Nemo: when you buy a knife you will be sooner or later, depending of many factors, confronted to a dull edge. Getting away from the factory edge is like leaving your parent’s home: it is uncharted territory for most of us. So should you waith for the knife to be dull or immediatly hit the stones to make it yours and why ?
JD: When I get a new knife I check the edge to see what condition it is in. I pinch it between my fingers to see how thick it how thick the blade is just behind the edge. And just look at the edge see if the edge bevel is even. Some times you can see unevenness close to the ricasso. That will take some extra attention and work on the hone to get right. I use light to see if it reflects of the edge, if it does there is a dull spot. Then I check for a burr with my thump nail.
If there is a burr I take a hone, usually the diamond side of the Fallkniven DC4, and remove it. Now I take a receipt of shopping, they are usually thin and consistent, and try push cutting and slicing it. If it cuts the paper cleanly and easily it is good enough to start using. If not, then I will sharpen it first. Depending on edge thickness, edge angle, and steel and what I feel like (knives are a hobby for me!) I will pic a hone and start sharpening.
Nemo: knowing sharpening is your hobby is a knife easy to get dull a dream for you ? Or do you prefer your sharp edge to remain sharp for a long time ?
Would you enjoy D2 more than Elmax ?
JD: a knife is for cutting and it cut better when sharp. I prefer a sharp knife! 🙂 It needs to cut what I need to cut with ease otherwise it is back to the hone it goes! I also like a knife that when it looses sharpness is easy to get sharp again. So I have no need for high wear resistant steels. But if they are thin at the edge and I like the rest of the knife it would not hold me back either.
If they are both well heat treated and kept cool in production and sharpening there after, both D2 and Elmax would work fine form me. I do not think I could tell them apart in use or sharpening. I am not much of a steel junky, though I like reading about the science of how steel works in knives. (I highly recommend the following books: (in German) Roman Landes: Messerklingen und Stahl and (in English): John D. Verhoeven: Metallurgy of Steel for Bladesmiths!) For me blade geometry and sharpness make a relevant difference. I can tell a thick knife from a thin knife and a dull one from a sharp one far better than the edge retention one steel from another.
The biggest differences in steel that I notice are, first, how they sharpen, how easy or hard it is to remove steel, and second, how stainless they are. The last bit mostly when cutting fruit.
Nemo: Sharpening wise: what would be the main difference between hollow ground knives and flat grind ?
JD: If they are the same thickness behind the edge the hollow ground blade wil take less effort to make the blade even thinner behind the edge, and take less effort to keep the blade thin behind the edge. Hollow ground knives can be laid flat on a hone to make and keep them thin. I have done this with a few knives. One of them a Spyderco Salt1. Now it is almost a single bevel grind (‘scandi’) and much thinner behind the edge. This has made it cut a lot better.
The same can be done with a knife with flat bevels, it just takes more work. When you use and sharpen a knife for a while the edge gets closer to the back of the blade and gets thicker. When it gets thicker it cut worse. To make it cut well again the area behind the edge needs to be thinned out. As a hollow ground knife has less steel behind the edge it takes less work to keep it thin behind the edge.
On flat ground you often need to remove the scratches after …
My first Zero Tolerance was 
As you can notice, it’s easy to pinch your finger between the stud and the handle when opening the blade. So really, it’s a true flipper made to be open in that way. And here the experience is wonderful. The smooth KVT ball-bearing opening system. A washer with caged ball bearings surrounds the pivot and makes opening the knife nearly frictionless. Only the detent ball brings some minor friction actually. But it’s really minimal. The knife opens every time. The balance is perfect, just behind the pivot. So the blade is alive in my hand. 
What you noticed first when handling the ZT0562CF is her smooth Carbon Fibers scale and butter like action. It’s 156 grams heavy compared to my Military 120 grams (titanium clip)… You fee the heft. And that’s exactly what I wanted. The corners are chanfered and there is no hot spots even the clip is not felt in hammer grip. I love the details on the blade: the stonewashed flat side and the satine grind. 
It offers alsmot the same working edge. It carries tip up and it’s not as fast to draw as the Millie even with its titanium deep carry clip. The blade is made of CPM 20CV but it was first offered in 
You can notice the different surface works on that picture. But as far as the blade was beautiful I felt the edge was thick compared to what I’m used too.
I have started with the diamonds of the Fallkniven DC4. It was not easy as I felt the thumb studs was going in the way. eventually I was able to de-shoulder the edge and even to scratch the blade. That “Hinderer flat-ground “slicer” grind” that should provide both slicing efficiency and a tough point was not easy to get at first. 
Against the scratches I has used a P1000 Sandpaper and they were erased. No big deal. They have disappeared just but doing an 90° motion. I have treated all the blade for good measure. 
Then came the work on the brown stone, the brown ceramic and the white ceramic. My edge was slowly going convexed. My favorite one for stropping. Soon CPM-20CV was back to razor. I was amazed by the way the steel react under the ceramic. It was much easier than I thought. I had the same excellent experience with my 
True convex razor as the hairs were jumping on the blade.
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