odd heat marks on a case

A

archertl

Joined
Nov 3, 2013
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I picked this 3 dot texas jack up. Its in ok shape. My question is has anyone ever seen the odd mark on the tip of any case carbon steel slip joints. It is on both the pen and clip blade. It is obviously caused by heat. I wonder if at one point someone tryed to harden the point of the blade or if it was the result of negligent use. Was it common for people to harden the points on knives?

 
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archertl said:
I picked this 3 dot texas jack up. Its in ok shape. My question is has anyone ever seen the odd mark on the tip of any case carbon steel slip joints. It is on both the pen and clip blade. It is obviously caused by heat. I wonder if at one point someone tryed to harden the point of the blade or if it was the result of negligent use. Was it common for people to harden the points on knives?
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Only a guess on my part as it could be a heat mark from either a reprofile (minor) as it looks pretty full blade wise? Or if sharpened with a belt maybe the tip became to hot during the process?

I'm not aware of someone hardening the tip of their blade?

Regardless welcome to the Traditional forum:thumbup:
 
I wonder if it could be from someone "sanitizing" the blade with a flame before digging out a splinter or somesuch. I dunno...does a match or lighter get hot enough to change the color of the steel?

Frosty
 
Frostyfingers said:
I wonder if it could be from someone "sanitizing" the blade with a flame before digging out a splinter or somesuch. I dunno...does a match or lighter get hot enough to change the color of the steel?

Frosty
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Good scenario Frosty:thumbup: I've done such a thing years ago;)
 
Looks to me like it was heated up on the stove to cut/melt polypropylene cordage-eg paracord or the like. How do I arrive at this conclusion?
It looks just like the one I use for this task in the kitchen (not a nice old case or anything just a cheap kitchen slicer from Kmart or somewhere).
 
Interesting. does this heat from a stove or match damage the temper of the steel? I also have a blade with the very last part of the tip discoloured through heat.
 
Could be a chemical reaction from cutting open the cap on a liquid chemical. The Clip blade on this Kabar 1081 Medium Stockman was used (by me) to open the seal on a jug of antifreeze years ago - I watched the outside end of the steel turn blue from the liquid while it lay right beside the jug I had just opened. I never noticed what turned the end of the Spey blade blue - I just assume the carbon content of the steel in this knife lends itself to quick and easy discoloration (note all the pepper spots). The Sheepfoot blade is still the original color (looks dark in the photo, but that is shadow from the blade angle). The blue color has never worn off and hasn't seemed to hurt the edge holding quality of the blade either - I think the only change was the color. OH

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fatcorgi said:
Interesting. does this heat from a stove or match damage the temper of the steel? I also have a blade with the very last part of the tip discoloured through heat.
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Since high heat (glowing or nearly so) is the primary method for hardening & softening steel, it will certainly change the hardness if not re-treated. The tip is particularly vulnerable since heat applied to main part of the blade has adjacent material to dissipate through. Heat dissipates through steel much faster than air, so heat builds in the tip, and it gets hotter than the rest of blade. As an amateur knife grinder, I see this a lot when grinding near the tip. Aggressive polishing near the tip could also cause this damage.
 
Old Hunter said:
Could be a chemical reaction from cutting open the cap on a liquid chemical. The Clip blade on this Kabar 1081 Medium Stockman was used (by me) to open the seal on a jug of antifreeze years ago - I watched the outside end of the steel turn blue from the liquid while it lay right beside the jug I had just opened. I never noticed what turned the end of the Spey blade blue - I just assume the carbon content of the steel in this knife lends itself to quick and easy discoloration (note all the pepper spots). The Sheepfoot blade is still the original color (looks dark in the photo, but that is shadow from the blade angle). The blue color has never worn off and hasn't seemed to hurt the edge holding quality of the blade either - I think the only change was the color. OH
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I agree with OH. It is not obvious to me that the discoloration of the tip indicates that it must have been heated. There are other exposures which could have discolored the steel in such a manner.

And, in answer to the original question, I have never heard of someone preferentially hardening the tip of a pocket knife. Heating the tip in a regular flame would soften it, not harden it. You'd have to take it to 1000+°F to heat, then quench. Not a happening thing. And for certain sure, not common practice.
 
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