B leach is fine on limestone.....dilute it 1/2 cup clorox to a gallon of water and sop it on....Let it sit then rinse.....and have a fan and open window!

Thanks everyone. I am assuming those will come out. How long should I wait to clean the stone after applying bleach and washing off, then to add sealer? Would you guys suggest I polish this to some higher level to prevent mold again (semi honed/polished look).

You’re not preventing mold inside a porous substance thst wasn’t built correctly. It’s a sponge sitting there. It’s gonna mold until you redo it.

@User, I want to clarify your statement, please correct me if wrong:

1. The mold will stop via the bleach to a degree, but not fully: Yes, No?
2. The molding spots will come out restoring the finish again to the same color but not texture: Yes, No?
3. The stone has been penetrated with mold and cannot be brought back: Yes,No?
4. Will polishing it from its current honed state to a semi-hone/polish assist? Yes, No?

We are not in the position right now to redo that portion and want to restore/hold over for at least a year or two. I understand replacement is the proper choice, but what do you suggest to sustain? From what I am seeing, kill the mold and reseal with 511 or similar and try to get the entire shower.

We did not build the house, and I too would not have chosen limestone honed for the shower..

Stop using it if you want to eliminate the mold. Bleach won’t kill mold inside the stone. Concrobium will, but only the current infestation. Spores float around in the air, land on your sponge, and start growing. The only preventative is no moisture for it to grow in.

Thanks. If anyone can answer the other questions it would be much appreciated

Hi Eddie,

Unfortunately we have the same issue with limestone in our bathroom. I've had some mild success grinding down the stone with sandpaper but 18mths later it's pretty much back. I did apply some sealant that I think helped. I'm doing to grind again and apply sealant each day for a week and see if that helps carry me over a bit longer. Hope this helps.

Mark

How effective is your fan?

I have a Panasonic Whisper Fan which is automated and turns on and off based on ambient humidity levels in my bathroom.

My shower is completely dry in a relatively short period of time and there is no condensation on mirrors or shower enclosure. I also keep bathroom door open so that any moisture dissipates - my bedroom doesn't become humid.

I have marble in my shower and I have had no maintenance issues - mold or rust and have been using it for almost 3 years. It does need to be periodically sealed and I am due for that.