What is causing my white ceramic wall tiles to stain and how can I clean it?


I have 4x4 inch white ceramic or porcelain (not sure which it is) tile in my shower stall and very hard water that makes it difficult to keep clean. The rest of the bathroom is 1950s pink tile (walls and ceiling), but the white tile in the shower stall looks like it was put in later to replace some of the older pink tile. When I first moved in about 15 years ago, a few of the white tiles had a strange purple stain on them that I thought might be the result of past mold problems or damage from cleaning products. The purple color is ingrained in the tile and will not come off no matter what I try to clean it with. Now the problem seems to be spreading to other tiles, and the other day I noticed that the stain follows the exact same patterns across several different tiles. For example, one tile has a group of blotchy dots in the left hand corner, then a couple of vertical streaks, followed by more dots and smudges across the top of the tile. The tile next to that one has the exact same stain, and a few tiles away there is another tile with that pattern as well. It's like some kind of chemical reaction is going on in these mass produced tiles. None of the pink tiles in the bathroom have this problem, just the white ones. Do you have any idea what could be causing this stain and is there any way to clean or restore these tiles?


ANSWER - Since you don't see the purple stain in the pink tile, but you see it in the white tile, and you can't clean it, it sounds like you have a microbial staining or mineral staining showing through the white tile.

Although it is not common, some glazed wall tiles are somewhat translucent and porous.  The tile glaze is translucent so when the underlying tile clay body gets wet or stains it shows through the surface glaze.

There is a chance that the pink tile has the same condition, but the pink glaze is opaque so you can't see the underlying staining.

There could be a purple color microbial growth developing in the tile body that shows through, or it could be mineral staining.  Purple Cyanurate is a chemical/mineral imbalance problem, and is not an "organism" or algae problem.

Normally if you have a staining problem, it means you have a moisture problem.   Moisture is likely trapped behind the wall and there is some sort of organic food so that a microbial growth develops that will stain the tile.  Or it is a mineral imbalance that causes the staining.

To dry to remediate the problem you have to treat the problem, which is excessive moisture, and not the system, which is the stain.   If moisture is the problem then you have to stop the excessive moisture, which you might be able to do without tearing the whole shower out, or you might have to replace the shower   Stopping the moisture might not allow you to remove the stain because it may be trapped in the tile itself.

3 thoughts on “What is causing my white ceramic wall tiles to stain and how can I clean it?

  1. Maureen Kraus says:

    I have a newly remodeled (complete gut out) bathroom. In the shower 6 ceramic tiles are showing dark marks. Installation was over wonder board, waterproofing was applied and allowed to dry for days, a white adhesive for shower walls was applied and tile set. Appropriate grout was applied. Now months later, dark spots are showing on 5 tiles and a small pea sized bloom on one tile away on an opposite wall. The marked tiles are appearing on a corner seat front in the shower. Tile store claims nothing six wrong with the tile. I feel it is a firing or curing issue. The tile store will not give me the manufacture name or contact information as they say the manufacture makes the tile specifically for them and they will not release that information.
    A certified tile inspector was hired by the store to see our tile. He said there were no marks on the “attic stock”. He said the dark colored areas that are occurring on the tile and grout (I don’t see it on the grout), occurred moths after the installation and are installation related. Yet he did not say it was an improper installation!
    They offered me $245 to have the marked tiles removed. My installer wants $400 and then I need to buy the special colored grout. They also wanted me to sign off on the remaining tiles for future marking. I feel that the issue is related to firing or curing of the tiles. Also, workers at the tile store have told me they suspect the firing or curing to be the issue. The store sent me to claims. Claims denies any fault, the store manager said if I had not gone through claims, they could have helped me! So frustrating! Please, can you tell me if you have seen these dark spots on wall tile before? I thank you for any assistance!

    • Donato Pompo says:

      Normally stains on the tile surface are moisture related. If the surface of the tile is an impervious glaze then water should not migrate into it. Although there have been cases in the past where a glazed surface can have micro cracks that can allow moisture in it.

      If the tile body is an impervious porcelain clay body then I would not expect moisture to migrate up into the porcelain clay body. Although if you have a porous clay body then water can migrate up into it. There have been cases where contaminates in the thin-set adhesive or grout can migrate into porous clay tile bodies by transported through the water migration.

      They seem to be offering to fix the symptom of the problem without understanding the cause of the problem. If you don’t fix the cause then it can reoccur.

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