Is there any one here who has the answer : what are this curious "WW" marks on the blade of numerous Busse, SRKW and SY knives? Thanks!

I'd guess the "coating" has been removed and that is either from production or made that way to "hold" the coating better.

satin, double-cut blades never have that (it's in the finishing and why they cost more <img src="/ubbthreads/images/graemlins/wink.gif" alt="" /> )

Yep, That's a CE Jack Hammer, I have one, and it has very similar marks, which are on almost all of the CE (Competition Edge) models I've seen. They don't bother me and I expect to see them on any CE blade, they're meant to be users. <img src="/ubbthreads/images/graemlins/wink.gif" alt="" /> <img src="/ubbthreads/images/graemlins/thumbup.gif" alt="" />

Looks like some machine marks... I have the same kind of multiples "w" marks on my CG Sarsquatches, CG HeavyHeart, CG Batac and Swamprat Ratweiler :

You will find those marks on most all INFI Busse's that are not doublecut or satin finished. The coating normally hides it.

Given the consistency of the marks across different blades, I expect it has something to do with QC after heat treat. :thumbup

It is my best guess that the "W" or zigzag marks are hardness test marks.

The various marks have been discussed quite a few times, but I have never seen where Jerry or Dan have ever commented or confirmed the cause of the marks. So, Speculation appears to be all we have.

From what I can find, certain hardness testing equipment can apparently be programmed to test in various patterns - including "Zigzag" patterns and similar. I "assume" there are benefits in testing in a "Pattern" vs. the MUCH more common method of hardness testing with a "Single" dent.
I have found "information" and descriptions of testing equipment capabilities to support certain Hardness testing machines being capable of such patterns.

However, I have searched and I cannot find ANY other "picture" examples of zigzag hardness testing patterns on steel on the web to compare. I would love some help on finding such pictures.

Hardness can be tested via a few different methods, but generally involves indenting the steel with either a tungsten carbide ball or diamond. I think most of the knife industry and industries using similar types of steel seem to be using tungsten carbide balls. The measurement of the indentions confirms a hardness reading.

In theory, testing in a wave pattern should assure better consistancy of the testing.

Puma knives are somewhat known for their "Hardness Mark" on the ricasso or flat grind areas of many of their blades. Puma obviously only makes "ONE" single indention measurement per blades. Puma generally even puts a sticker on the blade pointing out the hardness mark.

MOST knife companies and similar makers and fabricators of steel who do hardness testing seem to test with a "single" dent method. I assume these singled dent testers are MUCH cheaper to purchase and own.

If these marks are truly hardness testing, Busse apparently tests in a zigzag / "W" pattern. - Which should be a bit of a credit for more extensive hardness testing than most of the industry.

Having stripped many Busse knives, I have seen these marks at random locations on the various parts of the knives.

I have never seen the marks on the primary grinds, so "apparently" Busse, cuts blanks (either laser or water-jet most likely), heat-treats flat bar stock, tests hardness and defects, primary grinds and then either coats the blades or flat/surface grinds the various satin/LE blades. Then handles. Sharpening is generally last for most makers.

My guess is the dimples and stretch marks are effects from heat-treatment (?????).


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Sorry Bruce, that is nothing like what I believe Busse would use.

From the link, those appear to just be some sort of "Rasp Sticks" or something. They are calling them files for checking hardness. Those would seem too inacurate for what a good knife-maker needs. Even many small custom makers have better, more accurate and more capable tools.

I would be VERY confident Jerry would use a WAY more advanced method for checking hardness.

I think the "Indent" methods of testing are referred to as "Vickers" Hardness Testing tools or similar. The defice is pretty highly precision!

I don't have time to do extensive post or more research, but notice at the following link how the machine is capable of hardness testing in patterns such as: "zigzag" and other patterns of hardness testing via indents.

Vickers Hardness Test Equipment



I don't know "Exactly" what type of machine or brand Busse uses, but I would tend to believe the "Method" is most likely the "Vickers" Method or "Brinell" dent method rather than some scratch stick/rasp/file tool.

Further, a rasp/file would not leave the "Tracks" found on Busse blades. A rasp or file would cut a groove. The "Tracks" found on Busse blades would most likely be caused by "Multiple" indentions. It seems plausible to me that some variation of one of these multi-pattern Vicker's Automated hardness testers might likely be able to create the zigzag patterns on the Busse blades.

Vickers hardness Test

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I think KG makes a lot of sense.