Why did my Gray Stone turn Brown after sealing it, and how do remove it?

QUESTION

I just had a professional install natural cut stone on the floor of my clients new shower. After it was sealed, the gray I selected, turned brown. It does not coordinate with the white and grey Carrara marble walls. Tearing it out would be a nightmare! I have read that stripping and staining porous stone is an option. questions:

What method do you recommend to change the color of the stone to grey?

Will striping and staining the floor lead to potential problems being that it is the floor of the shower.

Are there specific products you would recommend? Please advise. Designer In Distress.

ANSWER

ANSWER - Depending on what type of sealer you applied, it can enhance the natural color of the stone.   So perhaps the installed stone unsealed, or perhaps the sample that you originally selected, appeared to be gray in color, but in fact had a brown undertone.  The sealer may have enhanced the natural stone color bringing out the brownish undertones.  Natural stone is just that; natural.  So its inherit qualities will vary from shipment to shipment and from stone to stone.

You could have used a type of penetrating sealer that doesn't enhance the natural stone color and that would have given it more a natural look.  You should have had a mock-up made of the stone and sealed it to see the outcome, before sealing the entire floor.  In fact, the architect should have specified a mock-up prior to the tile installation using the specified and supplied tile, grout, and sealer that was to be used.  That way there are no false expectations of what you get, and you then have a chance to make adjustments.

You can strip the sealer from a natural stone.  It is best to you the stripper recommended by the manufacturer of the sealer that was used.  Otherwise you have to do some trial and error by experimenting with various strippers to make sure it works.

It is possible to stain porous stones with concrete stains, although it isn't normally done.   You do need to remove the sealer first so the stone is porous.  The stone needs to be very porous in order to accept a stain.  Dense stones don't stain easily.

Whatever approach you take, you need to test a small area out of the way to verify you are going to get acceptable results, before you apply it to the entire floor.

You can also hire an experienced professional natural stone restoration company who has experience working with situations such as this, which is what I would recommend.  Make make sure you check out the stone restoration's references.

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