# Tannin staining on porcelain tile



## eichlerfan (Apr 24, 2015)

I'm stumped and hope someone out there has run into this...

We installed a large amount of unglazed porcelain tile on a job. It was about halfway complete when the roof leaked. The roof is old T&G redwood, which obviously created quite a bit of tannin staining on the painted ceiling. 

The edges of the tiles are stained. We've cleaned them with water, cleaned them with an eco-green cleaner, then stepped up to an acid based cleaner, but an oily stain slowly creeps back up around the edges of the tiles. I'm sure it's tannins from the redwood. 

Has anyone run into this? Any advise or experience much appreciated. 

We are going to try taping off a test section, then sealing the bottom of the joint and the sides of the tile with a solvent based sealer. Hopefully this will lock the tannins into place. Obviously, we are holding off on grouting until this is sorted out.


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## MIKE ANTONETTI (Jul 17, 2012)

Basic drying process. So the tannins got into the Portland cement thinset, as you clean the Tile the tannins in Portland gets wet again, the dry air pulls the moisture up along with the tannins depositing it back to surface. The wicking process. 

What color will the grout be? A hydraulic cement grout will help lock the tannins in. It's basically designed for efflorescence.

I don't know how bad it got. I wouldn't use acid cleaner, that destroys the thinset. The carpet cleaning industry may have a tannin removal solution as they have chemicals specifically designed for Tannins. They have wicking issues with carpet as stains reappear.


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