Effect of burning knives...

TheKnifeDude

TheKnifeDude

Joined
Jan 13, 2005
Messages
282
I have a friend with a Spyderco Endura stainless handle knife. I've looked at it recently and the blade looked black and burned. I asked him about it and he said he burned it with his lighter to make the steal harder. I told him that it ruined the heat treat, and I left it at that. In reality how it is it going to effect the knife? Any advice apprecitated...
 
LOL! thats pretty funny.
If he heated it up to the point where it was too hot to touch with his bare hands, there is a chance he ruined the heat treat.
 
The easiest way to find out is to use the knife and see if he ruined the heat treat. :)

A bic lighter runs on butane, and butane can burn very hot. I think he'd be hard pressed to get anything more than the very tip of the knife hot enough with a lighter though.
 
Stainless handle is AUS-6 blade material. I doubt he ruined the heat treatment. Like other says, use it and see if it was ruined.
 
I'd say there's a good chance that the knife isn't actually burned at all, but just covered with soot. You could test that by washing it with soap and water. If it's just blackened with soot, it will come clean and you may be able to assume he didn't hurt it after all.

Notice that in all the above responses it's unanimous that he didn't do anything that could in any way be beneficial to the knife (ie, heat it to 1400F and quench).

Mike
 
TheKnifeDude said:
... how it is it going to effect the knife
Click to expand...

As you heat up the knife you pass the temperature it was tempered and the blade will start to soften, the hotter it gets the softer the blade will get. A normal bic lighter gets hot enough to significantly soften blade, however he could have coated it with carbon with actual little heating.

-Cliff
 
Mwahahahaaa, what an idiot :D .
Thinking he can do a heat treat with a lighter. Sure does show how much he knows about knives and steels.
 
Just tell him to put in the freezer part of his refrigerator for a couple of months and it will be just fine!
 
He wasn't an idiot, he was trying something he heard about, even if he did hear it wrong. :D This is a chance for him to learn more, and maybe get interested in knives seriously.

One question he didn't ask is, would making it harder do anything useful, or would it just make it more brittle?

I used to do something like that with a lighter, running the flame under my hand, and leaving streaks of carbon, leaving people thinking I had burned myself. A fluid lighter did it very well, a butane didn't deposit as much soot, and came close to burning me to get the same effect.
 
I once had a co-worker who did something similar, probably heard about "heat treating" but didn't research it fully. He stuck a Western Bowie into a campfire. The blade was permanently discolored after that. I don't know if he altered the steel's physical properties or not, but I do know he ruined the aesthetics.

-Bob
 
I think your friend should heed the advice:
"If it ain't broke, don't fix it!"
 
Some makers do use refrigeration as part of their quench, and based on the numbers a search turned up for bic lighters, it may be possible to actually harden a blade by that method.

-Cliff
 
I doubt that he got it hot enough for long enough to do serious damage using a lighter. Most lighters would get too hot to hold before that happened. There is a slight chance that he damaged the hardness of the thinnest part of the edge. If that is the case the blade will get dull unusually fast. If it was a serrated blade the tips of the serrations are the likeliest parts to be weakened. A thorough sharpening would probably fix any problem. If the edge is softened it would be easier to hone off the softened material than normal.
 
Hmmm thanks for all the advice. I went to his place again and tried very hard to clean the blackness off the blade with wet semi abrasive cloth. It did not come off... :barf:
 
If the finish damage doesn't come off easily it sounds like he didn't just use a cigarette lighter. He might have uses some dirty organic fuel so you might try to clean it with gasoline, lighter fluid, or paint thinner. If he used something with a blue gas flame like a propane torch or a kitchen stove or a barbeque he may really have damaged the knife heat treatment. If he really clobbered it you could bend the blade with your fingers without applying much pressure. If that's the case it isn't worth trying to fix.
 
I worked for a guy that used to do the same thing with chisels and other cutting tools. I believed what he was doing was right until recently when I started making knives and learning about steel properties. It takes a lot of work to "untemper" steel...tempering is even more challenging and a lighter won't do it :thumbdn:
 
I tried this out of curiousity with a cheap "surgical" stainless blade. It is very easy to get the steel to turn a hint of yellow, but you have to leave it exposed to the flame a lot longer than necessary to just blacken it. Trying to really soften it by inducing a heavy burn with a blue/black color is next to impossible. Even after leaving the very tip in the flame for a full minute could not achieve anything beyond a faint yellow. Based on this I would think it is likely he didn't do much of anything to the blade.

-Cliff
 
You must log in or register to reply here.
Back
Top