Hi. I'm new here but was reading some of the honing threads and noticed a fair number of questions about JNats, how they're used and how they're different from other sharpening media. Maybe this will help? I've never honed a razor. In fact, I've never even used a straight razor (just a matter of time I'm sure), but I've spent the last several years learning how to sharpen higher end chefs knives. I've grown particularly fond of using JNats and wrote the following essay in response to a user's question on a knife forum I frequent. Hopefully it will provide some value here as well. Background: This discusses the use of synthetic stones, diamond plates instead of stones, polishing compounds like CBN and JNats for sharpening. My experience is sharpening high hardness steels (largely Japanese heat treatments). A question was asked by a friend of mine why not just sharpen your edge using diamond plates and JNat mud? There was also a question about why bother with (water soluble only please) compounds on JNats. I tried to answer starting with some comments on what happens in general when you sharpen steel, what's different about synthetics and JNats, and in the end I try to make it at least somewhat simple to understand --- even if the notation gets a little funky in the middle. What exactly happens when you're sharpening? Why bother with compounds? 1. Imagine your steel is made up of only two molecules. Extremely hard and relatively speaking soft. Further, imagine these molecules cluster in chunks. Finally imagine you have a single sharpening platform i.e, synthetic stone or plate . It is harder than the soft molecules but softer than the hard molecules. While sharpening the stone/plate will abrade the softer molecule cluster (sharpening it) but as the softer material is removed the harder material does not abrade. As the softer material is removed the harder material will either remain - leaving a less polished edge - or fall out - leaving let's call them craters in the edge. Kind of like a chocolate chip cookie with the dough as the softer material and the chocolate chips as the harder material. Using just my stone in the example above you'll sharpen the dough but the chocolate chips will get chunkier and chunkier and eventually fall out. Adding a compound -- harder than the chocolate chips -- would allow you to sharpen the harder molecules along with the softer molecules leaving a more refined edge. What are the differences between synthetics and JNats? Why bother with a compound on them? 2. Very loosely speaking JNats are "analog" while synthetics are "digital". When you're using a synthetic relatively speaking you're always sharpening at X grit. Add a compound to a synthetic X grit from the stone and Y grit from the compound. Nice. Simple. Sort of like two tuning forks with just two notes. It works. You know exactly what you're going to get. It's always the same. You get it immediately and it never varies. JNats are wonderfully more irregular than that. A whole spectrum of grits waiting to be released. If a JNat's molecules were the alphabet with A being coarse and Z being fine. [Work with me here it's going to get a little funky with the notation] Sharpen a little bit and you get a range from A - E. Further, as you sharpen that range breaks down further and you can get A-E plus maybe O-S as the mud breaks down. Now... add a compound grit Z to your [(A-E) + (O-S)] slurry and something really cool happens. A. Your compound is going to accelerate the breakdown of the stone, so you're going to get your [(A-E) + (O-S)] slurry faster. B. You're adding a finer molecule to the mix so now you have a slurry of [(A-E) + (O-S) +Z]. C. Presumably your compound is harder than any of the molecules in the stone it's breaking down so you're going to further refine those (A-E) and (O-S) components and maybe now you've got and added (T-V) component. So stretch this exercise to it's logical breaking point (as if I haven't already) by adding a compound to a JNat you could end up with a nice smooth alphabetic progression of grits from A-Z. Going back to the tuning fork example above you start with maybe a tuba and a clarinet each playing a single note and by the time you're done you've got a full orchestra playing a chord. Why not just use JNat mud on a synthetic stone ] or diamond plate? 3. Finally, and this is the really amazing thing about sharpening with JNats and why I love using them so much - this breakdown of the components takes place over time. You get to pick how much you want the slurry to break down and how fine you want that finish to become. It gets finer and finer the longer you work it. Arguably in order to accomplish the same with a synthetic and a compound you'd need a full progression of stone and compound with infinitely minuscule increments between each. [Note: I did say arguably.] SUMMARY: So . Back to the question: Why not just use JNat mud and a compound? You can. But when you do what's happening is you're breaking the molecules in the mud down to ever finer particles. When you use a stone and the compound the stone refreshes itself so you're exposing coarser particles while simultaneously adding in the finer ones. Just using the mud is like a slide trombone moving up the scale in pitch. It gets finer and finer the more you progress. By using a JNat you get to apply the full force of the full orchestra. New coarser stuff gets added as new stone is abraded while at the same time the older particles get finer and finer. Hope this made some sense. I had fun writing it.
