10 years ago, I wrote a pair of articles – What is a burr? part 1 and part 2. These were based on results from straight razor honing experiments, where the sharpening angle is typically 8 degrees per side. More recently, I have been studying burr formation, refinement and removal on knives, where the optimal […]
In 2018 I wrote an article about ceramic blades where I showed that the brittleness of the material (Yttria-Stabilized Zirconia – YSZ) makes it difficult to produce a refined, keen edge and that there is little value in doing so as it will microchip quickly with use. The appeal of ceramic knives is not their […]
The title is provocative, but these 7 statements are too often made without reservation. As with most things, the reality is nuanced and depends on multiple factors. My intent with this article to demonstrate that knife burrs can take a variety of forms and explain why the 7 statements are at best only sometimes true. Hopefully, this […]
In December 2022, I purchased one of the Spyderco Manix 2 sprint run knives in 15V steel produced with the heat treatment developed by Shawn Houston (Triple B Handmade knives) that produces an impressive Rockwell hardness of 65 HRC. CPM 15V steel from Crucible Industries (datasheet) is a high vanadium (14.5% by weight) wear resistant tool […]
I will describe four methods which lead to different outcomes for sharpening this S110V knife. Many other approaches exist, but there are a finite number of final outcomes for microstructure and geometry of the cutting edge. Beyond geometry, the amount of damage to the steel below the apex will also be determined by sharpening technique. […]
In part 1 of this article, I discussed some of the open questions about this class of steel. Here, in part 2, I show the issues arising when sharpening by various techniques. Sharpening by plated diamonds on a guided system (Wicked Edge). For the first sharpening, I used Wicked Edge diamond stones, 200, 400 and […]
This article is the third in the “carbides” series, following Carbides in Maxamet and Carbides in K390. I have split this post into 3 parts to improve readability. Part 1 includes the preamble and images of the blade after the factory edge was dulled with use. Part 2 shows the effects of several sharpening techniques […]
I’ve titled this article “carbides in K390” with the idea that it will be part of a series that aims to help understand the role of carbides in knife performance and sharpening. The first article in this series, Carbides in Maxamet, dispelled the myth that carbides are weakly bonded to the surrounding steel matrix. Of […]
A few months ago, a video was posted by Pete Colligan on his Cedric & Ada YouTube channel demonstrating the enhancement in edge retention of a knife sharpened by a novel technique, where one side was sharpened with a coarse diamond plate and the other side with a fine grit aluminum oxide hone. Gabe Kirkwood, […]
A discussion of blade sharpening for specific types of cutting requires an understanding of the slice cut vs the push cut. Cutting with a bladed tool can involve both motion perpendicular to the blade; pushing the blade through the material, and a slicing motion parallel to the blade. Occasionally the terms push and pull are […]
This is a quick update to my previous post about that “12k resin bonded diamond” stone. Apparently, I created some controversy that I would like to take a minute to discuss and clarify. Initially, I was very surprised to discover that “resin bonded diamond” doesn’t actually mean diamond abrasive suspended in polymer, but rather the […]
It’s been a while since I posted anything. I do have several partly written, but I just haven’t had the motivation to finish them. So I thought I’d just put up a quick one today. I bought this aluminum plate with a thin layer of green resin on the surface, which was claimed to contain […]
Carbides in steel are often compared to gravel in concrete. While there are some parallels, such an improving wear resistance, the analogy fails in the prediction that carbides can “pop out” of the matrix. We are all familiar with the surface voids produced in concrete when a stone from the mix falls out after beings […]
It has become a somewhat common practice to follow a “progression” of increasingly finer grit abrasives when sharpening a blade. In principle, this process is comparable to the procedure for metallographic polishing, which typically consists of three stages, coarse grinding, fine grinding and polishing. These steps are usually characterized by “the scratch pattern” for want […]
In Part 1 of this series, I showed that, contrary to myth, honing rods (including smooth honing steels) restore cutting efficacy by removing steel from the blade, not by "realigning the edge."
It is a common misconception that steeling does not remove metal, but simply "re-aligns the edge."
Ceramic kitchen knives are relatively inexpensive and are claimed to “stay sharp” longer than traditional steel knives. For this study, I purchased some “name brand” blades made by the Kyocera Japan, and some inexpensive “Gibson” brand knives imported from China by Bed Bath & Beyond, as well as a very inexpensive knife from my local […]
It is a common assumption that coarse hones (lower grit rating, larger grit dimension) remove metal faster than fine hones. However…. In the Swarf! article, it was observed that coarser hones remove larger pieces of metal. At the same time, we should expect that a finer hone will contain a higher density of abrasive particles. […]
The article It’s too big of a jump! showed that the scratches produced by a Shapton Pro 320 grit hone and a Shapton Glass 16k hone do not display a fifty-fold difference in depth or width, although the nominal grit size in those two hones differs by a factor of fifty. To further demonstrate this […]
The purpose of this article is to briefly demonstrate the difference between optical and electron microscopy of a knife blade. The difference between “sharp” and “dull” will be measured in microns. The difference between somewhat sharp and very sharp will be measured in fractions of a micron. To directly “see” these difference with a microscope […]
In part 1 of the series, it was shown that edge-trailing and edge-leading strokes on a hard, flat abrasive hone lead to entirely different processes for apex formation and refinement. The edge trailing (stropping) stroke allows a keener apex to form by avoiding the micro-chipping that occurs in edge-leading strokes. However, the edge-trailing stroke can […]
When I first became seriously interested in this topic about four years ago, consistently honing a straight razor to the level of keenness required for a close, comfortable shave challenged me. Having earned my living for the past 25 years solving problems like these, I began by searching for relevant scientific literature as well as […]
I decided to write this short addendum to “Does JNat slurry break down?” to address an ongoing misconception about the nature of the abrasive grit in Japanese finishing stones. Anyone who browses the internet on this topic is likely to find reference to the opinion that the abrasive in Japanese finishing stones (Toishi) consists of […]
In a recent post, Sharpening with the King 1k/6k combination stone, I showed one example of burr removal, folding the burr and removing it (at the sharpening angle). In this post, I demonstrate two other techniques for burr removal; stropping and high-angle-passes. As discussed in What is a burr? part 1 and What is a […]
This report illustrates a sharpening progression inspired by techniques demonstrated by knife maker Murray Carter in his straight razor honing video: This series of images is particularly effective in demonstrating the differences between edge leading and edge trailing strokes. A technique for burr removal is also illustrated. First, a comparison of edge-leading and edge-trailing sharpening […]