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-   -   Knife trick (http://www.firearmstalk.com/forums/f32/knife-trick-63660/)

kycol 05-01-2012 10:13 PM

Knife trick
 
I thought I would share this little trick, and see if anyone else has tried it. Almost 40 years ago I had a case knife that my brother in law gave me for Christmas. I could sharpen it razor shape put it in my pocket and in 2days it would need sharing. It just would not hold an edge. An older man told me to open the blade stick it Ina Irish potato and leave it over night. I did this and it turned the blade darker, but man it would sharpen so sharp it just jumped through anything and everything you put the blade to. And it held its edge seemed like forever. My best friend asked to use my knife and I warned him it was very sharp, he laid a piece of fuel line on the blade and pushed it with his thumb. It jumped through that line and half way through his thumb.

kytowboater 05-01-2012 10:44 PM

Sounds pretty awesome, wonder if you can use any ole potato.

UrbanNinja 05-01-2012 10:48 PM

Quote:

Originally Posted by kytowboater
Sounds pretty awesome, wonder if you can use any ole potato.

An Irish potato really isn't a potato at all. Its some kind of coconut snack.

mountainman13 05-01-2012 10:52 PM

It sounds like a chemical case hardening. Very interesting.

kycol 05-01-2012 10:55 PM

Quote:

Originally Posted by kytowboater
Sounds pretty awesome, wonder if you can use any ole potato.

Well to tell the truth I really don't know what kind of potato I used, it was what ever my Mom had at the time.

UrbanNinja 05-01-2012 10:58 PM

Quote:

Originally Posted by kycol

Well to tell the truth I really don't know what kind of potato I used, it was what ever my Mom had at the time.

So you assumed it was Irish just because it was a potato? Thats stereotyping man, shame on you. :D

But it is definitely cool.. what was causing your bade to dull so fast the first time?

mountainman13 05-01-2012 10:59 PM

High carbon steel I assume.

c3shooter 05-01-2012 11:05 PM

(Ahem) a side note to y'all folks from the Nawth-


In the south, the potato was traditionally referred to as an Irish Potato- to distinguish it from the Sweet Potato. One of the oldest heirloom varieties was the Irish Cobbler potato. In a like manner, green peas were English Peas, to distinguish them from black eyed peas (aka field peas or Crowder peas)

kycol 05-01-2012 11:39 PM

Quote:

Originally Posted by UrbanNinja

So you assumed it was Irish just because it was a potato? Thats stereotyping man, shame on you. :D

But it is definitely cool.. what was causing your bade to dull so fast the first time?

I really do not know but I guess the potato changed the properties of the steel.

canebrake 05-01-2012 11:48 PM

Not sure what this process does to help hold an edge but it does force a patina that protects a carbon steel knife blade.

The physics are as follows;
The starch in the potato oxidized. The Chlorogenic and Citric acid content in the potato worked on the starch resulting in various chemicals being produced including, but not limited to, Sodium Chlorate I and III and Hydrogen Peroxide. These chemicals then oxidize the steel in the knife in a similar process that is used in gun bluing.

Different types of potatoes will result in different patina. Different carbon content in the blade will also produce a different patina. No two will be alike.

This patina can also be forced by using horseradish mustard to to cause the chemical process. Using a flux brush to apply the mustard you can wind up with a patina that resembles Damascus steel.

Just don't forget to wash the knife after the patina level you want is achieved and then follow up with a good wax for even more protection. I find Renaissance Micro-Crystalline Wax Polish is about as good as it gets.

http://i695.photobucket.com/albums/v...sancewax-1.jpg

Have fun protecting your carbon knives!


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