We brought a pyrometer out to the lake with us for one of the brutally hot days in July-August. The light gray was 120 degrees, the silver billet aluminum plates were 135 and the red was 170. Dark orange was 140+ depending on where you looked in the blend. White was right around 120.
It makes a huge difference. You can sit on white, you can't sit on red or brown.
I'm very surprised there wasn't a larger gap in temperatures between colors. I would've thought silver/chrome billet plates would get up to 200+ degrees or there abouts. If you ever want to try it again, use a quick read cooking thermometer like what you'd use for a BBQ. The probe only reads at the tip, and they are deadly accurate.
RD