Mike,
Because sandstone is so coarse, any of your abrasives will wear at faster than normal rates.
There are many variables like will you be doing this wet or dry? Single disc or planetary machine? I am assuming the sandstone is already honed?
If it is honed and you intend on an initial coarse grind anyway (maybe some lippage too?), I would recommend a metal-bond diamond to start with as they should cut much faster and also last much longer. Depending on the thickness of the coating, maybe a 50g or 70g might work. Then go to the desired level of hone with resins and color enhance(if desired).
If you can, do some chemical stripping first to alleviate gumming up of the diamonds and floor.
Just keep in mind that all of your abrasives will wear faster than normal.
Do a test to confirm procedure and results.
Good luck,

Sent from Bob Murrell's iPhone
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> On May 8, 2015, at 4:48 PM, Mike Marsoun <nulifesc@bigpond.com> wrote:
>
> I have a customer who wants his Indian sandstone (Himalayan) ground. Someone put in a topical that is failing ant it has to come off, probably a urethane. Does anyone know of a good hard bound diamond for this? I usually use Frankfurt stones but this is indoors and they are a mess to work with. Thanks.
>
> Sent from my iPhone
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