Fine cracks in new caulk
November 16, 2020 3:00 PM   Subscribe

I re-caulked our bathtub/wall joints, and now there are fine cracks in the caulk. Did I do something incorrectly?

I used the recommended caulk, with the recommended tools, at what I thought was the correct width (1/4" total). I completely cleaned off the old caulk, and dried out the joints. I even used tape to keep the edges neat. It looked great for a few weeks. But now, two months later, there are fine cracks in several places. I can't tell if they go all the way back through the bead. I'm not sure if they are a problem, but I don't want to have to deal with deeper mold issues, at least, not soon.

I've tried talking to someone at the hardware store, and looked online, but most of the suggestions are things like "use the right caulk", and the suggestions are what I used (silicone, etc).

All I can come up with is that I made the beading too small, and there was a lot of shrinking? But I'm not sure.

Handy home improvement MeFites, you're my only hope. What did I do wrong, or what should I do next time? And if there's some non-generic caulking resource I might have found if I'd looked more effectively, let me know that, too.

If it matters, I'm in Seattle, and the caulk was put down in...July? August? And I started noticing the cracks before our recent cold snap.
posted by Gorgik to Home & Garden (4 answers total) 1 user marked this as a favorite
Just to clarify, is the new caulk between the edge of the bathtub and the wall? If so, did you fill the bath with water before you put the new caulk on? You're supposed to do this to widen the gap to the max it would be during actual usage.
posted by EndsOfInvention at 3:13 PM on November 16, 2020 [3 favorites]

Best answer: I bet your caulk was not true silicone caulk but the kind that just has silicone in it. When you smoothed it, did it totally resist water or did it dissolve a little? I used true silicone caulk that lasted ten years, replaced with the blend and it cracked. Very annoying.
posted by HotToddy at 3:14 PM on November 16, 2020 [2 favorites]

Response by poster: AHHHHHH! I thought it was true silicone, and I did not read the container carefully enough. I'll go get some real silicone and do it again. Thanks!
posted by Gorgik at 5:07 PM on November 16, 2020 [1 favorite]

Once you put non-paintable silicone caulk on something, nothing else will ever adhere, including more silicone caulk. Use a paintable caulk if you can.
posted by rudd135 at 6:46 PM on November 16, 2020 [2 favorites]

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