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How to clean mould on epoxy grout?

I had my shower floor regrouted 12 months ago with epoxy grout. Despite using a strong exhaust fan and routinely leaving the window open for good air flow as well as regularly cleaning and drying out the shower, this disolouration has formed. I'm assuming it's mould, which confuses me, as I was led to believe that epoxy grout was far more resistant to mould and that it could be cleaned easier. This discolouration is not budging. I have tried several different tile cleaners from Bunnings and nothing has worked.

Ideas anyone? Thank you!

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EricL

Hello @SamJones

Your grout is perfectly fine, what appears to be discoloration and mould is actually the actual colour of the grout. The trades person who did your grout actually did a very good job as they sealed the surface of the grout with a grout sealer. The light section of the grout is where the sealer has come off. If you know what sealer the trades person used all you need to do is to apply a new layer of sealer to the affected section and you'll get your uniform finish back.

The store does carry grout sealers such as the Dunlop 250ml Grout Sealer and the Betta TileCare 500ml Tile And Grout Sealer With Wheel Applicator. However, I'm not sure if it will produce the same grey finish as the original sealer. Since you've cleaned the surface thoroughly you can in essence apply the sealer direct.

If you have any other questions we can help with, please let us know.

Eric

SamJones

Thanks EricL. The colour of the grout is the darker colour, shown on the surrounding grout lines, so I'm not sure what you mean by saying the discolouration is the actual colour of the grout. This would imply that the sealer was coloured then which it wasn't. Sorry, but I'm still feeling a bit confused.

EricL

Hello @SamJones

My apologies for the confusion. When the sealer was applied it gave the grout a dark grey wet appearance, which is typical when the sealer penetrates the top section of the grout. Please note that this does not happen with all sealers, hence the importance of using the same one. As a quick way to verify that your sealer has come off, I suggest getting a metal scraper and scrape the section where the little grey sections are still attached to the grout, you'll see that they will come off, and you'll see the light colour of the grout underneath.

If your still wondering about mould infestation one way to directly test the surface is to use Exit Mould 500mL Mould & Stain Cleaner Trigger Spray. This is one of the most effective cleaners I've used, and it totally eliminates mould as I use it in my own home. Spray a small section of the light-coloured grout and give the mould cleaner a few minutes to activate. Rinse the surface off and wait for the surface to tally dry off. If it is mould infestation, then your grout should return to its original finish. If not then odds are the sealer has come off.

If you need further assistance, please let us know.

Eric

SamJones

Thanks for reclarifying Eric. I've just double checked with my husband and he has confirmed that there is no sealer on there as the trades person used epoxy grout which is typically not used with a sealer due to it being non-porous to begin with. And on the invoice we were given, it is mentioned that there is no sealer used due to the application of epoxy grout.

EricL

Hello @SamJones

If no sealer was used the next culprit will be limescale or calcium hard water deposits. I propose using CLR 750ml Ready To Use Calcium Lime Rust Remover. If you were to try to scrape the surface with your thumb you should be able to partially remove the lime scale deposit on the surface.

Eric

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