Paint Cracking When Drying

[PGibsonCoUk]

I have just finished painting a large bedroom and as I was finishing off the last coat on the last wall I reached the first wall I started painting tonight and noticed that it was starting to look like a dried out river bed.

The room was originally painted a very deep dark purple over 8 years ago. Because the purple was so dark and the new colour quite light I decided to cover with white first before I put my girlfriend's choice of "Mellow Mocca" over the top. Realising it was going to be a big job I thought I'd give Dulux's paint pod a go, hopefully making my job much easier, with the key thing being quicker as I knew I was going to have to do some of the coats after long days at work. On Saturday last weekend I put what ended up looking like a thin coat of "Pure Brilliant White" emulsion over the purple, on Sunday the second coat of white went on but the purple was still very pervasive. Over two nights during the working week I managed to get the third coat of white on and it looked fine, no hint of the purple remained. Satisfied I gave myself a couple of days off painting.

First thing this morning (Saturday) I put the first coat of Mellow Mocha on, it went on brilliantly but as I went around the room there were still small bits of white visible so I resolved to put another coat on, in hindsight that might have been my mistake. I gave the bedroom several hours to dry and decided to put the last coat on tonight (Saturday night). The paint says it should dry in 2-4 hours and it had been around 7-8 hours and everything felt dry so I put the second coat on glad that I'd finally be rid of the job.

I was only just finishing off the last wall when I noticed the first wall was starting to look cracked like when you see pictures of a river bed after a long drought. The cracks aren't exactly wide or deep looking but they are noticeable without getting too close and I'm worried it's going to look even worse in the morning.

My girlfriend comes back from a trip away in a weeks time and I had hoped to get another smaller room painted but it now looks like I am going to have to do something to sort out whatever I've done wrong in the first room.

Can anyone suggest what I've likely done wrong so I can learn from my mistake? Is five coats in the space of eight days the problem or is it that I actually got myself organised to start and finish two coats in the space of twelve hours? Everything was looking pretty good until I put the last coat on tonight.

More importantly what can I do to rectify the situation? I am very much an amateur decorator (that much may be obvious) so anything simple would be a godsend.

Thanks in advance to anyone who can help.


Cheers

Paul

 

[dcdec]

There's a few reasons why paint will crack like that, but in your case i think you've probably put the paint on too thick. It sounds like you've given enough time between coats but depending on the warmth of the room obviously drying times will vary. I think the paint pod thing has a continual flow of paint so it would be very easy to put the paint on thick.

All you can really do is rub down the areas that are cracked, fill with an easy sand filler (i use red devil), rub down, prime the filler with watered down emulsion (70/30 ratio) and then re-paint. Several thin coats are always better than fewer heavy ones. You'd have been better using something like zinsser coverstain to block out the purple, its expensive but makes up for it in labour time.

 

[PGibsonCoUk]

Well that certainly sounds likely, perhaps in my haste to get the job finished on Saturday I was rather heavy handed with my thumb on the button that delivers the paint to the roller. When it's going on so nicely, quickly and easily it's difficult to reign it in and slow down but I can see now what happens when paint goes on too thickly and/or if I go at a job like a bull in a china shop.

Trouble is I got so frustrated by the job, when the first coat of white dried it looked like I may as well have not bothered spend the past few hours slogging my guts out. I figured everythig would be fine after the second coat but no, still a fair amount of purple. By the time I'd put three coats of white over the purple I was so cheesed off with the job that I needed two nights of ignoring the job to keep myself sane and I was regretting volunteering to do it. Two nights probably was not long enough as I did the really half-arsed job on Saturday. The heating did click on after the sun went down and near the radiator the cracks are visible but nowhere near as bad as on the walls away from the heat source so that adds further credance to the theory that the penultimate coat didn't have time to dry properly before I applied the last coat.

I have attempted to add two images to this reply which should show the cracks, they are both closeups of the same section of wall, one with the flash one and the other with it off.

View media item 30633 View media item 30634
Acording to the Dulux website I can posibly fix the problem by applying one or two coats of thinned paint, although it does only say that it "may fill the cracks" so I don't know whether to try it. In the expert opinions on here, am I likely to make the problem worse or just be wasting my time if I try to put a thinned coat of paint over the top of the cracked paint? Or am I better off treating wall as described in the first reply and going from there?

If I do attempt it I won't be able to do it until tomorrow night so the walls will have had over 40 hours to recover from the last coat.

Thanks

Paul

 

[gomezbess26]

Hi, Ive read about your painting problem and i have a similar problem in my bathroom where i have painted over a dark blue bathroom paint with 3 layers of a lemon colour paint. Although I don't think I have put the paint on thickly a few days later I now have fine cracks all over the walls! I am interested to know what you have done to remedy this because i am thinking of sanding down the walls and applying a thin emulsion first. What have you done to get rid of the cracks?

 

[PGibsonCoUk]

I tried sanding the walls down. I spent hours doing it and on most of the walls the cracks were no longer there and on others they were very very faint but I couldn't get them any better. Happy with that I rubbed the walls down to ensure there was as little dust as possible clinging to them. I put another coat of paint on, manually and careful to be conservative with the amount of paint on the roller. Sadly all the walls cracked again after just the first coat. I was at my wits end at the countless hours spent and the amount of dust created and I had made no headway.

I did find a solution and that was to use something that perhaps I should have used right from the get go. I was recommended Polycell 3 In 1 Basecoat http://www.polycell.co.uk/products/polycell_3_in_1_basecoat.jsp, the description made me slap my forehead, if I'd known about that and put that on from the beginning I might have got away with one coat of basecoat and two coats of the desired colour, instead of the many hours messing around like I did.

I didn't even sand the walls down, I put the Polycell 3 In 1 Basecoat over the cracked paint and it smoothed it out instantly, one 5L tub did the whole of the decent sized bedroom. I gave it 24 hours to dry and put the first coat of paint on, which I had thinned out before the previous failed attempt (after the sanding). The first coat looked very patchy but it didn't crack. A couple of days later I put the second coat on, a proper (not thinned) coat and it went on beautifully, didn't crack and didn't require any more coats. I'm finally happy with the room and wouldn't hesitate to recommend the same solution for any room with a dominant colour that needs replacing. It's not a cheap solution but neither is it expensive and it makes up for it in the labour time saved. I have another room to do soon, I'll not be doing it for a couple of weeks but I'm very tempted to use the Polycell 3 In 1 Basecoat to cover the green before I go at it with the proper colour.

I hope you get similar success with whatever method you choose to remedy your issue.

 

[steveward205]

Hi, reading your post with same symptoms as i've had, stripped my bathroom ceiling back to bare plaster, applied 3-1 mix of unibond (as advised) then applied 3 coats of bathroom/kitchen paint.....horror the bloody paint is cracking in patches, i've fitted a new ceiling extractor aswell....can i use the polycell straight on to the cracking patches even with unibond as a base???? thanks
steve

 

[HumpyD]

Morning all.

You haven't said what type of paint was originally on the walls or what type of paint you are using.

You can certainly get this sort of cracking if you use matt emulsion over silk emulsion.

 

[dcdec]

Matt does crack over silk but it cant be that as he says he stripped the ceiling. Its because you used PVA to seal it.

 

[steveward205]

thought so, can i use the polycell product straight over the top of it?

 

[dcdec]

Anything you put on top of the PVA will adhere poorly, so its risky. You'd be better off trying to remove as much of the PVA as possible by dry scraping and washing.

 

[gomezbess26]

Thanks for your reply. I will definitely give that a go with the polycell underneath, anything is better than sanding down all the walls! so it must be because it was a matt emulsion on top of a shiny bathroom paint in my case. I also put some smooth it on the ceiling where the light fitting has been moved and then i sanded and painted over that, and that is cracking aswell! do you think i can put the polycell on that as well and repaint it?

 

[Jimbob88]

Gomezbess26 I realise this is an old thread but did the polycell work? I have the same issue I sanded back to the silk layer gave it a key put some dulux soft sheen instead on matt paint on but it has cracked. Really don't want to have to sand the walls down again. Many thanks.

 

[T_dot_white]

I had a similar issue and used a solvent based undercoat prior to overcoat in with Matt emulsion. Worked a treat

 

[Jimbob88]

Thanks T_dot_white I'll give that a go. Can you remember what brand solvent undercoat was? Many thanks.

 

[Neil the painter]

Just painted kitchen walls after the 3rd coat notice mud cracks on a 2ft strip down the middle of the wall so diluted gloss paint with turpes so it was watery painted over crackes the next day painted full wall again with 2 coats got up this morning and every we're apart from what I done with the gloss has cracked so thinning gloss down and painting cracks works just make sure do full wall lol not just cracks