stained granite slab shower walls

Dear Maurizio, Thanks for your service to consumers. I recently remodeled my bathroom and used tan-colored granite slab for the 3 shower walls. After a week of use, there appeared dark uniform staining along the bottom 4 inches of each of the walls. It turns out that the installer had not applied any sealer. We let the shower dry out for several week and before the stains went away. The installer then applied a sealer. We used the shower for a week before the staining reappeared much like before. However, there were four spots (3" diameter) that were significantly darker than the rest of the stained area. We let the shower dry out for 6 weeks. The staining gradually became lighter on most areas (though not completely gone). However, the darker spots remained dark and changed very little. The installer cannot explain this and thinks the granite is defective. Any advice you can offer is much appreciated. If it's helpful, I can email a photo. Thanks for your help. Brian

 

Dear Brian:

 

“ The installer cannot explain this and thinks the granite is defective. ”

 

Oh boy, now the granite is defective!!! That's a good one, alright!

Without actually seeing your stall, m only logical conclusion is that water, somehow, from somewhere, finds its way behind your slabs. Of course, the application of an impregnator (which is never good idea with stones installed in a wet environment), made so that the drying is much more laborious and may also have contributed to create those mysterious darker spots.

Check thoroughly all grout and caulk lines for possible entry by the water. Address any possible problem, let your stall dry thoroughly (hoping that also the darker stains will disappear) and then start using it again.

 

May I ask you now to please read and e-sign our Statement of Purpose at: http://www.marblecleaning.org/purpose.htm?

Ciao and good luck,

Maurizio Bertoli

 

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