What type of peroxide have you tried 
A high volume peroxide as a poultice may be the answer
Oxygen bleach may be effective as well found in products like oxi clean.
Have you tried any acids
Hydrochloric diluted would be a good test
Prosoco if you have access has some great products
Fast strip is a solvent cocktail that makes a hell of poultice.
I would try a hydrogen peroxide 40 percent or more volume poultice with talc.
It will take 4 plus days to do.


Sent from my iPhone

On Mar 31, 2015, at 3:05 AM, Stephen Webb <stephen@newlifemarblerestoration.com> wrote:

Thank you very much for your help. gonna try the heat next. It's chiseled finish easy to see it goes into the stone

On 3/30/2015 8:50 PM, Hector Castillo wrote:
Dry dry steam at 60 to 90 psi or end a heat gun see if the is a change.
Even doc fred granite  test kit for dying. 
Has to be natural  dye mold or man made stain. Have scratch  the top to see if it in the stone?
Hector 


Sent from my Verizon Wireless 4G LTE smartphone


-------- Original message --------
From: Stephen Webb <stephen@newlifemarblerestoration.com>
Date:03/30/2015 11:38 PM (GMT-08:00)
To: sccpartners@stoneandtilepros.simplelists.com
Subject: Re: Trying to figure out what this is

Yes I used D/2 biological which has worked great on other mold projects but no effect here.

On 3/30/2015 5:27 PM, Hector Castillo wrote:
Don't  they make  a spray  for that type of mold.   dd2. I think not sure
Hector 


Sent from my Verizon Wireless 4G LTE smartphone


-------- Original message --------
From: stuart rosen <mail@stoneshine.com>
Date:03/30/2015 7:58 PM (GMT-08:00)
To: sccpartners@stoneandtilepros.simplelists.com
Subject: Re: Trying to figure out what this is

I would guess it has to do with moisture-spent some years climbing on sandstone out west.
Moisture caused some types of discoloring but if I remember most discolorations were black and similar to what's on your stone.
Maybe it is lichen growth-interior or exterior?
Maybe you need a mildecide , fungicide, biocide product. 


 

On Mon, Mar 30, 2015 at 9:46 PM, <hectorcastillo@comcast.net> wrote:
is the black in the grout ?
Hector Castillo



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