Blue Stuff on Tempered Blades

S

Stoneface

Joined
Jun 7, 2014
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5
Pulling my latest batch out of tempering I noticed a Peacock Blue deposit on the edge of my blades.. it doesn't readily come off either.

This is NOT heat/tempering coloring of steel. It is a deposit mostly on the edge. It is (or was) 1095 carbon steel and yes I likely over heated the blades prior to quenching. (new propane gas forge)

I think it is likely the remains of some additive to the steel but I have no clue what it might be.. :confused:

Has anyone else seen this? Know what it is?

Thanks!
 
How thin is your edge?

How high were you tempering? How long?

What makes you absolutely sure it is not tempering colors on the thinner edge?
 
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My edge is a little thicker than I normally treat..

My temp was likely a little higher than normal. I don't use an instrument so can't say exactly how hot, but I have quenched hotter blades. I don't soak long at quench since I do that in an intermediate step.

I looked at it through a jeweler's loop and it is definitely sitting on top.. not a temper-like coloring, but more a deposit.

I've been quenching steel this way (other than changing to propane forge) since I was 8 yrs old, but I've never seen this before.. even when it was so hot to damage the steel. I've only done a hundred or so 1095.. but still...

something to do with propane???

THANKS!
-B
 
Well now Im intrigued ,can you post a pic and/or give a detailed description on your HT process?

Could it maybe be forge scale? What are you quenchin in?

Someone with a lot more experience should be along shortly.
 
The rainbow of colors...including blue, that form on a blade in temper are almost always just surface oxides and colors formed by oils, soaps, and other things in and on the blade surface. Pay them no mind unless the oven is suspected of going to 500-600F. The color that is most normal when the blades go in clean is a gold/bronze color.
 
sorry folks I tried several times to get a picture to show what I was talking about.. failed. It just would not show up on phonecam.

BUT.. it IS some kind of oxidation and didn't come out of the steel (as I had feared)..

most likely it did come from the veg-oil as there weren't any other possible contaminates.. I've probably had this before, but I always use borax in the old forge and now that I'm using the cleaner propane I can just see it now..

HOWEVER.. It makes me wonder now what's in our vegetable oil! :eek:

Thanks folks!
 
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