Chris
For what its worth I have seen  hundred year old white  marble in bathrooms and or wet areas with no sign of oxidation.
I have also seen quite a few new installations where the marble oxidized in specific places where moisture found its way into the stone.
Seems to be pretty random when it happens .
Sometimes we have been successful while other times we had no joy. Then there were the times we removed the rust stain only to have it come back.
The iron out can be pretty effective at times and produce good results. If you read the MSDS sheet you will see there is a lot of chemistry going on.
So be careful and do some testing so you can know what type results you can produce.
Over the past few years I walk from these type jobs unless they want to pay me for my time with no guaranteed result.
I still get them from time to time but I make sure in writing we are all on the same page. A 50% deposit gets me onto the jobsite with progressive payments that ensure a small final payment
I think the best solution in some of these cases is a replacement.




  


On Fri, Jun 27, 2014 at 7:45 PM, Chris <csantospago@gmail.com> wrote:
Great information on the white marble Stuart. I appreciate it. There are several units in this building that have this issue. It's all new construction and it seems like just the bathrooms with the windows this has occurred. I believe the sun heated up the tile and the hot Tile sucked the moisture from the cement underneath. It is a very slight yellowish-brown that has surfaced. Some spots it is through out the whole tile and some spots is just around the grout line.

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On Jun 27, 2014, at 5:24 PM, stuart rosen <mail@stoneshine.com> wrote:

Yes.
The darkening is from the poulticing.
It will go away as it dries.
Prior to deciding on which poultice to use its best to try and determine what has gotten in to the stone to stain it.
In the case of white marble which can contain ferrous minerals, stains that are yellow in nature can be a result of oxidation.
The stain can be light yellow to deep brown in color.
Oxidation can be tough to remove-iron out (found at hardware and boxstores) can work well sometimes. The problem is the oxidation will return if there is moisture in the equation.
If the client has extra tiles an option to replace them can be considered but if its a spot that is prone to intrusion of moisture then a change out may rust as well.




On Fri, Jun 27, 2014 at 4:28 PM, Chris <csantospago@gmail.com> wrote:
I applied a poultice of DE and mineral spirits to a Carrara honed floor. It was some yellowish stains that I was trying to remove and 24 hours after applying the poultice I removed the plastic and it looks as though the poultice has darkens the stone around the area. I believe this will dry up and disappear but I just want to know if anybody has some feedback on this.
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Regards,
Stu Rosen
201-446-1200
"EVERYTHING MATTERS"


 
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Regards,
Stu Rosen
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www.stoneshine.com
www.mbstonecare.com
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"EVERYTHING MATTERS"