Glad y'all like them. Thanks so much.
Leozinho: Here are my thoughts on 1095, which should address all of your questions. This is a little verbose, so please bear with me.
When I was first starting out, I wanted a steel that I could easily heat treat myself. I felt that was an important skill to learn to do properly as a maker, and I also didn't want to give up control of that aspect of the process. With the technology I had at my disposal at the time, this limited my selection to oil hardening steels such as 01, 5160, and my personal favorite, 1095. I stuck with 1095 for a number of reasons:
1) It's a proven steel. Been around for a loooong time. Lots of notable makers who have been at this much longer than I have used it, and are still using it.
2) It's a simple steel. Not a lot of alloying elements, which appeals to me aesthetically.
3) It's a living steel, i.e., it readily develops a patina with use. Patinas are cool.
4) Visible temper lines/hamon. VERY cool.
5) With proper heat treat, it produces knives that are very tough, with good edge retention, which are still easy for users to sharpen in the field.
6) If you match the hardness to the tool, you can build pretty much anything out of it. I've done swords, hammers, axes, folders, big knives, small knives, you name it, all out of 1095.
7) Because it's so versatile, I don't have to stock 15 different steels. This makes life a whole lot easier. If it's in the shop and it's not marked, I know it's 1095.
8) I just plain love the stuff!
I would say absolutely, a differential heat treat helps make a tougher knife (insofar as oil and water hardening steels are concerned). Knives are a balance of hardness vs toughness, where hardness = brittleness, and toughness = ductility and lack of edge retention. With a differential heat treat, you get a nice hard edge, and a softer, tougher springier spine. Normally I'll just do an edge quench to achieve this, but I have selectively torch hardened blades, and also used clay coating. Wrangling a hot piece of steel and oxy/acetylene torch at the same time is always an adventure.
And then of course, you temper it after hardening. After that, some guys will torch draw the spine of the knife. Some guys just stick with the tempering cycles. I've done both, and not noticed an appreciable difference between the two insofar as toughness or performance is concerned. So I just stick with my tempering cycles.
On those two folders: The first knife is blued. The second knife was taken to final finish, heat treated, and then hit with a wire wheel. I called that a Gunmetal finish. Now I just heat treat and finish everything as normal and then blue as needed. I can get pretty much the same effect as the Gunmetal with just a regular Oxpho blue.
The negatives of 1095? You can't safely get it as hard as some stainless steels and not suffer from chipping or breakage. Also not very stain resistant. This isn't so much of a problem with modern oils and rust inhibitors. And as one of my friends is fond of saying, the samurai did just fine with their swords, and they lived on an island in the Pacific. And if rust is really going to be a big concern for a customer, there are all kinds of wonderful coatings out there as well.
I'd be happy to post up pics of a few of my personal knives that I've used hard (and which I'm not ashamed of), if you'd like to see how 1095 holds up over time.
None of this is to bag on any of the stainless steels out there. In fact, I'm in the process of getting an in-house midtech/production project up and running, and those knives are going to be stainless. CPM S35VN, to be precise. They'll also be V-ground vs my customs, which are only available left or right hand chisel ground. This way I've got something for everybody - whether you like stainless, or not, or chisel grinds or not, or you're willing to wait or you want/need something right now, I got you.
