Tile and Grout Cleaning

[homeproud]

This has never happened before. We cleaned a home with white uneven Tile and Grout with GM. We pulled it all out, mopped with a neutral PH cleaner. The customer called back and said we left a few grout lines that were slightly discolored. We went back to get out the spots in question , using a acid rinse. Spots got better but still needs improvement
Any advice would be great.

 

[rob allen]

Have any pics? Did you use an acid rinse or an acid like Kick Acid? What did the stains consist of?

 

[homeproud]

Acid Rinse.