Mysterious and stubborn mildew in shower - any recommendations?

[Adam]

Just a few months ago, I installed the tile in my bathroom. I took lots of care to make sure the grout filled all the spaces between the tiles, sealed the grout, and used caulk where walls met and where the tile met the tub. Now, as you can see in the linked pics below, this grey mildew is appearing only on the caulk. It only appears in this area, where the tiles meet the tub, and where water is prone to collect after a shower. I have been diligent about drying it recently, but regardless, I can't seem to scrub the mildew off. My questions:

1) Is this mildew coming from any source that I should be concerned about, aside from the water that collects there? 2) What can I do to prevent mildew from growing in the caulk? 3) How can I clean this stuff? Or do I need to pull the caulk out and re-caulk?

Thanks in advance for any help you can offer! Adam

[Dorot29701]

I am not sure Clorox is the answer. I had covered some perfectly good grout with some mildew resistant caulk that I was using when we installed a new shower door. Not long after, the caulk started turning gray and nothing I sprayed on it would bleach it out. I ended up having to pull out the caulk. The grout underneath was okay - not great looking which is the reason I covered it with clear caulk in the first place - but not mildewed either.

The caulk I put on the door did not mildew. Don't know why.

[Jmagerl]

My experience is along similiar lines as yours. New tile, new caulk = mildew. Once mildew starts growing on caulk , its in there. Time to scrap the caulk off and start over. The only way I got rid of it (partially) was to roll a paper towel into a tube, soak it in bleach, and lay it on the caulk. Then lay a piece of plastic wrap over that to retard drying. Give it over night to bleach out. Guess what: it came back within 2 weeks.

I ended up scraping out the old caulk, cleaning with a solvent, scraping with a razor blade, and then bleaching the clean surface and than reapplying new caulk.

I find that the type of caulk makes a difference. The worst was DAP latex tub and tile caulk. THe best (and whats been on there now for a year without any sign of mildew) was GE Silicone I. GE Silicone II was better than DAP but still eventually mildewed. MY theory is that anything with a paintable surface (DAP and GE Silicone II) will eventually collect dirt that mildew will feed on. GE Silicone I is nonpaintable and has a slick surface that nothing sticks too.

[Tony Hwang]

Hmmm, Used mildew resistant caluking? And no moisture build up in the shower? Maybe you used wrong type caulking. Tony

[Walter R.]

Just spray on a mild solution of Clorox (Household or pool chlorine). It will instantly dissolve the mold. To prevent future recurrences, spray it as soon as it becomes visible.

[Norminn]

You need to remove the caulk completely, clean the line with straight bleach, let dry, wipe with denatured alcohol. When completely dry, recaulk. Have to have a smoothe caulk bead so it doesn't collect soap scum and other shower detritus.

We just redid the grout in our shower. In spite of having scrubbed the tile a lot, I discovered the lower part, around soap dish, had thick soap scum. Got out the razor blade and scraped gobs of soap scum from the tile. After regrout and seal, we installed a timer on our exhaust fan so we can leave it on a while to dry out the room better. I also wipe the tile every few showers. With less soap scum, there should be less mold but your caulk looks like it had mildew under it when the caulk was applied. The room needs ventillation, as well.

[Tony Hwang]

Hi, Latex based grout stays well and does not change color. Tony

[robs67vw]

[pb]

[Adam]

The caulk I used is Color Caulk Premium Tile & Fixture Caulk. It has a picture of a rooster as the logo. Has anyone else had a bad experience with this brand? I will look for GE Silicone II in Bright While to match my grout, and it sounds like I need to scrape the works off and start over. Still open to any other opinions though.

[User Example]

I am not sure what the original question was but I have had excellent results with GE Silicon II caulk. Anything with latex in it should be avoided, based on my experience. I used to get cheap caulk but now I look for the most expensive and so far I am pleased with the results.

[CL (dnoyeB) Gilbert]

Bleach it for a few hours with waching machine bleach. That will remove the color. However, hopefully your caulk is color fast. sometimes the white can be bleached out and it will then be dull. I covered by shower in some kind of sealant that was supposed to stop this. I don't think it was worth a 8hit. Bleach it when it shows, and clean the shower diligently. Run the bathroom fan, and no pee in the shower...

[Adam]

OK, I did put some bleach-soaked paper towels on it last night and that cleared it right up! I will see how often it comes back, but that was a painless cleaning method, and smelled fine because I used lemony-fresh bleach. Thanks everyone!