My knives dull right after sharpening!

[JeannieH]

Hi! I'm going crazy here! I have a 1000/3000 whetstone and stropping block. I have two Japanese skiving knives. I can get my knives sharp on stone. Then I strop..then test..still sharp. But, when I pass the knife a few times through my 3.5 oz chrome leather (on top of treated granite..and tried glass) the knives dull! I've tried not stripping...and my sharpness still doesn't last. I can't possible have to sharpen throughout the day..I must not be doing something right. Any tips from anyone? Thanks!

[fredk]

Its the cutting on glass and the granite is dulling your blades fast. Its okay to cut at an angle, eg skiving, but cutting down directly onto the glass or granite dulls the blades. Try cutting on a self-healing cutting mat, or a piece of MDF/hardboard

 

[JeannieH]

Ok. I'm not cutting with the blade straight up and down...I'm skiving...so I mainly lay the flat side of the knife on the leather with the angle side up. It doesn't appear that the blade is touching the granite or glass at all.  It I will try skiving on my mat instead and see what happens. Thanks!

[gigi]

LW user @gmace99  has useful videos regarding sharpening. For example this one, at the minute 1:12. I think the key for a longer lasting edge is stropping and polishing using a mix like in this video. You can also use a ready-made 'sharpening paste' ('honing compound') and a wool felt sharpening and polishing wheel (motorized).

Making a device to keep the sharpening angle constant might also help.  

 

[JeannieH]

Not sure if my message went through so I'm doing it again.  Thanks for the video.  I've watched so many it ridiculous!  I really take my time when sharpening and make sure the angled side is flat against the stone .  I'm thinking the stropping is where the problem is maybe.  The strop already has the compound on it...you can recondition it with a little olive oil.  It is one sided though.  I put the flat side of the angled side on it and pull back...then put the flat side flat and pull back...I've tried putting a slight angle on the flat side.  Doing that made it very sharp...but omggggg it dulls very fast lol!  Ive tried putting barely any pressure on the knife when stropping...tried putting a little more pressure...still dulls fast after getting it sharp.  I had it cutting like butter and was so happy...then bam...dull when I finished that one little piece of leather!

[Art]

This happens when the steel won't hold a very acute edge. For instance, there are a few (I won't name them) head knives that will take and hold 10 degrees a side (20 degrees included) for light duty. But when the steel isn't up to it, the effect is just as you describe. I have found that 18 to 20 degrees per side (36 to 40 degrees included) works for most leather knives.

Art

[MadHatter]

Chrome tan leather with dull an edge faster than veg tan because it has metalic salt residue in it.

Edge angle will effect sharpness longevity. Also edge concave type will also.

Finding the right balance for all the variables will maximize your efforts.

[JeannieH]

Art, I'm not sure I am getting what you are telling me. Lol. I don't know what the angle is on this knife..it's a Nobuyoshi I ordered from leathercrafttools. The 36mm one. Gigi, yes I have read that the chrome tanned leather dulls the knife faster. I don't have a skiving machine so this is my only option right now unfortunately. 

[JerseyFirefighter]

If Japanese cutlery is anything like kitchen cutlery the blade has a different blade angle (15 degree if I recall) over a more common angle of say 25 degrees or therein abouts. This translates into a sharp edge, but can wear more quickly than a more tapered edge. It has been a while since I researched my own kitchen knives but I do recall that point in case with some japanese blade edge methods vs say a German or American made blade. 

[JeannieH]

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.