Hey Eric,
Over the years I have had this happen to me on multiple occasions-always with peroxide or bleach as the stain removing component.
In some cases color enhancer has helped and or a good cleaning. At times I have also gotten rings on the edges of where I layed the poultice. It was like It pulled the stain and it was somehow forced out to edges and required additional poulticing.
In other cases I have tried honing and repolishing these areas with little success.Sometimes MB-20 or a crystalizer may help. It seems to be a crap shoot unfortunately and can cost time.
That means repeated visits that a client in most cases will not pay for.
Anyway-I don't know the actual reason these occurrences happen but I am pretty satisfied we aren't bleaching color out of the stone as a mineral has a particular color which will only change or intensify when wet or highly polished.
I have been back to a job recently on a juparana top that we removed grease stains and were stuck with a lighter mark. After several years the light spot was gone. Not sure if it was the UV light but thast what I gotta figure.
I think time will fix the issue but pretty hard to tell that to the american consumer after the problem has occurred. 
So now we tell customers about all these pitfalls that can happen when poulticing. 
On Sun, May 13, 2012 at 4:45 PM, Eric - DGG <eric@dirtygroutguys.com> wrote:
   Thanks Fred. I assume you mean the Enhancing Sealer? Or is there another product?
 
 
Eric Lewis, Technical Mgr
DirtyGroutGuys.com
West Chester, PA 19380

On Fri, May 11, 2012 at 8:09 AM, Fred Hueston <fhueston@gmail.com> wrote:
Its possible the countertop was enhanced...If thats the case then you may need to apply a color enhancer. 

On Fri, May 11, 2012 at 7:13 AM, Eric - DGG <eric@dirtygroutguys.com> wrote:
   Granite countertop next to sink, along open seam. Customer asks if removal of old stain is possible. Customer cannot state the exact cause of stain. But as it's next to sink, one assumes organic or oil.
 
   So I poultice with DE & 40% hydrogen peroxide.
 
 
   After 48 hours, customer removed poultice and reports:
 
   "You are a miracle worker. Stain is gone. But now the spot is too clean for the surrounding area. I trust you can blend the effect."
 
   I'm only guessing that we pulled the color out of the stone? I haven't seen it personally yet, but am just looking for options. Other than poulticing the whole countertop. Is it possible to darken?
 
   It's not a complete disaster as customer was on the verge of replacement anyway, but was willing to give us a shot.
 
 
Eric Lewis, Technical Mgr
DirtyGroutGuys.com
West Chester, PA 19380

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Frederick M. Hueston PhD
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