Caulk won't dry in the shower -- too wet!
June 27, 2008 8:40 AM   Subscribe

The caulk along the floor of our shower had started to get moldy after a couple years in a new house, so we removed it and recaulked (with a "kitchen-and-bath" adhesive caulk). Worked great along three of the four edges -- but the fourth edge, along the metal frame under the shower door where the 1" metal frame meets the lip of the shower floor -- wouldn't seal (wouldn't even cure -- was still mushy) after 72 hours. Pulled it up, and discovered that although the area had been dry to the touch, enough water had still been under/inside the frame to soak a paper towel slid through the joint between frame and the floor.

There are tiny holes along the frame at this location, a few millimeters from the floor, presumably meant to prevent too much water buildup -- but we're guessing they also let some water in. There's also apparently a seam along the bottom of the frame which allows water inside the frame to seep into the join, and vice-versa. We soaked up all the water we could by leaving one paper towel after another in the join over the course of a week or so and a dozen paper towels, until they finally came out dry. Caulked again, and it seemed to cure a bit better (though the translucent caulk never turned entirely opaque -- just white in spots -- even after 48 hours), but the seal still didn't last more than a day's use. We can do the whole process again, but it's probably going to have the same problem. Tried a blow drier to dry out the area, but we don't have terribly high confidence of the effectiveness of that. Short of pulling the whole shower frame out -- which is likely installed with construction adhesive along with everything else -- any ideas as to how to get the area dry or how to get the caulk to cure?
posted by SeanCier to Home & Garden (7 answers total) 1 user marked this as a favorite
When I recaulked my tub I used rubbing alcohol just prior to application to remove all traces of moisture. I don't have the same frame/shower set up as you, though. But you still might add the alcohol as a last step after the paper towel routine so as to be absolutely sure there is no more water in/behind/under the area you want to caulk.
posted by hecho de la basura at 8:49 AM on June 27, 2008 [1 favorite]

Short of pulling the whole shower frame out

Huh well that was going to be my suggestion, but in light of that, are you using 100% silicon caulk? Are you sure the shower frame is installed correctly? Most have small slits that let them drain into the tub, not on the outside.
posted by Big_B at 8:58 AM on June 27, 2008

you could run a dehumidifier in the bathroom for a few days.
posted by jrishel at 9:08 AM on June 27, 2008

Assuming that the problem is a build-up of water inside the hollow metal of the frame, you could try drilling a few small holes into the outside of the frame at the bottom, to see if you can drain out any liquid.

You're on the right track though - get everything as dry as possible, remove every trace of old caulk (a razorblade is useful for this) and use rubbing alcohol or isopropyl alcohol to remove any last traces of adhesive or caulk.

Is your caulk acrylic-based or silicone-based? In my experience the acrylic stuff is second-rate. Look for a good (expensive) heavy-duty sealant that is specifically designed for showers. The 'kitchen-and-bath' grade is not really adequate for showers, where it may be subject to a powerful jet of water. That stuff is really just designed for the occasional splash.

If all else fails, there are sealants that are guaranteed to work even in wet conditions.
posted by le morte de bea arthur at 9:09 AM on June 27, 2008

You could have a leak in your shower pan that is allowing water to get
onto the subfloor. It could be around the drain.
Get under your house, if you have a crawlspace, and look at the subfloor
under your shower to test this hypothesis.
If you can't get under it, stop using the shower for a week or two, and
see if it dries out. Then use it, and see if it gets suddenly rather wet,
more wet than can be accounted for by seepage.
posted by the Real Dan at 9:18 AM on June 27, 2008 [1 favorite]

when you are finishing off, how are you smoothing out the sealant? If you are licking you finger and then smoothing I suggest a little bit of soap and water instead. I had some "mould" free sealant go bad due to this. Used the same sealant and its fine now.
posted by mefiskiing at 10:16 AM on June 27, 2008

sorry, just re-read the post and my last comment does nothing for the sealant not curing..... and with it being a new house you probably didn't do the original that went mouldy. but anyhow, when re-doing it avoid licking your finger to smooth it out
posted by mefiskiing at 10:19 AM on June 27, 2008

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