Black Stains on Grout

14 years ago

Hi - I had a new shower installed about 18 months ago which included full ceramic tile around the walls and a fiberglass base. I try and take excellent care of the keeping the shower clean - I squeejy all the tile walls and glass doors after EVERY shower and make towel off the grout joints where the tile meets the fiberglass base. Yet - in certain areas of the shower I get some annoying black stains on the grouted areas. I guess its mildew but am unsure. Its usually in the same spots. I clean them with a brush but they don't go away. I even caulked over those areas and they keep reappearing a few weeks later so I know its something I must be causing and not bad grout or workmanship. I keep wondering if there is something else going on that maybe I'm causing. The one thing that comes to mind is that I use a tile cleaner once per week called Kaboom. I sray it on the tile; apply a sponge and then let it sit for 3 -5 minutes. Could this be the issue? Could I be leaving it on too long (bottle says 3 minutes). Could it be ventilation? I do have a fan in the bathroom. If anyone has any incite, I'd appreciate it.

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Comments (5)

User
14 years ago
Was the grout sealed when first applied?

If not, or if incompletely sealed, you have mold/mildew. And it will not go away with 'cleaners'. You will need to use a mildewcide and then seal the areas.
frank1203
Original Author
14 years ago
Thanks for your response. To answer your question.. YES the grout was sealed when first applied, In fact, I sealed it myself. But also remember - I applied some colored silicon caulk over the grouted areas that had the stains and the stains still came back. I did not seal the caulk though at that time. Do you think this is mildew. If so - can you suggest a mildewcide?
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frank1203
Original Author
14 years ago
I'm still wondering if my overcleaning or the Kaboom Tile cleaner that I have been using weekly is contributing to this, maybe its not mildew??
MongoCT
14 years ago
Where is the mildew appearing?

Is it on a wet wall? The wall with the shower valve and head?

Does it appear high on the wall or down by the floor, does it form underneath shelves or bottle caddies?

Do you have a shower vent fan inside the shower? If so, when the fan is running, will it suck a paper towel up against the grill?
frank1203
Original Author
14 years ago
Wow, thats alot of questions. Let me try and answer..

(1) Where is the mildew appearing? The mildew is appearing mostly on the wall where the shower valve is and most of it is located down by the floor where the tile meets the Fiberglass shower base. Its only in certain areas on that bottom piece. I do have a couple other areas in the shower that have it and once again they are down at the bottom although I do have one area that is in the grout in the middle of the back wall. The wall with the shower head has the most.

(2) Do you have a shower vent fan inside the shower? If so, when the fan is running, will it suck a paper towel up against the grill? The shower vet fan is not inside the shower. It is located about a 2 feet outside the shower stall in the main part of the bathroom. And yes, it can suck a papertowel against the grill when running.

I am curious as to why you asked these questions. Knowing all this now, I'd appreciate your opinion and how to correct. You don't think its the cleaner I'm using?