Hello Partners,
Thank you in advance for any help you can give me to help this client.
A few weeks ago I asked for help to clean up grout stains on flagstone and Dr Fred said to use a mild acid and Stu recommended Klenzstone #4 or #5.  I did not get to that job yet, but I saw about 2000sf of mostly black slate yesterday and I am wondering if it should be tackled in a similar manner.  Some of the tile spaces are clean and others show a deposit (calcium?).  I was thinking of a medium, nylon brush as my tool.  I was going to do a test area with just water to see how clean I can get the slate without the deposits and other test areas with a recommended product to remove the deposits.  Any thoughts?

Thank You,
Barry V Raduta
Diamond Stone & Tile Care-South
Stone & Tile Pros