... My only test options are file,etch,edge flex and cut so improvements need to be fair to be noticable but they are noticable.I'll know more when I start cuttin'. [sure could use some of Kevin's equipment,IF I knew how to use it!!]
My equipment is not necessary for reasonable people who do not have my obsessive hang-ups. You can get a lot out of very simple testing tools if you know how to use them, but more importantly understand what it is they can measure and what their limitations are. Also, of course, be certain what it is that you are measuring even means anything for a knife.
Files are great as they test the steel in ways that hard objects will in use, however they cannot detect certain things. They can tell you that the OVERALL hardness is greater than a file but they cannot indicate grain size, in fact larger grain will actually obtain higher hardness with less effort. Files can be fooled very easily by fine pearlite for much the same reason they can be fooled by carbides. Imagine the hardened steel as a pile of long broken glass shards on the microscopic level, now fill in the spaces between the glass with well packed sand and in another pile fill the spaces with concrete. Rubbing over the top of either pile will hit the glass and give the impression of skating on hardened steel, but if you now take a pointed steel posts and stab it down into the pile one will give and the other will just bounce the pole. This is the difference from files and hardness testers with penetrators. Also both piles will tear up anything soft dragged over it giving the impression of good cutting ability for both but when something hard is brought against them the sand will not be great support and the glass shard will tend to snap off and the pile will deform. This is a good analogy for blade that has fine pearlite or rely to heavily on carbides in a soft matrix.
macroscopic preparation and etching can only show you overall transitions of differing microstructures in the steel. For example you can get an idea of where the martensite peters out and the pearlite picks up. But contrary to popular belief it really can't tell you much about grain size at all. If you grains are visible to on the blade surface to the naked eye, they are WAY too big- as in throw the blade away. In order to use it for these more advanced methods of analysis, one needs to properly prepare a cross sectioned piece with extensive polishing and etch it in an appropriate etchant (I like 5% nital) and put it under a good microscope. It is worth mentioning that ferric chloride is all but useless for general metallography. Dipping a blade in HCL or FeCl will increase the contrast of the hardening line and allow you to more easily see how far up form the edge you hardened, which can be helpful, but that is about the extent of it.
Many use edge flexing, or overall flexing for that matter, but since it is so much more dependent on geometry than heat treating I just don't rely on it that much. I have a brass rod test, but it is a ½” rod and doesn't involve any slow flexing. I am into impact, and have never needed to slowly flex them over something, so I bring my sharpened edges into rapid contact with things that push the limits.
Cutting things is great! But cut a wide variety of things not just a few mediums that will make your knives shine under very specific circumstances, if it is to be a general use knife. If your customer wants the ultimate skinner, and will only ever use it for that, then you could specialize in just that area of cutting and make it really shine.
By far the toughest test one could subject a knife to, in my opinion, is give it to your wife or mother and allow them to use it for 1 month in the kitchen, I believe that environment goes beyond abuse and into the all out torture of knives.
