My knives dull right after sharpening!

[Sheilajeanne]

The problem could be that it's just poor quality steel. Like Art said about certain brands of head knives, they just aren't up to holding a good edge for any length of time.

Not familiar with that brand name - does anyone know if it has a good reputation?

[Jaymack]

+1 on the steel type, quality and temper.

 

[mikesc]

Those edges look "blued" like maybe they have got hot when someone was grinding them ? , if so the temper will have gone off them, in which case they will not hold an "edge" for long at all.

[griley4]

Sounds like it is the steel.....try a different maker if it is possible

[JerseyFirefighter]

8 hours ago, JeannieH said:

So Jerseyfirefighter, do I need to try sharpening at a 15 degree angle? I will have to find a tool to make sure I'm holding it at the right angle. I've just been laying the angle side down on the part where it is flat.

I would think the steel would play a big part in the durability of the knife, however in my limited opinion, using any knife against a solid surface such as granite, glass, OR (as I caught my apprentice doing early on) on top of a piece of steel will create a much faster edge deterioration . I would not cut anything that isnt supported by either a self healing cutting mat, poly cutting board, or even as a quick cut on top of an oak workbench. 

I cannot speak to knife wear while cutting chrome tanned leather, but I believe that Japanese style blades are more finnicky and require a bit more preventative care, regular honing, and expectation that they will need to be sharpened/honed/stropped far more often than a more common blade found in the industry. 

Edited November 16, 2017 by JerseyFirefighter

[YinTx]

Nobuyoshi is supposed to be a very high quality blade.  I don't believe that is a blued appearance from getting hot, I believe it has to do with the types of metal used in the construction of the knife, and the polish done by the craftsman on different sections.  The metal is very hard, can be brittle, and difficult to sharpen.  It will however be capable of sharpening to an extremely thin edge that will hold for a long time.  San-Mai are layered, and can give the appearance you see, as the Jigane and Hagane may take on different hues that shows up in the Shinogi.

These knives are a different world from most knives you see in the leather world, and as such have their own learning curve.  I have yet to master mine - it is the Nobuyoshi , when it is sharp look out.  When it dulls, a challenge for me to get it back to rights again.  Nobuyoshi is super blue paper steel, which is the Aogami steel, which is a very high grade of paper steel.  It is difficult to work with and temper correctly, so it is possible you have one that didn't come out right.  But supposedly this company has been doing it for many years, so they should have the process down pat.  Again, extremely hard metal, difficult to sharpen.  Don't give up on your knife just yet!  Possible you've seen these, but good review on this knife here:

 

And a tutorial on sharpening this type of knife here:

YinTx

[JerseyFirefighter]

18 minute video on how well the knife cuts leather... not one piece of leather cut during video.  I like the look of the knife though. Keeping things sharp are always a pain in the rear. 

[billybopp]

While you would not want to cut through leather on a hard surface, skiving is not problem.  The blade meets the surface at an extreme angle, pretty close to the angle on the blade -  much like it would when sharpening.  

You may need to just stop and strop frequently if the blade is dulling quickly!

Bill

[YinTx]

5 hours ago, JerseyFirefighter said:

18 minute video on how well the knife cuts leather... not one piece of leather cut during video.  I like the look of the knife though. Keeping things sharp are always a pain in the rear. 

LOL, yeah it was a pretty long winded explanation of the knife.  But, I think at the 3:02 mark, that might be a piece of leather making a brief appearance...

YinTx

[JeannieH]

Yintx,  that first video is what made me buy the knife. His review made me feel it was a good one to buy. I have gotten this knife very sharp. Not staying sharp is a downer but I will just keep sharpening as I use it I guess. I will invest in another knife at some point. Any recommendations? Also, the second knife is a double sided Japanese knife I bought from Lisa sorrell. She is a shoe maker. I have the same problem...super sharp then super dull.

Edited November 17, 2017 by JeannieH