Caulk Sucker
August 18, 2011 3:58 PM   Subscribe

Indoor/Outdoor Acrylic Latex Caulk around a tub - bad idea?

my eyes, of course, gravitated to the mold resistant caulk which was not called out specifically for bathroom use. Any particular reason why I should avoid using it on a fiberglass tub/ceramic tile joint?
posted by plinth to Home & Garden (5 answers total) 2 users marked this as a favorite
Check the drying time. Caulk labeled "bathroom" generally dries in 24 hours, but some exterior caulk can take a week. If you're caulking your only tub, that can be a problem.
posted by Daddio at 4:34 PM on August 18, 2011

Response by poster: 2 hour drying time, no big deal about bathroom contention. I'm more concerned with interactions with the fiberglass (melting it, not sticking) or lifetime issues.
posted by plinth at 4:36 PM on August 18, 2011

Best answer: If dry time is not an issue, go for it. When I recaulk certain tubs, I use outdoor rated clear silicon sealant. I just make sure to keep the bathroom fan on or the window open for a few hours to overnight after I apply it to make sure all of the fumes vent out. It might be worth making sure that you're using the low VOC stuff.
posted by Nackt at 4:40 PM on August 18, 2011

I am not a chemist, but here's what I have read about this: silicone caulks sold for use with ceramic tile are different from those sold for more general use. General-purpose silicone caulks are acidic. Portland cement, which is the binder that holds tile grout (and concrete and mortar) together, is alkaline and vulnerable to acid. General-purpose silicone caulks can damage the surface of tile grout enough to ruin the adhesion there. So, they make a special sort of silicone caulk that isn't acidic, and they market that for use in bathrooms.

I read this years ago on the John Bridge tile advice forums. The poster there had heard it from some sort of caulk manufacturer's representative.
posted by jon1270 at 5:25 PM on August 18, 2011

I find that silicone is preferable in most instances. Acrylic stuff seems to shrink and harden too much, silicone stays rubbery, and seems to usually adhere better.

No issues with fiberglass or ceramic. Silicone has the typical pungent vinegar/acetic acid smell as it cures.
posted by 2N2222 at 5:27 PM on August 18, 2011

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