Q. I did not know to seal my marble stone back splash BEFORE applying a light grey grout. Now my white marble is stained grey from the grout! How do I get the grey color out of my natural stone please?
A. It's discouraging to see beautiful white marble change color after all that careful installation! Sadly, this is a very common issue with marble backsplashes. Before you tear it out and start over, there are a few things you or a stone restoration professional can try.
NOTE: Follow the manufacturer’s safety precautions when using chemicals.
From what you’re describing, the grey grout pigment has likely been absorbed into the surface of the marble because it was not sealed before grouting. Marble is a porous natural stone, and without a sealer acting as a barrier, grout pigments can penetrate the surface instead of staying on top where they can be wiped away.
However, what if you're seeing a thin film of cement and pigment left on the surface after installation called grout haze? On white marble, grout haze can easily give the appearance that the stone itself has changed color. Try this cleaning method, just in case. Use a 50/50 mix of ammonia and water to clean the tile. Not only can it remove grout haze, but it may also remove light staining.
If the gray color remains, then it is very likely that what you’re seeing is discoloration under the surface level of stone.
At this point, it would be best to contact a stone restoration professional. To find a vetted PRO in your area, visit www.surfacecarepros.com and click on Find a PRO. They can use a mild acid or acetone on the marble, which may produce better results for stain removal. However, more aggressive stain removal methods will need to be followed by honing and polishing to restore the finish. Your PRO can provide these services and also select and properly apply the most appropriate sealer for your marble.
To find a vetted PRO in your area, visit www.surfacecarepros.com and click on Find a PRO.
Article ID: 873
Created: January 27, 2026
Last Updated: January 27, 2026
Author: Fred Hueston
Online URL: https://surfacecarepros.com/kb/article/how-to-remove-grout-stains-from-unsealed-white-marble-873.html