We just put in a beautiful honey onyx mini brick backsplash. We sealed it first. When we grout it, the onyx darkened and lost its glassy luster. What are we doing wrong?

 

Dear Linda:

For starters you did not seal your stone one bit: honey onyx is too darn dense to absorb anything (including the impregnator). So all you did was wasting time and effort while helping the retirement account of the guy who makes the sealer. That said, the darkening is probably due to the migration of the moisture from the back of the tiles that's coming to the surface. Due to the high density of the stone it will take a long time before the whole process is over and it will go back to its original color. As for the loss of gloss, it could be that maybe you did not remove the residue of the impregnator from the surface of the stone as you should have. That by itself could be the culprit, but it is also possible that the film of sealer trapped some of the grout as well. Another possibility is that the grout reacted chemically with the stone and etched it surface.

Leave it be for a month or so, and then, if you won't see an improvement, you will have to call a stone restoration professional to look into your problem.

May I ask you now to please read and e-sign our Statement of Purpose at: http://www.marblecleaning.org/purpose.htm? J

Ciao and good luck,

Mauri z io Bertoli

 

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