Q&A -- Knife Maintenance and Sharpening

[Chris Amirault]

After these two sessions I can really see the advantage in having Japanese style blades due to the annoying bolster.

Someone around these parts gave me the good idea to have my neighborhood lawn mower blade sharpener grind down the bolsters on my chef's knives. It worked like a charm -- though he seemed a bit confused as to why I wouldn't want him to sharpen the knives.

[Guy MovingOn]

15 is pushing it for a final edge on Euro stainless. Are you going to microbevel?

Possibly, but want to see what the edge retention is like at 15 degrees per side...

[Guy MovingOn]

After these two sessions I can really see the advantage in having Japanese style blades due to the annoying bolster.

Someone around these parts gave me the good idea to have my neighborhood lawn mower blade sharpener grind down the bolsters on my chef's knives. It worked like a charm -- though he seemed a bit confused as to why I wouldn't want him to sharpen the knives.

Not sure if we have people offering that kind of service over here in the UK... although I've thought about taking them to the local mechanic/garage to see if they could grind down the bolsters...

Btw, does anyone have a good recommendation for the angle at which to sharpen a European style boning knife? Also any advice on how to sharpen the curved point using the EdgePro?

[Dakki]

15 back and a 20 microbevel works fine for me on both Euro chef's and boning but you can see I'm on the conservative side. I think most of the performance benefit of thinning out the edge beyond a certain point comes from the back bevel not offering as much resistance, while the thicker microbevel is much more resistant to fracture and deformation (and much less of a PITA to maintain).

This is basically analogous to convexing, supposedly a high-end sharpening skill. I say supposedly because everyone convexes to some degree sharpening freehand.

So... go to 15 and back off a notch to create a microbevel if the edge starts failing on you?

[Guy MovingOn]

15 back and a 20 microbevel works fine for me on both Euro chef's and boning but you can see I'm on the conservative side. I think most of the performance benefit of thinning out the edge beyond a certain point comes from the back bevel not offering as much resistance, while the thicker microbevel is much more resistant to fracture and deformation (and much less of a PITA to maintain).

This is basically analogous to convexing, supposedly a high-end sharpening skill. I say supposedly because everyone convexes to some degree sharpening freehand.

So... go to 15 and back off a notch to create a microbevel if the edge starts failing on you?

Good advice. I will just sharpen everything to 15 degrees per side.

So far I have been sharpening everything up to the 6000 grit tape, which is the equivalent of a 18000 grit Japanese waterstone. I'm thinking of sharpening the boning knife and carving knife up to 1000 grit EdgePro stone (8000 grit Japanese waterstone equivalent) only, so that it would have more "bite" for cutting.

What do you think?

I also think I need to have less of the blade edge sticking out over the blade table, I feel like I have been filing away too much metal and working too hard to reach a burr.

[Dakki]

In no order:

Thinning the edges on a factory Euroknife down to 15 is going to take hours and hours. If I'm understanding you correctly you have the edge stuck out a bit further from the edge of the supporting table than you think it should be; this would make the base of your triangle slightly longer, which will make the edge slightly thinner, which indeed would make the process take somewhat longer. However, I wouldn't worry too much about it. You're basically grinding down some very hard metal with a very fine file and taking off any amount of material is going to take time. This is another reason I favor microbevels. The amount of metal you take off each time you sharpen is much, much less, making the process that much faster (and encouraging you to do it more often, which in turn means you have really sharp knives every day, which coincidentally means -less- wear on your knives in the long run if you sharpen them often. Neat, huh?).

One time-saving tactic you can use on a previously-unsharpened knife is to do it in steps. Make the angles 25 the first time you sharpen, then drop it down to about 22.5 (approx) the next time and so on. Two things I've learned from doing things this way is that you can get things surprisingly sharp even with a relatively fat edge, and that a lot of knives leave the factory with no edge at all. (I'm NOT saying 25 is an adequate angle for a chef's, just that you can do this to break up those long, long sharpening sessions into more manageable amounts of work).

A time-saving skill you'll acquire in time is learning to recognize a burr when it has barely formed. Using a fingernail to "scratch" the edge (from the back towards the edge, if you follow) allows you to detect a burr when it's still invisible to the naked eye. A strong lamp and a loupe or magnifying glass are also useful for this.

As for the grit, 6000 tape on everything may be going a bit overboard but I'll be the last person to discourage anyone from polishing to their heart's content. I'm not a believer in the whole microserration thing (I think the supposed superiority of "toothy" edges is a tactile illusion and I've found highly-polished edges last much longer), however the 1000 grit EdgePro stone is very fine indeed. I think you'll do well with this.

About polishing, before taking a knife from one stone (call it #2) to a finer one (call it #3), make sure you polished off the grind marks from stone #1 completely. Here, again, a strong lamp and a loupe are invaluable. I know it sounds obvious but I've seen a lot supposedly well-stropped knives with big fat scratch marks from the coarse stones still on the edge. This defeats the purpose of the finer grits.

[Guy MovingOn]

Thanks for the suggestions!

I'm quite sure I did have the edge of the blade sticking too far over the blade table, I was spending 1-2 hours on the 120 grit stone just to reach a burr. I can also see I have changed the profile of the knives somewhat. I have found it hard to maintain the "belly" or curve of the knife when using the EdgePro. Perhaps I need more practice and to adjust the position of the knife more frequently, or perhaps I have been applying too much pressure.

I think eventually with the EdgePro it will be hard to maintain a curved profile to the blade edge, and instead you will end up with a series of small straight lines forming an arc... if you can understand what I mean?

Has that happened to you?

[Dakki]

It hasn't happened to me but I do know what you mean, I was curious about this effect too at first. If it makes you feel any better, remember calculus: a curve is just a series of infinitesimally small straight lines. You probably should adjust the knife position more or less constantly to get contact with all of the edge once you've cut down all that extra material at the shoulder (upper edge of the bevel), and use whatever play your unit has to your advantage. Less pressure is always a good thing. Remember the useful work you're doing is dragging the stone across the edge, the downwards force you apply to it is wasted at best and can actually deform the edge.

Keep at it. Once you've done a few knives everything becomes very clear.

[scubadoo97]

I haven't had any problem following the belly on my german chef knife which is the knife in my kitchen that has the most belly. Using too much pressure is a common mistake with new users

[Blether]

In the Stroke demo'd on the EdgePro DVD, the stone sweeps a width of edge that's more than the width of the stone. And why would a flat traditional sharpening stone be a better bet for a round edge than a flat EdgePro stone ?

[Dakki]

Noticed this week we have a whole bunch of unused abrasive stones at the shop. These come as freebies when we buy a diamond grinder cup (they're used to clear the cup from metal particles that can clog it) and are unmarked in any way; the sales guy for the supplier doesn't know anything about them, either. Grits vary from "ridiculously coarse" to "somewhere between medium and fine" (determined by touch). I grabbed a couple of the finest ones. These appear to be white aluminum oxide and measure roughly 2x10 cm (~0.8x4").

Out of the box these presented a jagged, uneven surface that was much too rough to be used on a knife but a few passes over a worn-out file broke off enough of the peaks to make them usable. They also had some small stained with what looks like some brown liquid (machine coolant from the manufacturing process?). Obviously QC is not a major concern on a "freebie," and neither of these small defects interfere with the original intended purpose.

I freehanded an edge on my good ol' Dutch-issue Victorinox. Stone was moistened in water before use. The stone's small size would have made tabletop sharpening very awkward so I held the stone in a three-finger pinch in one hand and moved it over the knife held in the other, always moving away from the edge. Edge is rougher than I prefer but it shaves arm hair perfectly.

(Knife for scale. Dimensions are identical to a standard Swiss Army Knife.)

As you can see from the photo, the surface of the stone is not flat, but wear will even it out. The stone has some tendency to clog, which is expected of aluminum oxide; a scrub with an old toothbrush and some powdered dish detergent (or even a little hand soap) will clear the material.

I won't suggest these stones are a replacement for an EdgePro or some good bench stones but I think they're just the thing to keep in your toolbox, tackle box, etc. for emergency maintenance.

[dcarch]

A good large sharpening stone can break your piggy bank.

Slate tiles can make acceptable sharpening stones. If you have a friend or if you have a diamond cutting saw, it is very quick and easy to cut a few blocks and sand paper the surfaces flat.

Before you do, use a magnifying glass to examine the grain structure first. There are many different types of slate tiles.

dcarch

[ScoopKW]

Buy your stone from a hardware store, not a kitchen supply store and you'll pay a LOT less.

A good 1000/6000 grit Japanese stone can be had for less than $35.

[Zingledot]

I'm curious about the MinoSharp wheel systems - more accurately, I have one, but I'm curious about it's relative effectiveness compared to an actual stone.

They are somewhat curious in how they apply the techniques in this course. Both in how they achieve it, and in that I now know how much is going on when you push the blade through the wheel.

First, as the wheels spin on the blade, I imagine they make a motion more akin to pushing it over a stone than dragging across a V-shape, as it typical with hand-held gadgets.

Second, the wheels are angled horizontally, as well as beveled vertically. This seems to keep the edge away from direct contact with the bottom, allowing it to be ground from the sides. But I'm not sure if the angle that it contacts the wheel matters at all. Being a rounded surface, it only makes contact with the highest point.

Third, the wheels do both sides at once, so I imagine no discernible burr should appear on either side, but how does this relate to the stropping techniques? Do you need to strop an edge with no burr?

Fourth, they are ceramic wheels. Chad covers ceramic only in reference to steels, but doesn't go into detail on how well they'd work as the primary abrasive - is there any reason to think it wouldn't be a good abrasive surface?

-Aaron

[Dakki]

Not familiar with the product you describe, and my sharpening routines are different to the ones in the course, but I think I can answer some of your questions.

Third, the wheels do both sides at once, so I imagine no discernible burr should appear on either side, but how does this relate to the stropping techniques? Do you need to strop an edge with no burr?

There is no question of need. Stropping is an optional step, so long as the burr has been properly removed on your finest stone.

There can be benefits to the finish when stropping, however, if your stropping abrasive is finer than your finest stone.

Fourth, they are ceramic wheels. Chad covers ceramic only in reference to steels, but doesn't go into detail on how well they'd work as the primary abrasive - is there any reason to think it wouldn't be a good abrasive surface?

Short answer: No reason.

Longer but still woefully incomplete answer: The term "ceramic" covers literally hundreds of materials. If you have artificial stones they are most likely ceramic, and natural stones are simply naturally-occurring ceramic. The relevant questions here are particle size and hardness. Finish will be determined by particle size and speed in sharpening will be determined by a combination of both factors plus technique.

[knyfe]

Well I just found this article, great. I have already shared it several times. I have realistically, a few too many knives. I am sure most people here understand. Mostly they are Shun, I am able to purchase them at the annual Kershaw knife sale at the manufacturing plant in Wilsonville Oregon. They will sharpen them for free but I have hard mixed and sometimes poor results. I think that the Edge pro apex system 3 is the best option for me. At $225.00 it may seem high, compared to the knives I need to sharpen it does not. The 3 system has a better range of stones. Are there any new concepts or systems out there I may have missed looking at? It seems to me that the Edge Pro systems wild be the most consistent.

Thanks, David