What would create a better result?
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From what I’m hearing, the lapping films and stropping don’t really work that well together. Lapping films give you more of a true V edge and very refined,in other words, very little tooth, and stropping gives more of a convex edge, all be it very slight, and depending on how it’s done will leave some tooth in the edge. I only have the 6 micron lapping film but do have a full arsenal of strops, 14/10-5/3.5-1/.5 balsa, same in the leather and the emulsions in leather 4/2, kangaroo 1/.5 microns. The 6 micron lapping film produces a very clean edge and I’m going to invest in more of the lapping films in the future. As far as the result goes that depends on what result you are looking for. I don’t try to put the same edge on every knife I sharpen because it’s my belief that knives serve different purposes and I “try” to put the edge on the knife for it’s intended use and the person using it.
That damn bug bit me too! LOL
Never say never. I don’t think there’s an incompatibility between film and strops, they just work differently. Film seems to leave a scratch pattern which is a straight function of the grit size. Strops have more of a burnishing effect. My guess is that the difference is that one has a hard backing and the other has a (relatively) soft backing. With the soft backing, grit particles embed themselves into the backing, thereby exposing small amounts of cutting edges. Rather than biting into the steel to produce scratches, the grit tends to rub against the surface of the steel. The contact point pressure that would produce a scratch drives the particles deeper into the backing.
If you’re a farmer, it’s similar to the difference between a plow and a cultivator. The plow blades are fixed and the cultivator teeth are spring-loaded. Even though the two may have the same tooth size, the effects are quite different. Does that make sense, or am I going a little off the wall in my old age.
If I’m right, this means that a strop works more like a waterstone, where a slurry of stone particles rolls around between the blade and the stone. Mark76, you know more about waterstones. Is this correct?
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“Better Results to do What?” What are you doing with your knives?
I find for my utility use, such as a kitchen knives, to cut and prep food to cook and eat, the stropped edge gives me that sharp clean sliding edge that easily cuts and slices my food. These knives I don’t sharpen to admire and show off how incredibly sharp they are by cutting and splitting hairs. These knife edges I find are more durable and lasting without the keen highly polished bevels that photograph so beautifully. I strive for small, close uniform scratch patterns in a direction to enhance the knife’s ability to grab and cut into food. (I follow the sharpening progression to 5000 or 8000 grit). The stropping for me then refines or smoothes a little bit of the toothines left from sharpening to help the edge slide down, in and through, what I’m cutting. I test these just sharpened kitchen knives for sharpness by cutting news paper. When not stropped the knife edge grabs and holds the paper and sort of sticks or holds then cuts then sticks or holds then cuts giving a little slowing resistance as I gently pull it down through the paper. The same sharpened edge after stropping almost effortlessly cuts and slides down through the paper with out grabbing and holding or sticking to the paper. You can here a wisp sound as it cuts the newspaper into ribbons. It won’t cut hairs.
I have tried to sharpen these same kitchen knives to a highly polished edge, using and stopping my progression at the 0.1 micron lapping films. I found the edge to be very sharp and shiny to begin with and very quick to loose that just sharpened feel. They just lack the longevity and durability of the edge.
Here is a picture with a USB Microscope of a brand new, hand forged, High-end, Japanese Chef’s knife, right out-of-the-box.
You can see how the knife maker sharpened it. This new knife was incredibly sharp and a pleasure to use. I have looked under the microscope and photographed the edge of the last five kitchen knives I purchased. So I would know how the new edge had been sharpened. They all share in common this same appearance in the bevels. I believe if these knives worked better with the shiny, highly polished, keen bevel, that is how the makers would have sharpen them.I have tried to put a highly polished keen edge on some of these Chef’s knives, that misadventure I will save for the Forum Post: “Sharpening Stainless Steel and Japanese High Speed Tool Steel”
Marc
(MarcH's Rack-Its)Never say never. I don’t think there’s an incompatibility between film and strops, they just work differently. Film seems to leave a scratch pattern which is a straight function of the grit size. Strops have more of a burnishing effect. My guess is that the difference is that one has a hard backing and the other has a (relatively) soft backing. With the soft backing, grit particles embed themselves into the backing, thereby exposing small amounts of cutting edges. Rather than biting into the steel to produce scratches, the grit tends to rub against the surface of the steel. The contact point pressure that would produce a scratch drives the particles deeper into the backing. If you’re a farmer, it’s similar to the difference between a plow and a cultivator. The plow blades are fixed and the cultivator teeth are spring-loaded. Even though the two may have the same tooth size, the effects are quite different. Does that make sense, or am I going a little off the wall in my old age.
If I’m right, this means that a strop works more like a waterstone, where a slurry of stone particles rolls around between the blade and the stone. Mark76, you know more about waterstones. Is this correct? Your right TC never say never. I don’t have the lapping experience so it is difficult to make an informed decision on them. I have heard from at least 8-10 different people that stropping after lapping tends to kill there edge. Again depends on what edge you are trying to achieve. Thanks
Also good stuff on that post Marc!
tcmeyer,
That does make great sense. I never thought of it like that. My goal is to eventually get a razor sharp, mirror polished edge. I know I will have to practice a lot to obtain the experience and technique and I am willing to put in the time, practice, and patience to get there. My grandfather used to farm and garden, so the analogy made perfect sense to me.
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From my extremely limited experience, stropping an 800 grit edge with the 4 / 2 diamond emulsions on leather at 2 degrees lower gave a dramatic improvement in how smoothly the knife cuts. Using those same strops on a 6 micron lapping film edge (different knife) seemed to dramatically decrease the slicing and push cutting ability on thin paper. This sharpness was restored by just a few passes with the 6 micron film. I think my stropping technique must be wrong or something because those results don’t make sense to me. I’ve tried both heavy pressure and light pressure on the strops with basically the same results. I hope to figure it out one of these days.
This is intriguing to say the least. Keep me informed with your findings and I’ll do the same. I have been told by some people that they do better stropping with more pressure or force than with light pressure applied to the bevel. I have been trying different angle adjustments. (less than 2 degrees, 1 degree and no decrease) before stropping but nothing conclusive yet.
Marc
Marc
(MarcH's Rack-Its)
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