Our painter used a water-based caulking product called Selleys No More Gaps to fill small cracks, e.g. along the edges of architraves. We now find that in many cases cracks have opened up. This is very surprising to me, since on the tube is written: "No More Gaps is a special formulation which results in a smooth finish, and because of its superior flexibility, those unsightly gaps and cracks won't appear."
Is this a common experience? How can it be avoided? I should add that I made a test of going over a cracked section with the caulking, and leaving it unpainted. It looked fine for a few days, but now I see that it has cracked again. Is this product just s**te?
When you say that it has cracked, how do you mean cracked? Is there movement taking place between the architrave and the wall? does the crack appear in the middle of the caulking, along one edge, or is it not adhering and starting to lift at the edges?
Its now the coldest time of the year, and any woodwork will be shrinking as your lovely insulated house takes that cold air, heats it up, and drops the humidity to an annual low value.
The caulk - it sounds like that is what you have, a version of decorators caulk - can cope with maybe ten percent movement. BUT crucially that's ten percent on the width of the caulk. If its been used to fill hairline cracks, its useless. Nothing will work there. Ideally you want several mm of gap and then it will hold up.
How big were the gaps to fill ? Too big a gap and the caulk will dry out to a certain extent and crack. Anything getting near to a quarter of an inch is too big IMO.
Commonly used in boatbuilding to seal the joints in teak decks and sanded down once set. I've used it in that application myself and it's easily sandable. MS-polymer sealants can also be sanded and overpainted.
I've used MS polymer sealants for repairing woodwork in difficult areas. For example in Italy we have an external door that faces the sun. The heating and cooling of that door is extreme and in the past it was a regular ritual to make good the cracking caused by movement of the door as it heated and cooled.
About five years ago I filled the cracks with MS-polymer sealant, sanded it and overpainted. No problem with cracking ever since as the sealant flexes with the door. I've used MS-polymer in several applications since then, for fixing skirting board in place, as a replacement for acrylic caulking and even as adhesive for constructing a wardrobe. Each of these applications is recommended by the manufacturer and I'd say that the performance was superior to Gripfill, Acrylic puttys and caulking and Polycell type fillers.
There are lots of places I wouldn't use it and yes it is slightly rubbery once set, but it's like vulcanised rubber (tyres) not like a low-modulus silicone.
Anyway, I'd agree with the OP, "No More Gaps" is rubbish as are most water based caulks and sealants.
You can sand anything, but does it give you a texture in any way resembling wood (which is presumably the idea)? If the paint can't cope with the caulk movement, there's not much point anyway.
:-) You are agreeing with my suspicion. What surprises me is that the painter uses it routinely. Perhaps this cracking happens routinely too, but by that time he's long gone, and maybe the clients can't be bothered making a fuss about it. I mentioned it to the guy (actually a friend, which complicates matters somewhat), and he promised to come and fix it up. That was quite a while ago. Obviously not a close friend.
The caulk is adhering well, and the cracking is in the middle of the caulk line. I don't believe it is caused by relative movement of the architrave and wall/ceiling - this house is solidly built, and I see no reason for such relative displacement. The cracks that were filled are very small, generally less than 1 mm. I am in NZ, where it is now summer, but the seasons are not extreme here, and it is humid at any time of year. The caulking and painting was done in mid-winter, but my test was done at the start of summer.
I'm wondering if the caulk was applied too thinly. The painter wiped most of it off with his finger. I don't believe it was sanded before painting, but then I saw cracking of the bare caulk in my test case.
Seasonal variations in the moisture content of the timber is enough to cause cracking. It's not just expansion contraction of the bulk but also warping and twisting as the moisture content changes.
1mm shouldn't be a problem provided that the gap is well filled and that the caulk sticks well to the substrate(s). Dust or flakey stuff should be removed. With a 1mm crack I'd probably deepen it a bit with a tool then fill.
Your'e not alone, i've used no more gaps on everything from small gaps (1.5mm) on interior architraves to larger gaps(4mm) on the exterior corner capping of my wooden weatherboard home, and without fail all work either cracked or the caulk shrank so much as to be completely useless at sealing anything at all. I've applied it in both winter and summer, tried only using a dry finger to smooth it, thinking i might have used too much water to smooth it. Nothing made the slightest difference, and i'm now left with some really ugly cracks under my finished paintwork....absolute crap product, wont be buying any selley's products again
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