Black mold/mildew on shower caulking

Old 11-25-05, 11:21 AM
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Black mold/mildew on shower caulking

Can anyone tell me if there's anything that can be done to stop this? My husband has tore off all the old caulking three different times now and recaulked and in no time at all we have black mold on the caulking again. It looks AWFUL and I'm embarrassed for anyone to use my shower and see it. I have tried a spray..I think it was called Tilex. It helped a little, but never removed the mold completely. Is there a special kind of caulking we should get or why is this happening so much/often. We have used the water resistant caulking too and still no better. Please help! Thank you
Old 11-25-05, 04:41 PM
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Describe your shower, completely - materials and where all the joints are, including any vertical joints/seams.

Tilex is a waste of money. Just use bleach. But bleach won't totally take away the black caused from staining into or behind the caulk. Often it is caused from water getting behind the caulk. Obviosly, even in recaulking, you aren't preventing this.

And just where is the mildew the worst? I have seen it in the caulk around the top of the tub, below mixer valves, because the mixer valve's valve stems leak water out of the stem and it runs down behind the wall, and onto the tub flange behind the caulk and uses the tub flange as a raceway to where all the caulk in the area gets mildewed, for example.

Other entry points are from neglecting the vertical seams as once in these seams the water will also get behind the caulk you have around the bottom horizontal. Another entry area is at the trim plates/rings around the hot and cold water controls or the one big single mixer plate (if that is what you have), or around the tub spout. People often fail to realize how much water picks on the 'head wall' from water bouncing back off your body.

In some rental properties where I have run out of time for a 'make ready' for new tenants (like college kids), where mildew is behind the silicone caulk, I have greatkly lightened it, to just splotches of light yellow color, rather than that black, by simply spraying bleach, repeatedly, over time, into all those areas that I figured the water got behind. In otherwords, I simulated, with the bleach, where the water got in at. Then, at some future date, I'd go back, strip the caulk, use hair dryer, get rid of the silicone caulk residue, and recaulk. ('Tub and tile caulk' works, also.)

Getting silicone caulk residue off can be difficult as even a brand new razor scraper blade will slip over the top of it! From what I can remember, I believe alcohol wil curl up/help get off the residue. And so does a highly concentrated citrus cleaner spray made by the Stoner Company, called Xenit. THAT is an excellent product and if anyone wants to know more, you can PM me.
Old 11-25-05, 05:35 PM
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A different type of caulk may help the problem. Now go to the CAUSE. Moisture is the perfect home for mold. You need ventilation in this room. A vent fan would do a lot towards prevention. I prefer the type that automatically run 20 to 30 minutes after the switch is turned off. Wiping down the area with a towel is also very helpful. Good luck.

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