Caulk help

30 Nov 2023
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United Kingdom
I’ve been decorating our lounge the past 5 days, we cleared cracks in the plaster out, filled with polyfilla, and caulked with “soudal decorators caulk” in the corners of the walls, and around skirting and dado rails.
This morning I’ve noticed that the paint is looking a different colour and hasn’t stuck well in places, and some tiny cracks in the paint are visible in places.
We’ve been using dulux walls and ceilings paint.
I’ve since read reviews of the caulk and seen negative ones with similar issues.
Is there any ideas on how we can resolve this? I’ve seen some people say use primer (i.e the zinnser one) over the paint where it’s darker.

I really don’t want to have to go back to square one.
And for future reference, any caulk recommendations that work fine with paint? Or is it always best to prime where caulks been used?

Lesson learnt for sure!

Thank you in advance

(Pictures for reference, also haven’t finished the job yet so don’t judge our painting skills lol and it’s our first house)


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I always try and leave caulk 24 hours before painting as this tends to reduce or eliminate the cracks in the paint, even though most caulks will say over paintable in an hour, or even less.
I've used Soudal a lot in the past because it's one of several in stock at my builders merchants, I stopped using it because it seems thinner than it used to be and shrinks too much meaning I have to go over it again. I use Everflex 125 (by Everbuild), reasonably cheap and reliable.

The staining is annoying, Zinsser cover stain will block it but expensive for a tin. Having dried it might be worth adding more coats just in the corners to see what happens.
I've only had the staining problem with grey paints for some reason but that could just be coincidence.
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I think I’ve had similar before with something I’ve used (think it was a type of poly filler), I wonder if it’s oil based and therefore showing through. I can’t remember what I did, might have just gone over it a few times.
Go over the caulk one more time with a small brush and the tiny cracks will disappear.
I had same problem with another caulk.
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Different paints react differently over caulks. Durable emulsion I found the worst at cracking although the quality durable emulsions at over £100 a gallon seemed fine most of the time.

Drying time and conditions also take an effect.
I used very little caulk and would powder fill first then prime, and only then apply a small amount of caulk and leave for 2 days to dry before painting.

I switched to polymer mastic but that needs 24h dispite the claims as that seemed best with no problems. Just not so easy to use.

Ask 10 people they will recommend 10 different caulks. It's just trial and error but give the caulk longer to dry will help.
Like @fillyboy my prefered caulk is Everbuild 125, Dow Painter's Mate if I run out of 125. Never been a fan of the Soudal caulk. Found that the edges seem to tear very slightly.

I know that a given emulsion is going to crack on the surface of the caulk, I coat it with shellac based paint first- Zinsser Bin or Smith and Rodgers Blockade, the latter being cheaper.
Some paints don't bond to caulk very well. Where you've caulked, prime it with a few coats of Zinsser 123. Also, caulk goes too hard and shrinks and cracks over time, use acrylic sealant instead.

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