Try the RSR 2000 first. Of course it will confirm what you already know which is that the spots are rust. It may reduce the rust some too, that is what it is for.
Easiest first step to take. Evaluate and then go from there.

Sent from Bob Murrell's iPhone
M3 Technologies, Inc.
865-607-0957
Office 800-342-4533
www.go2m3.com

> On Nov 9, 2018, at 3:56 PM, Brian Borgen <brianb@atlanticstoneandtilecare.com> wrote:
>
> Hi all, we encountered this situation a few days ago in a shower and
> our theory is that the spots are rust stains caused by nails below. We
> were looking for any helpful advice or confirmation that we can or
> cannot do anything to help with this.
>
> Thank you!
>
> --
> Brian Borgen
> Project Manager
> 843-539-8207
> Atlantic Stone and Tile Care
>
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