At 12:48 PM 7/26/2013, neil n wrote:
>Ok. I see what you mean.    :)
>
>Link to image of steel temperature/colour chart:
>http://www.m4040.com/Knifemaking/PICTURES/Tutorial/GlowChart-sm.gif

More brown/purple than actual blue IIRC.  But it was a while
ago.  Also, those are optical colors produced by the increasing
thickness of a layer of oxide on a polished surface.  They're only
sort of accurate the first time around, I would think.  I've watched
them form on freshly polished copper (copper tubing bail around a
compass) on a boat over a space of 45 minutes or so.  Fascinating
though it was my labor being destroyed.

Your,
David