# Sharpness question from a newbie - tomato problems



## Mangelwurzel (Jan 14, 2014)

Hi all, I'm new to the board and relatively new to Japanese knifes and sharpening with whetstones.

I'm a home cook based in the UK. I recently purchased a Hiromoto AS gyuto (240mm) from JCK as well as a JCK 400/1200 grit combo whetstone and a JCK 6000 grit finishing stone. I previously used a stainless Sabatier and have practiced my sharpening a few times (using online video tutorials) on that before trying out my Hiro on the stones. I think I've got the basics but there's so much to learn!

I'm a lefty and asked JCK to adjust the asymmetrical bevel on the Hiro from 60:40 to 40:60 (not something I fancied doing myself having never sharpened a knife before!). The OOTB edge seemed quite good to me but my frame of reference is somewhat limited by inexperience. After a week or so of use, I touched up the edge on my 6000 grit stone. I only recently sharpened the edge properly (i.e. 1200 grit followed by 6000 grit, followed by deburring with a cork). 

Since then, I have used it to chop veg and it goes through onions very well; much better than ever before. It seemed really sharp but I haven't done any of the normal tests that people recommend (I did rest the knife edge on my thumb nail and it digs in a little and leaves a small scratch. Not sure if this is a formal test, or what it shows exactly!). Yesterday - and here is the crux of my question - I used it on some slightly overripe cherry tomatoes and it didn't go through them as easily as I'd expect (or as it did with the OOTB edge). It took a good couple of centimeters of pushing to break the tomato skin. And it even squashed some of the more overripe tomatoes. I then tried it on some quite overripe normal tomatoes (that went past their best before date over a week ago) and, again, it didn't break the skin immediately but required a couple of centimeters of movement to break the skin.

My question is: has anybody encountered similar problems with a seemingly sharp edge and overripe tomatoes? And if so, how can I remedy this? Given how the knife performs with everything other than overripe tomatoes (the edge is certainly sharpener than it was OOTB), I am minded to think that one of the factors contributing to the issue is the overripeness of the tomatoes but want to know how I can fix it.

Any tips would be greatly appreciated


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## Von blewitt (Jan 14, 2014)

This video might be helpful
[video]http://m.youtube.com/watch?v=lqsbO1w8rXE[/video]


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## Mangelwurzel (Jan 14, 2014)

Great. Thanks for this. So it looks like I probably polished my edge a little too much.

I guess the best way to fix it is to take it back to the 1200 grit stone again and spend less time on the polishing stone.


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## eighteesix (Jan 14, 2014)

Von blewitt said:


> This video might be helpful
> [video]http://m.youtube.com/watch?v=lqsbO1w8rXE[/video]


I'm not entirely sure this video is accurate. He makes good points, granted, but an edge DOES cut even when there is a mirror finish. The reason the knife slides in the video isn't because the knife has too high a polish. It is likely because it was not sharpened properly, specifically the apex was rounded. 

Just make sure you're paying attention to geometry and do a little more research.


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## dannynyc (Jan 14, 2014)

I love a polished edge for most vegetables, so I keep one knife at a mirror polish and another one toothier for soft tomato skins and the like. If you do this, you will have to keep your polished knife pretty sharp, because as many here will tell you, a dull polished knife is inferior to a dull toothy knife (but, IMHO I'd take a sharp polished knife over a sharp toothy one for 90% of tasks).


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## Dave Martell (Jan 14, 2014)

New sharpeners wobble and thus round over edges easily. Also, some stones in the medium grit level will over polish the edge. When combined these two factors make for a sharp but slick edge, an edge that will slice but not push cut. 

To combat this effect take it S_L_O_W and be deliberate, try to not cut in multi-bevels as these can turn into a rounded over bevel easily on the next stone up in the progression.

Also, it's best to not go much higher than a medium-coarse stone like a 2-3k (max) at first. As you get better introduce a medium-polishing stone (4-6k) that is known for leaving a bite to the edge. No need to go higher than this for a gyuto.


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## Mrmnms (Jan 14, 2014)

A while back, Will Catchside, an awesome maker here suggest I tried stopping lightly on a 2k stone after I finished polished up my bevel, to give some tooth to certain knives. You may try a few edge trailing strokes, lightly, at a lower grit , for soft foods.


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## eighteesix (Jan 14, 2014)

Once you get more accustomed to sharpening, stropping with a diamond spray can really help in this situation. That's fairly advanced though.


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## Mangelwurzel (Jan 14, 2014)

Thanks for all the tips, guys. Dave - I think you may have hit the nail on the head with me wobbling! Any tips on how to maintain a constant angle (other than taking it slowly)?


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## eighteesix (Jan 14, 2014)

Mangelwurzel said:


> Thanks for all the tips, guys. Dave - I think you may have hit the nail on the head with me wobbling! Any tips on how to maintain a constant angle (other than taking it slowly)?


http://youtu.be/GB3jkRi1dKs
http://youtu.be/SKeSRDMRpY0

JKI Sharpening Playlist
https://www.youtube.com/playlist?list=PLEBF55079F53216AB&feature=view_all


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## greasedbullet (Jan 14, 2014)

Honestly I think your biggest problem is that you deburred with cork and then went on to go cut something (If I read your post correctly). After you deburr you should go back to your highest stone and do a few edge tailing strokes very lightly. This will leave you with a burr free, stupid sharp edge that should cut most things very well if not everything.

This is the video (one of them) I learned to sharpen with. He starts deburring around the 6:15 mark. http://www.youtube.com/watch?v=ozZF2EgnYm0

Have fun.


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## Benuser (Jan 14, 2014)

Dave Martell said:


> When combined these two factors make for a sharp but slick edge, an edge that will slice but not push cut.


I would expect an overpolished edge to be fine with push cutting, and poor with slicing.


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## JBroida (Jan 14, 2014)

for what its worth, his finishing stone is 6k... hardly overpolished. I finish many knives at 6k with no problems. I really dont think the grit is the issue, but rather technique- angle consistency, burr removal, etc.


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## xueqi89 (Jan 14, 2014)

i alway sharpen my knife and end with a 6k or 8k stone and is alway overpolished but they still cut through tomato like crazy, actual i use tomato to test if the knife is sharp enough


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## labor of love (Jan 14, 2014)

a properly sharpened 6k edge should slice tomatoes fine, youre probably not spending enough time on your lower grits before you progress.


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## CompE (Jan 14, 2014)

I recommend that you get a loupe or pocket microscope and take a look at your edge. I have something similar to the Carson MM-200. With that you should be able to see if you have multiple bevels or a folded burr fairly easily.


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## Salty dog (Jan 14, 2014)

If I want to cut tomatoes for production I'll use a toothy edge. For a video that has people scratching their heads I go super refined. 
Big dif.


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## Benuser (Jan 15, 2014)

Benuser said:


> I would expect an overpolished edge to be fine with push cutting, and poor with slicing.


Am I in error?


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## Keith Sinclair (Jan 16, 2014)

Salty dog said:


> If I want to cut tomatoes for production I'll use a toothy edge. For a video that has people scratching their heads I go super refined.
> Big dif.



Totally agree cut cases of tomato's wt. 1K edge carbon steel.


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## labor of love (Jan 16, 2014)

yeah for slicing tomatoes and cooked protiens i like 2k edge no doubt, but if youre having trouble slicing tomatoes there is definitely a problem with sharpening technique regardless of the finishing stone grit whether its 1k,2k or 6k.


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## Keith Sinclair (Jan 18, 2014)

Craig I like 2K's also.Wore down my Gesshin 2K.Cherry Japan imports here carries whetstones & knives.Got a sale price on my first Shapton stone a 2K green.Never had a splash & go stone before.I can see how people like these.I like the feedback of Bester & Gesshin stones,didn't know if I would like the shapton.After putting nice edges on 5 carbon knives no problem,deburred on stone as well.Newspaper finish.

I think this Shapton would make a good touch up stone for Gyuto's at work.It is compact,does not need soaking,& can refreash a blade in a heartbeat


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## Geo87 (Jan 19, 2014)

Benuser said:


> Am I in error?



I would agree.. Over polished would push cut but not slice.... Right? 

Also can I point out the OP is talking about 
over ripe tomatoes not tomatoes. My gyuto certainly doesn't slice very soft tomatoes as effortlessly as it does firmer ones...


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## Dave Martell (Jan 19, 2014)

I've found that an over polished and/or rounded edge, under it's own weight, will sit on the tomato's surface until a slicing movement is made and then it falls through. A really crisp and/or toothy edge, under it's own weight, pierces the tomato's skin as soon as it makes contact. 

Using standard white copy paper, rounded and/or polished edges will not push cut straight down unless slicing movement is made. Crisp and/or toothy edges begin to cut on contact with no slicing motion.

This is just what I've seen, I'd like to hear what you guys have found.


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## Keith Sinclair (Jan 19, 2014)

What do you mean by rounded?I think of rounded as losing your crisp edge with incorrect technique.Eg.over aggressive burr removal,sloppy strop,wailing away on steel rod.

For Gyuto's like crisp medium grit edge.Yanagi's polishing stone 4 or 5K enough.Have used 8K.


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## Dave Martell (Jan 19, 2014)

An edge can get rounded in all those ways as well as simply by using chromium oxide on a strop. Sharp as hell but won't push cut.


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## Geo87 (Jan 19, 2014)

Dave: I thought it would be the opposite? 
I.e the toothy edge should need a slicing action and the polished should push cut straight down through paper? 
If I'm wrong please elaborate! 

I've found my gyuto when finished at 5k then stropped on newspaper push cuts paper. 
But a petty used for trimming meat finished at 1k will only slice the paper. 

If I'm wrong then I am very confused so please elaborate! Obviously you know more than I most likely ever will...


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## Sambal (Jan 19, 2014)

Dave Martell said:


> An edge can get rounded in all those ways as well as simply by using chromium oxide on a strop. Sharp as hell but won't push cut.




Dave, how would stropping with chromium oxide round the edge? Do you mean incorrect stropping like lifting the spine at the end of the stropping stroke instead of lifting the entire blade?


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## Dave Martell (Jan 19, 2014)

Geo87 said:


> Dave: I thought it would be the opposite?
> I.e the toothy edge should need a slicing action and the polished should push cut straight down through paper?
> If I'm wrong please elaborate!
> 
> ...




You should consider wire edges, as in you may be using them to cut with. Newspaper stropping is good for re-aligning a wire edge and a 1k stone leaves a decent wire and/or burrs. Sound to me that you didn't finish sharpening. 

I appreciate your input on this, hopefully more people will jump in too.


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## Dave Martell (Jan 19, 2014)

Sambal said:


> Dave, how would stropping with chromium oxide round the edge? Do you mean incorrect stropping like lifting the spine at the end of the stropping stroke instead of lifting the entire blade?




Chromium oxide particles are round like spheres and tend to smooth an edge to the point of slippery from what I assume to be the action of rolling over the apex if the edge. In contrast, diamond particles are blocky & sharp and scratch at the apex making little micro-teeth. 

Incorrect technique isn't what I was talking about.


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## stevenStefano (Jan 19, 2014)

Dave Martell said:


> An edge can get rounded in all those ways as well as simply by using chromium oxide on a strop. Sharp as hell but won't push cut.



I know nobody seems to like it but I still use chromium oxide all the time for stropping. I've tried many diamond compounds and they just don't seem to have as much of an effect as the green stuff does for me


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## Dave Martell (Jan 19, 2014)

Chromium oxide is great stuff and I use it all of the time too.


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## Geo87 (Jan 19, 2014)

Dave Martell said:


> You should consider wire edges, as in you may be using them to cut with. Newspaper stropping is good for re-aligning a wire edge and a 1k stone leaves a decent wire and/or burrs. Sound to me that you didn't finish sharpening.
> 
> I appreciate your input on this, hopefully more people will jump in too.



I am about 90 % sure it wasn't a wire edge as the edge has lasted well,a wire should fail very quickly right? 

So are you saying if deburred properly a 1k edge will push cut straight through paper? 

Note :To deburr I use light stroping strokes with decreasing pressure , cut through cork, then a few very light stroping strokes then move to the newspaper.


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## Keith Sinclair (Jan 19, 2014)

Geoff sounds like good technique to me.All this push pull paper stuff,tried it with newspaper if that counts wt. blades just sharpened on my new shapton 2K.Push & pull no problem wt. 2K edge all carbons.As you said your blades work well in the trenches wt. a 3K S&G touch up stone.

I like to use a strop to finish when sharpening other peoples knives,cuz put on a nice polished edge.I think I maybe the only one still using Adams #2 polish on my strop.Very fine,nice shine.I bought a 16 oz bottle years ago & still have 3/4 bottle.It spreads nice on the leather,cleans up well wt. blue goop when too much metal in the mix.Just wash knives wt warm soapy water.You should do that wt.chrom oxide or diamond slurry too.:bliss:


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## Sambal (Jan 20, 2014)

Dave Martell said:


> Chromium oxide is great stuff and I use it all of the time too.




Please excuse my ignorance on this but if Chromium Oxide particles are round and gives a slippery edge then why do you use it instead of the diamond compound?


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## Geo87 (Jan 20, 2014)

I think Dave was talking about a straight up and down motion through regular paper? No pull or push. 

Yeah most knives I strop on 3k then newspaper. 
Just my petty for trimming meat I stopped at 1k was aiming for more teeth on that particular knife .


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## ThEoRy (Jan 20, 2014)

Sambal said:


> Please excuse my ignorance on this but if Chromium Oxide particles are round and gives a slippery edge then why do you use it instead of the diamond compound?



Different edges for different types of blades.


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## Benuser (Jan 20, 2014)

Not going to speak for others, I tend to find it almost impossible to deburr completely when finishing on a 1k. With stainless this is most obvious. I prefer a further progression and ending with a few very light strokes on the 1k to restore the aggressive bite if needed.


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## panda (Jan 20, 2014)

sounds to me you're spending too much time on the 6k. do most of your sharpening on the 1k, then only use the 6k for a minute or two. 6k is too high for my taste even, i'd just stop at 1200 (finish with light strokes alternating sides each stroke) and strop on cardboard (WITHOUT compounds)


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## ThEoRy (Jan 20, 2014)

Benuser said:


> Not going to speak for others, I tend to find it almost impossible to deburr completely when finishing on a 1k. With stainless this is most obvious. I prefer a further progression and ending with a few very light strokes on the 1k to restore the aggressive bite if needed.



This is what I do on softer steel knives. I don't feel 6k is too high on hiromoto AS though.


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