What edge for tomatoes?

bpeezer

bpeezer

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Jan 27, 2013
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A friend asked me to sharpen some knives. When I asked how sharp, they said "to slice ripe tomatoes without smashing them at all." Unfortunately, I've never really cooked. I have absolutely no idea what kind of edge is needed here. Recommendations?
 
sharp! but seriously any thing over 1000 grit and then stroping would be preferred but you could use 320 is and then strop real well.
 
I roll up a paper towel tightly and test the edge by slicing through it. This is my usually my final test after making sure the edge is burr free and sharpness is where I want it. Depends on the knife. If you get a good clean cut deeply through that your edge should be good for tomatoes (as an example).
 
I have found that a little "tooth" left on the edge works great on ripe tomatoes. I sharpen with my paper wheels and then lightly run them on the slotted wheel to remove any burr. I test with a Q tip and if it hangs a little on the cotton tip along the edge, then it is just right for tomatoes and slicing raw meat. The toothyness (new word, not found in dictionaries:D) seems to break into the tomato skin without any effort or damage to the tomato.

Blessings,

Omar
 
You want a toothy edge, like suggested. You basically get that by either jumping from a lowish grit to strops, or by running the blade edge trailing a few passes on a finer stone, them stropping.
 
I prefer to be able to push cut my tomatos. 160,000 plus :)

Doesnt take anything too fancy to slice though. A good 5k plus edge will be fine.
 
Good to know. A dull knife might as well be a hammer when dealing with tomatoes.
 
Thin edge geometry + a very crisp apex are really all you need. If you have that, it doesn't really matter what degree of finish you put on it, from toothy/coarse to high polish. The quality of the steel itself will impact that; softer & less durable typical stainless kitchen knives won't hold a fine edge as well, so a toothier edge usually works a little longer, and is easier to apply. Something like 320-grit works well on those. Higher quality, wear-resistant steels that support thin edges well can be polished to mirror or nearly so, with little/no loss in sharpness or edge durability. Those are a dream to use, at thin geometry and high polish.

As examples, I have an old cheap Japanese-made paring knife in unknown stainless 'mystery' steel. It has never been able to hold a high-polished edge well; the 'bite' goes away very, very quickly, almost as if the very fine micro-teeth just crumble away in use. I have settled back into using 220/320-grit wet/dry sandpaper for that one, or an inexpensive hardware store SiC stone works pretty well for it also. I even used a black emery board (as for fingernail filing) to put a great working edge on it. On the flip-side, I have a 'Folding Cook's Knife' in VG-10 (A.G. Russell) and an Opinel in Sandvik 12C27Mod that both take a very high polish and still retain some nice 'bite' in their very thin edges. Both hold up pretty well also; I use some Ryobi 'White Rouge' compound on a hard-backed paper strop to maintain them.


David
 
I like a bit of tooth on kitchen knives, so I only sharpen to 8000 grit and then lightly strop. On most knives, 10 degrees per side will cut quite well.

When using the very high quality (and high dollar) Japanese knives, 7.5, or even 5
dps is often practical.

I like to put the point of the knife on the board, and lower the handle to about 45 degrees, and "pull" the knife through the tomato. This gives a combination of push cutting and slicing, but without allowing the cutting edge to touch the board, thus preserving edge longevity..

If the blade will not "slide" through the tomato without back and forth sawing motions, you need to sharpen it more.
 
A lot of folks that don't know how to actually put a sharp polished edge will say toothy, but that is incorrect. The thinner, higher polished and most refined edge will cut the best for this.

Here was a cool test that started in the traditional section. I grabbed my machete to see if it would pass ;)

[video=youtube;5qGxaIxKmq4]http://www.youtube.com/watch?v=5qGxaIxKmq4[/video]

Kevin
 
I sharpen a kitchen knife for a friend probably once a month and I sharpen it through all my stones 100-1000 then ceramics. He has never complained about the sharpness.
 
Jastab said:
I sharpen a kitchen knife for a friend probably once a month and I sharpen it through all my stones 100-1000 then ceramics. He has never complained about the sharpness.
Click to expand...

:D:D Several years ago, I sharpened good Japanese kitchen knives monthly for a dear friend and colleague.

I sharpened to 30,000 on water stones and then stropped.

One evening, my wife and I were invited to dinner at his home. We arrived a bit early, to find his wife slicing beef roast on a china platter.

I "casually" mentioned the advantages of a bamboo cutting board, and immediately had my head handed to me by his wife. She was quite upset that I, a male, "presumed" to know more about food preparation than she did. :mad::mad::mad::mad::mad:

(Of course, since she was a social anthropologist, I should have expected that reaction.:D:D)

From that day forward, his high dollar knives received a 2000 grit water stone sharpening, and his dear wife never knew the difference.:yawn::yawn:

(It did somewhat break my heart a bit though to take a $1400 Hattori Gyoto off the bench with only 10 percent of the work done):(:(
 
richstag said:
A lot of folks that don't know how to actually put a sharp polished edge will say toothy, but that is incorrect. The thinner, higher polished and most refined edge will cut the best for this.



Here was a cool test that started in the traditional section. I grabbed my machete to see if it would pass ;)



youtube video



Kevin
Click to expand...
I can't say I completely agree with you. Yes, a high polished edge will cut tomatoes quite well. Better than a toothy edge, in fact. However, to keep it that way, you need to strop it often, and steeling it, like a chef would, would ruin its cutting ability. A toothy edge, however, will stay cutting well for a far longer time, similarly to serrations. As a plus, steeling will realign and refresh the edge, and keep the blade sharp for an extended period of time.
I can make both edges, I shave with a straight razor and all of my blades are mirrored at the edge. However, a toothy edge makes a better, longer lasting slicing edge.
 
As you call tell by reading the posts there is a difference of opinion on what a "Toothy Edge" is?
When I started knife making and sharpening for a living back in 1996 I thought "Toothy" was better. The more I sharpen the more I go for a fine poised edge of 20%-11% depending on the knife & culinary task at hand,

For all Euro/ Americana culinary knives I sharpen to at least 600 grit and then polish on the buffing wheel loaded with green chrome. Japanese knives get taken to 2000 and then buffed as well.

A finely sharpened edge will not tear at the food like a serrated of Heavy Toothy edge will.

When you disrupt the cells of the food, you diminish the taste. keep experimenting and find what works best for your given task?
 
I don't mean this in an offensive way but just because you can produce an edge to shave with doesn't mean you can produce a durable polished edge. That machete was USED before that video. I don't mind you disagreeing whatsoever, but for cutting tomatoes you won't dull the edge.

I actually give my EDC knives a toothy edge, read 1200 grit followed by linen/black compound strop, because it will keep going longer. But for tomatoes, a well executed polished edge will cut them all day long. As for a chef, got me what works best, Im not a chef.

Also, I don't use a steel to upkeep my polished edges. I use a Kalamazoo, leather belts and multiple compounds on them.

Respectfully.

Rennd said:
I can't say I completely agree with you. Yes, a high polished edge will cut tomatoes quite well. Better than a toothy edge, in fact. However, to keep it that way, you need to strop it often, and steeling it, like a chef would, would ruin its cutting ability. A toothy edge, however, will stay cutting well for a far longer time, similarly to serrations. As a plus, steeling will realign and refresh the edge, and keep the blade sharp for an extended period of time.
I can make both edges, I shave with a straight razor and all of my blades are mirrored at the edge. However, a toothy edge makes a better, longer lasting slicing edge.
Click to expand...
 
Thanks for all the replies! The knives are real cheapos, so I'll probably give them a 400 grit edge and strop them lightly. I might take one of them up to a mirror polish, and ask for feedback on both edges.
 
I find a polished toothy edge is best. Jump from 600 or so to green CrOx strop, then bare leather. It makes a happy medium between the both.
 
Here is another video of the same machete. As you can see the edge can easily handle any tasks.

[video=youtube;fX95Kil5t0s]http://www.youtube.com/watch?v=fX95Kil5t0s[/video]
 
Took me a long time to write this post... yep it's still sort of incoherent :rolleyes:

Tomato skin fracture Pressure threshold = (Force / edge_contact_Area). Let's qualify P need to be small, which won't smush the tomato. Also let's ignore force vector and toothiness rip/tear by-product.

For given F and A=(edge Width * Segments * sEgment length). To achieve atleast minimum P, you can play with W, S, E. Further more, if we reduce [E] = a point/sharp_tooth; what left is just W & S variables. Where:

* W=sharpness. Apex width.
* S=number of tooth. S increase as as the tooth size (more refine) decrease.

So certainly there are points where sharpness are insufficient for a given large number S. By decreasing S (larger; coarser teeth), would directly reduce Area, which possible to achieve sufficient pressure to fracture tomato skin.

A reasonable great edge for tomato = shape a 1K edge where every tooth is sharp as possible from crest/tip to trough.
 
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