Cracking caulk as I paint

6 Mar 2011
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United Kingdom
We're painting a newly plastered room. The corners were a bit rough to I used caulk to smooth them out but the caulk seems to be cracking. I've painted with two coats of dulux trade supermatt emulsion. Cracks come back very quickly and are confined to the caulk.

Any idease great fully received? Can I somehow prime the caulk? Or should I really remove it?
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Thanks, it's the paint on the caulk that has cracked rather than the join between the caulk and the wall.
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The price should tell you all you need to know, and the spelling, which is an anagram of Sodaul. Silacryl is about as good as you can get and takes paint well, but its a trade item sold in boxes of 12 tubes for around £36, so if you want less you'll need to find a friendly decorator to supply you.
Ah! Thanks,

It was the more expensive of the two in the shop.

I also have some sdm caulk from Leylands. Do you happen to know if it's any better?

Can I just put better caulk on top or does it need to be removed?


Most caulks are made by only one or two companies so basically paint will often crack over them. The best way i've found is apply a coat of zinsser gardz over the caulk, you could also use bin, cover stain or oil based undercoat.

In future you could always use a lightweight filler applied with your finger
Used this many times myself and never had a problem with cracking before, how long was it until you painted over it? Maybe it wasn't dry enough or paint was put on to thick
Rather wish I had used filler.

Zinsser looks like a great product. But not sure where I'll find it open this weekend. Would a regular wood and metal undercoat be any good?

Are you sure you left it long enough? I've used 99p caulk and never ever had a problem yet.
This problem is often more about the paint than the caulk. Vinyl paints seem to crack more than paints with high acrylic resin contents (found in the more expensive paints), i should think supermatt is pretty much zero on this scale!

OB u/c normally works and the one you have is fine, apply it with the smallest brush you have and wipe off any excess, my preference is gardz as i've never had a problem with paint cracking if gardz is used to seal the caulk. I find it hard to believe that anyone who does a lot of painting has not had this problem at some point. You might be able to get the aerosol version of zinsser bin in B&Q but any sealer/stain block SHOULD work, you basically need a barrier between caulk and paint. Also worth mentioning that with new plaster you should apply the mist coat before caulking because the plaster will suck the moisture out the caulk

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