I received mine yesterday, so thought I would take the opportunity to talk about my initial impressions with this steel which Robin enjoys so much...
Firstly, the edge was sharp out of the box, but the tip was broken off (There was a chamfer on the side of the steel bar, making the tip too thin to be stable.), giving me the opportunity to sharpen it.
Unlike Benuser, I decided to go the full crazy and sharpen it as a true single bevel, so I spent a total of 3-hours on an Atoma 140 flattening the back, grinding the spine to remove the chamfer and stabilize the tip, and clean up the primary bevel. I'm used to this sort of prep work with western chisels, so knew what to expect... Note: for those of you who also purchased a kogatana from Robin's first 'production run', and do not wish to go to this effort, I would sharpen this knife as a 99/1 double bevel at a very acute angle... Afterwards, the sharpening commenced, and - in the spirit of a true scientific test - I gave it a try on every type of stone I own. After the grind was perfected on the plate, the actual sharpening went lightning fast.
I can categorically state, that Robin's Bohler-Uddeholm UHB20C is
the easiest steel I have ever had the pleasure of sharpening, and took an absurdly sharp edge. The closest comparison I can make is with Shirogami #2 (In my case, a Hiroshi Kato made Masakage Yuki @ ~62hrc.), but this is even easier to grind, feels better on the stones (Almost buttery), and gets a little bit sharper. Based upon abrasion feel, and the level of refinement this accepts, I would say that Robin's really nailed the HT, resulting in a
very fine grain (Finer than just about anything else I own.). Like Shirogami #2, it takes a more refined, rather than 'toothy' edge like some of the more heavily alloyed carbons at a given grit.
A couple of things struck me whilst sharpening it... Firstly, the way it responded to even the most basic of sharpening equipment. Normally, something like Arkansas stones don't do a whole lot on a steel this hard (~63hrc quoted... Is this based upon rockwell testing, or HT charts, Robin?), but I decided to try an Arky progression for sherry and giggles and was quite surprised at their ability to both shape and sharpen it to a hair-whittling edge. It also responded to stropping on bare leather more dramatically than most steels, taking on noticeable refinement from this process... In the course of sharpening, I also tried it with finer diamond plates, diamond pasted strops (Monocrystaline), synthetic stones of various constructions and grits, Belgian Coticules and BBW's, a couple of different J-Nats, and some more obscure slates/sandstones (Like the La Pyrenees). The kogatana responded well to every single media I used with pleasurable feedback, and on naturals in the 'razor pre-finisher' level and above, takes an edge that easily tree-tops hair. One of the more interesting experiences were with the diamond plates, which seemed to tear this steel up significantly less than any of the Japanese carbons I have tried.
I will report my long-term findings once I have the opportunity to test edge retention, but my initial experiences with sharpening are glowingly positive. Because this steel responds so well to such a wide variety of sharpening media, I would say that it would be a fantastic choice for someone working in an environment where Japanese steels might be considered too 'fussy' regarding their sharpening requirements (As literally any tool that falls to hand can be used to sharpen it effectively.), for those with only basic sharpening equipment, or who are just learning to sharpen. The sharpness potential is also stellar... If Robin ever decides to make a straight razor, this is the steel he needs to do it in!
I can also see it as a great steel for single-bevel knives like Usuba or Yanagiba, and for those who prefer working with Hitachi white-paper steel knives of all types.
After working with my Kogatana, the only suggestion I could make would be that hollow grinding the back of the blade would make it tremendously faster for people to flatten. Grinding an ura on the back - whilst more time consuming - would make it significantly easier for people to sharpen this knife as a true single bevel in subsequent batches. Even if the added time equates to a cost increase to 200-300 SEK, I can't imagine people would complain given the time savings, and this is still a bargain to try the steel and the heat treatment for themselves given the quality.
However, that point is a matter of grind, and the point of this exercise was purely to give people an opportunity to test the steel, which I personally found to be stellar.
A question I do have, is if you [Mr. Dalman] are intending to do limited batch runs of Kogatanas (Or similarly simple blades.) in the other steels you use and continue to experiment with (Like 80CRV2, based upon your Instagram.), kind of like the Spyderco 'Mule Team Project'? I can see this being very popular, and as you experiment with more steels I can imagine your potential customers being grateful for the opportunity to try their metal choices before buying a knife.
I hope that this review is of use to those considering buying a knife from Robin in UHB20C (I certainly am!), and I will report back more once I get the chance to use the blade more extensively.
- Steampunk