Thread: How hot to retemper steel?

Questions always lead to more questions. kevint is hinting at the correct process.

I think you are asking about re-hardening the blade. If that's the case, you'll need at least 800C or 1500 F for a carbon steel and probably higher for stainless.

Re-hardening the blade can be done, but not in home build shop equipment and even then, with a finished-down-to-sharp-razor-blade there is a strong possibility of creating a newly hardened blade with a wavy potato chip edge.

I still need to know more about this blade. Where in MN? Send me a PM please.

You will need a forge and heat treating furnace/oven; it can be done with a torch but the results won't be as consistent as the two former. You could always send it over to a bladesmith but he will still guess work... to know exactly what kind of steel used in the razor you'd need access to a laboratory and a good chunk of that steel or there's always the grinding sparkles' test but I don't think you wanna do that! :P


To answer the question... the temperature should be just above non-magnetic range, most probably around 1400-1500F. But the razor WILL warp and be unusable, no questions about it. I'd just continue to use it like it is... does it shave well still?

Else, in the event that you get a forge, you could still use it to make some pattern welded blades.

Here's a good link about temp ranges:

[ABANA] Tempil Guide

It is not possible, if you dont have a wedge. With a halfhollow or hollow razor the result will look like this:


This razor I grounded to thin before the hardening Before the hardening you need at min. 0,5 mm thickness at the edge.

May I suggest that before you go the heat treating/tempering route that you should first verify that the blade has lost its temper ( it is to soft). Just hone up the blade and see if it will hold an edge thru a number of shaves. One of the indicators of softness that you can check for is microchipping on the edge while honing. If the temper has been lost then( steel is soft) it will not be strong enough to hold an edge when the steel is very fine/thin, i.e. 8000 grit.

Mike Blue is a very good and competent person to talk to regarding heat treating/tempering of steel.

Hope this helps,