Tomato Testing

[Thomas Ascher]

Semi serious question. For years I’ve tested the sharpness of knives on how easily they slice paper. SOP. But sometimes I see youtube examples of slicing through tomatoes with no apparent effort. In general, no matter how sharp I get a knife, no matter how finely polished the edge, it seems that I have to saw back-and-forth a couple of times to get slice started on a tomato. Am I lacking something in my sharpening technique or am I living in an area where tomatoes have thicker, tougher skins? Are tomatoes graded according to how thick, tough their skins are? How do I know if it’s the fault of my sharpening technique or the tomato?!

[Geocyclist]

Tomatos are tricky. A “toothy” edge helps a lot, especially to start the cut through the skin as you are talking about.

Some kitchen knife makes make “tomato” knives which are serrated edges, like thiner bread knives.

A dull knife will not slice tomatoes well at all. But a toothy factory edge will go right through. Once you get through the skin the rest is like warm butter. So a toothy edge is good for tomatoes it will not glide though phone book paper.

To get through the first part of the skin try more slicing action, less pushing.

The best is when you have an edge that will slice and slice as thin as a sheet of paper.

[Ken Buzbee]

Like this?

Ken

[Ken Buzbee]

Of course, some would argue for a polished push cut over the toothy edge:

Ken

[Thomas Ascher]

Yeah, the video of the Konosuke HD Gyuto is the kind of thing I’m talking about. I have a couple of Japanese Gyutos that I’ve polished with the WE ultra fine ceramics and come close to this, but not quite. The idea of polishing on newspaper is something I’ve not tried! Gives me something to aspire to. On the other hand, finding some truly ripe, juicy tomatoes might do the trick! 🙂

[Blunt Cut]

A knife with super sharp + sub 20* inclusive angle + thin-behind-the-edge will easily pass this tomato test. This can be easily verify/reproduce by testing with a feather-brand double-edge (DE) razor. Note: DE edge is highly polished.

Tomato in Kono video is fairly firm. Tomato in Miz video is crunchy… Just pondering how those knives fare against wrinkly riped tomatoes :unsure:

[Thomas Ascher]

sub 20* inclusive angle?! Didn’t know such a thing exists! Where? I’ve sharpened my Gyutos to 12* degrees on each side for a 24* angle and even this I find hard to maintain without chipping!

[Blunt Cut]

7* inclusive is my lowest freehand angle on my 24cm v2(steel 64rc) gyuto. Yes was chippy and had a crazy time removing less than 2um tall wire-edge. Ok, that was a little bit passed V2’s steel limit. I micro-bevel around 18* and with subsequence touchups it’s slowly becoming a regular bevel. It would be super cool if WE supports this kind of acute angle sharpening or perhaps too crazy nor practical any way :silly:

[Ken Buzbee]

sub 20* inclusive angle?! Didn’t know such a thing exists!

It really depends on what you use the knife for. As a general purpose EDC I tend to stay around 26°, and even there, they require more maintenance than a 30°-35° edge would, but I find it a good compromise between durability and cutting ability. My kitchen knives I’ll take lower. They don’t see any side to side torsion or hard inclusions 😉 like staples or nails.

I have to say, I LOVE watching that second video. Simply amazing. Guy’s got skills! My wife looked over and said “you’re watching tomatoe porn?” and just rolled her eyes 😉 But she’s used to it. She’s seen me watching videos of guys vacuuming & waxing cars and of course, sharpening knives 😉 OTOH, she has her Photoshop videos 😉

Ken

[Lukas Pop]

Another tomato video: http://www.youtube.com/watch?v=IgqJBF_K6Yc
I think that important is not only sharpening angle but also overall gyuto geometry (thin vs thick). I am looking forward some WEPS modification to attain steeper angles, but was promised about 2 years ago, so probably some technical isues exist.

[wickededge]

Another tomato video: http://www.youtube.com/watch?v=IgqJBF_K6Yc
I think that important is not only sharpening angle but also overall gyuto geometry (thin vs thick). I am looking forward some WEPS modification to attain steeper angles, but was promised about 2 years ago, so probably some technical isues exist.

Very, very soon! Waiting on the samples to come in this week in fact. Somewhere I have a video of a Wicked Edge sharpened vegetable cleaver that does something like that to a tomato too. Super fun.

-Clay

[cbwx34]

Somewhere I have a video of a Wicked Edge sharpened vegetable cleaver that does something like that to a tomato too. Super fun.

This one? (Around the 2min. mark)

[Thomas Ascher]

I really like the Murray Carter video as it demonstrates difference before and after stropping. Can someone clarify for me what “stropping” might mean? I go as far as the extra fine and ultra fine ceramics. What is the next, “stropping” step? Could I get a barber’s strop and use that? What are my options? I tried the leather strops from WE but could never master. Always ended up slicing the strops to ribbons before I got very far with my knives! 🙁

[Phil Pasteur]

Thomas,

You just need to work on your technique. My first set of strops got sliced up badly …very quickly.. I have some that I have been using now for months and there are only a few light nicks in them. There is a learning currve for sure, but it can be done. The key is to always be moving the strop as close to perpindicular to the edge as you can. Never slide it along the edge, and always lift it well clear on the return stroke. Usually what gets you is the tip. Even if you have to recock… start your stroke over once or twice as Clay did in the cleaver viceo… always make sure the you are pusing the strop up and away from the edge.

After the ultrafine ceramics I often use the 5/3.5 micron pastes. Depending on the level of refinement you want, you can go as low as you want from there.

You can strop on many different surfaces if you hand strop. I think a bench strop is easier to use than a hanging strop. I have bench strops in horse butt, cow leater, hard felt and nano cloth. I like lapped horse butt on 5/8″ shelving grade particle board. Murry Carter has videos out there where he strops on newspaper after removing burrs on the edge of a picnic table… 😛 . Some people strop on cardboard, with and without abrasives. Some like to use different types of hard woods. You are only limited by your imagination…and trying things until you find something that works…
🙂

Hand stropping requires you to develop your technique in order to be successful. In many ways it is no different than using the WEPS strops, though they are easier, the machine takes care of your angles! When stropping by hand, youu can screw up a sharp blade pretty quickly by rounding the edge. Or you can waste your time be never hitting the edge. You will also tear up a bench strop if you don’t observe the same sort of rules that I mentioned for direction of movement of the blade relative to the strops as being required with the WEPS strops.

The thing is, if you like the precision that the WEPS provides, you should try and learn to use the WEPS strops. I think that you would be glad that you take the time to get there!

[Mark76]

Some time ago Michiel posted this video on his blog:

I was impressed, so I asked him how he sharpened the blade. The answer was simple: Shaptons up to 15K.

Molecule Polishing: my blog about sharpening with the Wicked Edge

[Author]

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