New Marble Floor Tile Turns Green

by Paul Sinclair
(Manchester, England)

green colour marble floor tiles

green colour marble floor tiles

QUESTION:

In summer 2008 we had a new house built in Cyprus with high quality marble floor tiles throughout.

The colour was mainly pale shades of beige/yellow with brown and red lines and colouration. The appearance after the floors were laid was high gloss. Cleaning was with pure cold water only.

After about two months some of the marble floor tiles (perhaps 20%) started to show a strong green colouration on the surface.

This could not be removed with cleaning compounds.

Removing one tile showed that the green was in the top 1mm of the tile and not throughout the depth of the tile.

The builder used a contractor to grind the top 1mm off all the floor tiles - the grinding operation was a wet grind with a second machine removing the water slurry. It took seven days to do all the floors in the house. Finally all the floors looked perfect.

Unfortunately, after a further two months the same green colour had returned to those same tiles.

It is not all the marble tiles that are affected and only the original ones that have gone green a second time.

Does anyone know why this might happen, what is the cause? Any advice would be appreciated. Regards, Paul Sinclair

ANSWER:

Paul, I can feel your frustration. A very puzzling problem for sure.

First, you must rule out that there isn't any source of moisture underneath the marble tiles. If the sub-floor was not sealed then you could have moisture wicking up through to the marble.

Now I know you stated that the "green" is only on the top 1mm, so it would seem that it is not a moisture problem from beneath the tiles or you'd likely see evidence through the entire thickness of the tile (I agree and think this is probably not the cause).... but you need to rule it out.

My best guess is that your marble contains copper ("brown and red lines of coloration") that is being oxidized and turning green as copper does when exposed to air and moisture.

Obviously, since it's a natural product some tiles will contain more copper than others, which would explain why it's occurring only on certain tiles and the same tiles after re-surfacing.

The same type of problem can occur with white marble, which often contains iron. When exposed to moisture the iron rusts, leaches through the marble and causes brown/yellow/orange stains.


With white carrara marble and iron the problem usually occurs when water is behind or underneath the tile and leaches through to the surface.

Another reason stones turn green is when accelrants are used in adhesives to make them dry faster.

We see this mostly in marble and granite countertop installations where green spots appear on the surface shortly after installation and/or the granite slab seam edges turn green.

Such accelerants should not be used precisely because of this problem.

The green spots don't occur in all cases and sometimes the green spots will fade on their own... or can be treated (and removed) like a typical granite-marble stain.

Often though, it is a permanent problem, since the glue leached all the way through the granite countertop from underneath where the adhesive/accelerant was used... and can continue to leach through for a long time.

I don't think this is the reason for your problem with the marble floor tiles developing the green stains.

If it was due to use of an accelerant it would likely be seen over the entire floor.

Given the extent of the problem, I'd say your only good solution is total replacement. Or learn to like it.

It may have been possbile after re-surfacing to apply a topical coating or wax (not the standard impregnating sealer that is most often used on stone). A topial sealer/wax would keep air off the stone so the copper wouldn't oxidize.

However, permanent topical sealers require a lot of ongoing maintenance. They scuff and scratch and get dull. Also not good to suffocate the stone, so such topical treatments are not generally recommended for application to natural stone... especially on a floor.

I know green wasn't a color you had picked out, but honeslty it doesn't look too bad in the picture. It looks natural to the stone with a similar tone in color and not really like a stain or blemish.

I understand that it may look horrible in person, but I can't say the installer is to blame here, so if you don't want to pay for the job a second time then with lemons... make lemonade.

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Green Leaching through on Granite
by: L. Anderson

Hey, I am having the same problem with granite counters. We have had them for four months. Green is leaching through on edges, near seams and on top. The granite is Golden Splendor. Thanks

====ANSWER:

Near seams, etc. is likely due to the glue used leaching into the granite from the seams and from underneath. Sometimes an accelerant is used that results in this problem.

These stains are not easy to get rid of and may be permanent since the source cannot be removed. But the only chance you have is to follow the instructions in the Removing Granite & Marble Stains ebook.

Good Luck,
Ryan

L. Anderson Please Help
by: Anonymous

I noticed your post. We are having the same problem with our granite and it goes by a different name, but I believe it is the same stone you have. We just had our countertops installed and the edges have been getting greener and greener.

We are just getting into this, but I believe that the reaction is chemically based and not due to air oxidation. To my knowledge, this granite doesn't contain a lot of copper and that doesn't explain why only the edges are green. Is there anything that you found out that you can share with me?

Green Leaching Through Granite - Help
by: Ryan

Hi L. Anderson,

You are right. It's a different issue, which was explained when you posted previously. (-:

Please see the previous "comments".

Good Luck,
Ryan




offwhite marble color turning rust color.
by: Anonymous

I just installed 12x12 marble tiles in my bathroom. Within 12 hours of installation, some of the tiles started to darken and in the corners of the tile a rust color. I appears to be bleeding thru the edges. This completely changed the color my wife had carefully seleected by bring a dozen samples to the house. She is very upset but I'm sure as hell not going to take it out! I didn't realize how pourous marble is.

====Answer:

Actually marble isn't that porous. Comparatively speaking it is quite dense, however, if something like wet grout is pressed into the seams and onto a cut edge for twelve hours it can absorb.

This typically is only noticeable when using a grout color that is significantly darker than the marble color.

Sealing the edges is a common way to ensure grout doesn't absorb and mixing the grout as dry as possible too.

The rust color could also be from iron deposits in the marble (common in white marble) that has been oxidized from liquid absorbing into the marble and then evaporating through the surface carrying the rusty water with it.

This will likely be a difficult issue to remedy although you should be able to improve the situation following the stain-removal instructions in the Removing Granite & Marble Stains e-book.

Good Luck!




Remedy for Stone Turning Green
by: Anonymous

The reason why the stone is turning green is because most likely during installation, they used an accelerator to have the adhesives dry quicker, rather than using an air hose to dry it.

Once the stone starts to turn green, if something isn't done to fix it, it will just keep turning green to sometimes a teal/blue color.

I have a customer whose exotic level granite turned green, and it's been a nightmare to get it out.

I have read some articles about people using a combination of bleach and comet to make a paste like substance, but from working in the stone industry, and seeing what those type of chemicals can do to stone, I highly do not recommend it.

The best thing I know that does help the stone, is to mix 8-9 parts hydrogen peroxide and 1 part acetone then, apply to a white paper towel that doesn't have any colorful prints, and cover with taped plastic for 3-4hrs.

Once that's completed remove and wipe area with acetone several times. Depending on what kind of glue or polish they used the acetone may eat away at it; therefore, you may want to check on it periodically. I hope this helps!

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