Product KBC Grade A surface plate dyed granite??

[Eyecon]

Hi All,
I just picked up a Grade A 2 ledge 24x18x3 surface plate from KBC. The plate appears black all around but when I was installing the 3 point supports on the bottom I noticed that the plate is actually bright grey and appears to be dyed black. After cleaning for the first time with Windex, the rag was a bit darker as if some of the dye came out but the rag was clean after the second round of cleaning. What’s the deal with these surface plates, are really dyed black?

 

[Darren]

I have the same plate, same issue.

 

[Eyecon]

I have the same plate, same issue.

I did some measurements today using a 2um indicator and a gauge block(a sort of diy repeat-o-meter) and local flatness seems to be within the tolerance in the certificate which was .00015”, did you measure yours? I can’t find any definitive information online but dyed granite seems to be the norm for import plates. How long have you had yours?Are you having any problems with it?

 

[Darren]

I've had it about 2 years maybe. I checked it with a surface gauge and a known good precision straight edge with a light and couldn't see any deviation, so its good enough for my uses.