heat blueing ??

[OconeeDan]

I have seen some very nice looking knives (mainly damascus) that had heat blued blades. Some colors ranged from blue to amber.

I think it occurs about the same temperature you would anneal at, so am I wrong in assuming the temper would be fine?

What is the best way to accomplish this, with a torch or heat treating oven?

Durable?

Thanks, Dan

[Jeremy]

Steel takes on a blue color at around 600F.  

I've seen a few blades where the maker used a torch along the spine to draw the temper back to a blue color and left it that way.  Ended up with a dark blue spine fading to a straw yellow at the edge.

The damascus I've seen blued has all been hot blued with the standard salts, which is somewhere under 300F... Karl or someone familiar with gunsmithing should chime in with the exact temperature.