Emulsion paint cracking crazing over caulk

Discussion in 'Painters' Talk' started by DIY_Has123, Sep 16, 2021.

  1. DIY_Has123

    DIY_Has123 Active Member

    I caulked between the ceiling and coving Saturday evening, and following evening I painted over with emulsion (leyland hardwearing matt with about 10% floetrol to reduce brush marks on coving). Have final coat still left to do.

    I used Nemesis decorators caulk from Screwfix and it had almost 24 hours to dry, although apparently its instantly paintable.

    Today I noticed the paint cracked/crazed along the caulk in some places. Maybe I applied too much caulk?

    Anyway I can sort this?

    Attached Files:

  2. Wayners

    Wayners Screwfix Select

    It's the paint more than the caulk imo. I use that caulk and most paints are fine but some of the durable emulsions crack like dulux easycare. The answer is to prime the caulk before you paint with a product you know will work.

    The other option is to use a siliconised caulk or polymer mastic as they never seem to play up.

    Prime over with BIN or bullseye 123 and when dry paint again.

    . What paint did you use out of interest?
  3. DIYDave.

    DIYDave. Screwfix Select

    Yep, a common problem, even though you’ve left plenty of drying time between materials, some paints just craze with some caulks

    Apply a thin coat of a ‘stain block’ type paint along where it’s crazed, allow that to dry and check overcoat times for the product

    Then touch up with the emulsion

    Zinsser BIN, 124, or Coverstain, although all have slightly different applications and uses, would all work well in this situation

    Good luck
  4. DIY_Has123

    DIY_Has123 Active Member

    Thanks Wayners.

    As mentioned used Leyland Hardwearing Matt Emulsion (white) with about 10% Floetrol and a very very small amount of water (about 25ml) to thin down. The purpose of the Floetrol was to reduce the brush marks on coving.
  5. DIY_Has123

    DIY_Has123 Active Member

    Thanks for the reply guys.

    I do have plenty of Zinsser BIN primer but hate cleaning up after as its shellac based.
    Obviously BIN is the superior primer but I also have plenty of Leyland acrylic primer undercoat....prefer this as its water based so much easier to clean up after. Would this also work well?

    Also been researching into this stuff and people say to ditch the decorator's caulk (no matter how expensive or high the quality) and go with acrylic sealant instead as its more flexible and would never crack/craze like decorator's caulk.
  6. DIYDave.

    DIYDave. Screwfix Select

    Whilst the Leyland Primer Undercoat is indeed a great product, it won’t help in this situation as it’s water based and you also need a ‘stain block’ type product

    As you have it, use the BIN - guaranteed end result

    As for cleaning brushes, you don’t need expensive thinners, just use methylated spirits, way cheaper and works

    Don’t even need that much, certainly don’t need to submerge the brush in the stuff, couple inches of meths in a small pot and work into the brush, this will remove and loosen the BIN

    Then wash in warm soapy water, then rinse clean

    Can even use the used meths again for the next lot of brushes you have, as a ‘pre wash’ if your doing more decorating, then need even less clean meths for the next wash, then again, finish with soapy water

    So ,,,,,,, BIN it, makes sense, emulsion over, you will be happy :)
    DIY_Has123 likes this.
  7. DIY_Has123

    DIY_Has123 Active Member

    Cheers Dave.

    Yeah its cleaning up after with the purple methylated spirits which I hate. But as you say will only need a small amount to work into the brush so will go with the BIN.

    So just one coat along the crazed caulk with the tip of the brush would do it you reckon?

    Also with BIN heard its really strong so tends to show through after the coat of emulsion...hmm I hope not.
  8. DIYDave.

    DIYDave. Screwfix Select

    Don't overthink the cleaning process with the bin,,,,,, 'hate' is a very strong word !

    Fair enough, if your talking about cleaning a 4" brush used with BIN, that's gonna take some effort and meths but, your talking about a 1/2" brush and just the tip

    I have had coverage problem using emulsion over BIN but that was with a cheapo emulsion, like water, so my fault

    Not used the Leyland emulsion you mention but sounds like its a washable / durable type (?) so will have more 'guts' to it than a standard emulsion so expect coverage to be fine

    1 coat of bin should suffice, feather out edges so no hard lines of paint once dried which will show through emulsion

    Let the Forum know how you get on :) .... and stop whinging about cleaning a half inch brush :D
  9. Wayners

    Wayners Screwfix Select

    Use clean spirit and yogurt pot and leave brushes for 48h. Will clean BIN, Coverstain, emulsion ect. No smell and nice to use. I normally then wash out with water. Smack brush on end of foot outside then dry in boiler cupboard

    Spray tin of BIN is handy to spot prime. Warm tin. When done turn upside down and clear nozzle.

    Avoid meths if possible but handy product
    DIY_Has123 likes this.
  10. DIY_Has123

    DIY_Has123 Active Member

    Haha yeah not hate but a hassle as opposed to cleaning directly under tap.

    The Hardwearing matt emulsion from Leyland is indeed supposed to be the most washable and durable emulsion but coverage is okay, not exceptional.

    Some spots where I easi-filled the coving joins for a seamless finish are showing through but this second final coat should do it. Plus I will be adding Floetrol so not sure how that affects coverage. @Wayners any experience using Floetrol?

    I'd say its certainly better than other emulsions where even after 3 coats people say another coat is required.

    Only thing I'm cautious of is the BIN primer is really strong stuff....complete obliteration!!! And I have read many times people saying the primer still shows through after several coats. i.e. flashing and the final finish not being uniform. Even though it will all be white white haha!
  11. Wayners

    Wayners Screwfix Select

    BIN is thin and no covering power so don't use other than blocking stains or adhesion primer, so on trim I top off BIN with acrylic primer.
    There are some primers you can use over caulk but not ones folks here will know other than bullseye 123 and BIN
  12. DIY_Has123

    DIY_Has123 Active Member

    So still yet to try it out this weekend but I contacted Leyland Trade and the guy there suggested to use a maximum diluted down emulsion and work into the cracking crazing in caulked areas before the next coat on top. Leyland hardwearing matt can be diluted down 25% water. So might give this a try first.

    Like I mentioned....cautious about using BIN to seal caulk as I've read so many posts online about people saying it causes flashing problems with many paints/emulsion on top.

    Oil based primer/undercoat other than BIN to seal caulk seems to be a good solution and may not cause flashing problems.
  13. DIYDave.

    DIYDave. Screwfix Select

    Well,,,, uv spoken to Leyland who make the stuff so I guess, they should know the technical side also

    But, if the full bodied paint has crazed against the caulk, personally, I can’t see how a diluted coat of same paint will solve the crazing issue ?

    Of course, I could be totally wrong here as after all, who am I compared to Leyland Paints :)

    Re. The BIN flashing, I’ve only had the issue once with a cheap contract matt emulsion - it just didn’t want to stick to the BIN

    Not had an issue when last used over a water mark on ceiling, went over with Dulux Supermatt and this had great covering power

    As to your Leyland Hardwearing, I would think that this will also cover over the BIN with no problems

    Obvious next stage (to me anyway) would be to do a test on a scrap of wood/plasterboard and hit it with a coat of BIN

    Allow to dry then over with the Leyland and see what’s what - simple quick test before you commit

    Interesting to hear how you get on / let the forum know pls matey !

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