls.

My daughter is moving into my son's bedroom as he is moving into a new home - we are skimming all his walls. No PVA, just emulsion and so far so good - no "Fairy Rings" or flaking!

Thanks for the solid advice on PVA and when I skim any walls in my own house it will be painted with emulsion only without the PVA. :oops: :D ;) :)
 
Joined
12 Apr 2006
Messages
1,080
Reaction score
6
Country
United Kingdom
Mono_Guerillo said:
Third_Eye said:
What is the instructions on how to paint the 'wickes ready mixed plaster' ?

Firstly, sorry it’s taken me so long to respond, I’ve had a few problems with my PC.

The instructions on the plaster said “that the surface must be primed before painting” & that’s about all.

I tried a solvent based undercoat on one wall last week & it seemed to solve the problem, so I’ve repeated that on the other walls & it’s turned out great. Finished it on Saturday morning.

Thanks again for all your help and advice.

Mono
I understand "Mono_Guerillo". Though i have done this myslef with Oil Based Undercoat but the thing is it makes your walls a fire hazard. Also, if u ever get a decorator to paper your Walls then explain that you have applied Oil Based Undercoat on Walls.
 

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Sponsored Links
Top