Jayne,

Hi. Good to hear from you.

I do not have any good safe off the top of my head answer.

Is it surface dirt that you are intending to remove? If it were a 
granite floor there are several techniques used w/ the two prevalent 
being diamond polishing (very fine diamonds) or the use of acidic 
cleaners. If you go to the Building Stone Institute their idea of stone 
restoration is exactly this practice of cleaning stone floors like in 
lobbies of large commercial buildings. They have had some very heated 
arguments over these two techniques. You can get this grinding equipment 
in hand-held sizes, you can also get hand-rub diamond blocks. Though I 
would be very hesitant to use any of it without a great deal of 
experiment and investigation on non-sensitive materials. This is the 
methodology by which the original polish on the granite was produced... 
going from coarse to super-fine mechanically applied abrasives. You may 
look to see if there is a stone fabricator near you that you can visit 
and learn from their techniques. I have worked on refinishing historic 
granite/marble floors before and can assure you that a whole lot of 
irreversible damage can be done in the first 2 minutes.

The only other approach that I am aware of would involve figuring out 
how to chemically break down the surface dirt... which is what you are 
doing with the ProSoCo materials on the other stone surfaces. If it is 
not working then you need to go to figure out what it is chemically that 
you are trying to remove on a molecular level and from there go with the 
chemistry.

][<en

Uhlir wrote:

>Hi All,
>
>I’ve been skulking around the perimeter of this listserv well over a year now and 
>recognize I’m past due introducing myself.
>
>I’m a project manager in Denver, currently working a corporate ebusiness contract, which 
>could not be a further throw from the wonderful world of stone.  Most other times, 
>however, I’m easily found in two of our historic cemeteries.
>
>Over the last few years, I’ve done monument conservation training with NCPTT, received 
>my cert from Jahn to use their restoration mortars and generally spend my time teaching 
>other volunteers stone assessment practices and cleaning, and doing small repairs. 
>
>We’ve had success with several products from Prosoco (Biowash & 2010) on stable but 
>soiled marble, limestone, and unpolished granite monuments.   However, I haven’t had 
>any success cleaning polished granite.  Most of the soiling is obvious black layering which 
>is likely carbon based deposits from the many industrial stacks and railroad/other vehicle 
>emissions so prevalent in the area.
>
>Does anyone have thoughts on how to safely clean these polished granite headstones and 
>monuments?
>
>Many thanks,
>Jayne Uhlir
>
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