Burned on a blade

Fatstrat

Well-Known Member
I'm not really a knife maker as much as a knife projecter. I buy old used knives or blade of good quality but poor condition, and use the the old blades to make a "new" knife. Sometimes just "rehandle" them. Or sometimes regrind/reshape the blade depending on condition.
So I buy a large Marbles brand bowie blade on Ebay. Pics show a pitted blade. But when it arrived I am convinced that the blade has been in a fire. And possibly if not probably has lost it's temper. While attempting to clean it up, I notice that the blade edge develops thin "flashing" that I've never experienced on any other blade.
So I'm wonder if there is a way to heat treat it at home. I don't own a forge to heat it up. But I do own an Acetylene torch. Does it matter how you heat it up?
 

Brad Lilly

Moderator and Awards Boss
Could the "flashing" be a wire edge? Have you got any brass rod? I like to sharpen a knife then do the brass rod test, Wane Goddard wrote a better description then me
The Brass Rod Test (as it appeared in BLADE Magazine) by Wayne Goddard

The brass rod test was demonstrated to me in 1959 by an old blacksmith who made knives in the 1930s. Here is my version of the brass rod test which is simple test of heat treating to help determine that a blade will hold up in normal use.

Clamp a 1/4-inch-diameter brass rod horizontally in a vise with the top half above the jaws. Or glue it to a piece of hardwood. Lay the knife edge on the brass rod at the same angle used for sharpening (about 15 degrees). Have a good light source behind the vise so that you can see the deflection caused by the rod on the edge. Apply enough pressure so that you can see the edge deflect. (When tested on a scale, the pressure works out to 35-40 lbs.) If the edge chips out with moderate pressure on the rod, the edge will most likely chip out in use. If the edge stays bent over in the deflected area, it will bend in use and be too soft to hold an edge. The edge of a superior blade will deflect on the rod and spring back straight.

The test is intended for knives in the hunting knife class. Thin filet knives or thick camp knives will not respond to the test in the same way. The blade that is too hard will chip out in normal use, too soft and the edge will bend. The brass rod test can quickly determine if the blade has a good balance of flexible strength and hardness sufficient to hold an edge.

The brass rod test as I present it is not intended to replace a hardness test to determine that a blade was fully hardened. It only applies to blades that have been tempered. I have worked out my version using it on blades made of alloy and carbon steel types that backyard heat treating methods are adequate for. The brass rod test is only a comparison test to determine what is in my opinion a hardness that will hold up in normal use. I started using is about thirty years ago and still think it is the best non field-use test I've found for testing the suitability of a blade steel and heat treatment for a working knife.
 
Top