The marble polishing powder I am using has discolored the pink grout. Why did this happen and can I fix the grout?

Some grout colors can be bleached by the oxalic acid in polishing powders. You are always urged to perform a small test to determine if this might happen. It is possible to recolor the grout. There are several companies that sell grout colors which can be painted on. But make sure you test the color to make sure it does not bleed into the marble and discolor it. If the grout joints are small it may be just as easy to scrape the grout out with a grout saw and apply new grout.

TIP Sometimes the color can be restored in the grout by applying linseed oil. Test in a small area before applying to the entire floor. Make sure linseed oil doesn’t discolor or darken the marble.