For the third time, I plan to remove this strip of caulk in my bathtub/shower a bit beyond the discoloration (mold?) and recaulk it. I would like to get it right this time.

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I plan to remove the caulk where it is discolored (mold?), clean it, let it dry for 24 hrs, and recaulk using Loctite Polyseamseal Tub & Tile, then let it sit 24hrs before use.

What else should I do to ensure this discoloration (mold?) under/in the caulk doesn't return? I thought I did it right last time, but obviously I didn't.

Also, is this the right sealant for this job?

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    You probably won't be able to prevent it with building materials. Instead, make sure you're ventilating your bathroom well, and consider a "clean shower" product to periodically apply an anti-fungal agent to the surface.
    – isherwood
    Commented Jan 6, 2016 at 14:39
  • The bathroom is ventilated well - the fan above it is working great. What anti-fungal do you recommend? How often? Commented Jan 6, 2016 at 14:42

2 Answers 2


Isherwood's right & make sure you're actually getting the blowing air from the bath fan on the outside of the house. Also, after showers or baths get into the practice of letting the fan run for another 15 or 30-minutes.

You just want to fill, actually fill, that crack below the tile is all. Squirt caulk INTO the gap & then force more caulk into the crack with your finger or a putty knife & repeat until it's full. Your closed palm should be facing the wall & not down toward the tub.

There's no need nor benefit in trying to make a ramp for the water. Water sitting on the caulk rather than beside it is mold's friend. Your caulk should look largely like your grout lines, it should be thin, tight & flush with the tile face.

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    Fill the tub with water before replacing the caulk and once you drain the tub, it should compress the caulk in the joint.
    – gbronner
    Commented Jan 6, 2016 at 15:45
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    Eh maybe, but this should be a fully settled situation by now. I think you meant to say the full tub would fully open the gap...not compress the caulk.
    – Iggy
    Commented Jan 6, 2016 at 16:09
  • This looks like a good resource, do you agree with it? naturalhandyman.com/iip/infxtra/infcau.html Commented Jan 6, 2016 at 19:12
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    Hey Patrick, yep that's a real good article & pretty much what I said, except the removal & clean-up stuff...you seemed like an expert there already. Jerry did a good job on the FILLING of the crack or gap. Though, I would've preferred a "good" picture or diagram showing the caulk flush, flat or inline to the tile face & completely filling the depth of the tile & a "bad" picture showing caulk ramped between the 2 materials & just covering the crack or gap. I also fully agree with yours & Jerry's Loctite Polyseamseal or 2 in 1.
    – Iggy
    Commented Jan 6, 2016 at 21:21
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    Yep. Looking like your grout just continued. That's why Jerry & I are saying to even do a 2nd or 3rd application. Caulk will never be as durable nor non-porous as the tile or tub. Those are where any standing water should be, not on the caulk.
    – Iggy
    Commented Jan 6, 2016 at 22:06

Squeegee your shower and shammy after each use. Also turn the bathroom vent on. My wife and I have been doing this for over 10 years. We never, yes, never have mold. The task is a pain but worth the effort.

  • Perhaps this is a function of the climate in your area. I have never seen a shower where this does not happen. Commented Mar 11 at 12:48

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