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Thread: I've been learning about and sharpening knives the past few months, and I have quite a few questions

  1. #1
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    I've been learning about and sharpening knives the past few months, and I have quite a few questions

    I consider myself a journeyman on knives and knife sharpening (I know more than people who don't care much for knives, but I don't consider myself an expert), and I'd really like to take my knife sharpening skills and knife knowledge up to the next level so I have a multitude of questions I'd like to get answers to. I've watched Jon and Carter's videos on YouTube, and I've been reading this forum along with zknives for awhile. I'm a really picky person though, and there are just a lot of things that I'm still curious about that I'd like to get more information on.

    Anyways, here goes:

    1. What about diamond stones? I currently use water stones with a diamond plate for flattening, but it seems like diamond stones come in pretty fine grit now too. Why does everyone advocate the use of water stones over diamond? The only disadvantage I can see would be that the diamonds would cut much more aggressively with leaves less room for error, although this maybe an advantage for some because it'd cut quicker. It seems like the feedback on diamond stones would not be as nice as water stones either, but I think this is a personal preference matter.

    2. What am I suppose to be looking for when using a loupe? I bought a loupe because they're cheap, and I kept seeing people say to check your edge with a loupe. I'm seeing things with it, but I'm not exactly sure what these things mean. Any nicks and chips, I can usually spot with my naked eye if I try hard enough, although the loupe does it make easier to spot. I noticed different colors (or difference degrees of shine) on my edge bevel when I first started sharpening, and I felt that this meant I was not holding my hand steady enough thus changing angles while sharpening (thankfully, I'm better at it now). Is my assumption true, and what else can I use loupes for when it comes to knives?

    3. How do I deburr on cork and soft wood? I've tried doing this a few times where I deburr by lightly cutting a knife into a wine cork (does it matter if the cork is synthetic or natural?), but I've always felt a burr on the knife after cutting through cork. I've been practicing with my coworker's German knives, and I've read that the softness of the steel makes the burrs more difficult to remove. Could this be part of the reason as to why this deburring technique doesn't work for me? I usually just end up using a fine ceramic rod or stropping lightly on my Suehiro Rika 5k to remove the burrs. I did just get a balsa strop which I loaded with chromium oxide paste and a leather strop (natural cured, cowhide), but I haven't really used it much yet.

    4. Should I be worried about swarf contamination in my stone soaking water? My current stone set up is a King 1k, Bester 2k, and Suehiro Rika 5k, and I usually soak all three stones in the same container or sink. As I sharpen my knife, I'll splash water onto the stone using the water from this container, and I'll periodically wash my blade off which causes the swarf to contaminate the water. When I switch to a finer stone, I'll rinse the stone off real quickly, but should I be changing the water too so the coarser grit stone material doesn't affect the performance of the finer stone? For now, I change the water just to be safe, but I believe that clean water is very precious (I studied crop science in college, and our water supply is my biggest concern over other stuff like fertilizer and pesticide use) so I try to not to waste any if I can. Also, should I be washing the swarf off periodically? I've read that the swarf actually does a lot of the sharpening, so I try to keep it on, but is there a point where I'm leaving too much on?

    5. How big of a concern is stone clogging with water stones? I'm noticing grey streaks in my stones as I sharpen, but due to this series of comment on Reddit, I believe that stone clogging is more of a concern with oil stones than water stones. I feel like water stones are usually soft enough that the sharpening motion will simply knock out metal and stone particles, and as a result, I shouldn't have to worry about clogging. I also haven't noticed much sharpening issues with these streaks in my stones, but like I said, I'm still learning about knives so I might just not be experienced enough. I'm assuming I can just use the little stone cleaners or lightly lap my stones with a diamond plate to unclog if clogging is an issue.

    6. How flat does my stone have to be, and how can I tell if my stone is slightly dished? I also feel like the flatness of the stone matters more depending on the type of knife I'm sharpening, like a single bevel knife or very flexible/whippy knife, but can anyone confirm this for me? I try to use Carter's suggestion with spotting high spots on the stone and sharpen more in this area. I tend to notice high spots on the corners of my stones, and I rotate my stone when I'm sharpening so I wear it out more evenly. I also try to do most of my tip sharpening in these high spots. However, how flat does the stone have to be? I usually use a flat surface, and I just lay the stone against the flat surface to see if I have any indents, although I feel like this means the stone has to be pretty dished for me to see it. Should I be using another method, perhaps a level?

    7. Should I be flipping the knife periodically as I sharpen? I've read some suggestions that I should just be sharpening one side until I feel a burr, then repeat the same number of strokes on the other side. However, I feel like this will cause uneven grinds, and I try to flip the knife every so often. I feel like I'm not being consistent enough with it, and it seems like one side of my knife is getting ground more than the other side. My beliefs are a result of observing the choil, and it just seems like a certain side is more slanted than the other when I don't flip the knife regularly during sharpening.

    8. How can I tell if I have an overgrind and possible ruining of heat treatment? I've been thinning my knife because it's pretty thick behind the edge (it's a Richmond Artifex, I'm using it as my beater/learning knife), and I noticed a low spot on my edge (I'm calling it a low spot because I'm holding the edge upwards, although if the edge was down on the board, it's be a high spot). At first, I thought I just screwed up when sharpening/thinning it as I don't have a smooth motion down yet (I sharpen in sections and try to keep count of strokes, slowly progressing to less counts), but after reading the thread about Moritaka's overgrind, I'm beginning to suspect that it's an overgrind. The reason I suspect this is because I'm starting to see discoloration (like purplish-blue tint that's slightly reflective, almost like soap streaks on a water surface) on the surface of the blade behind where this spot, and it's only starting to show up as I've thinned and expose the inner metal. Is this discoloration of any concern? I'll try to get a picture of it, but I feel like it's going to be difficult to get the right light and angle for it to show up on a picture. I wish I had known more about overgrinds when I first got the knife, but I didn't really know how to spot them when I first got it a few months back so I don't know if this was an issue from the beginning.

    9. How do I sharpen the flexible German boning knives (or any flexible knives in general; I've yet to had the pleasure to use a laser), especially around the heel where there's that curve. Perhaps I should just not care about sharpening this curve though as it doesn't really get much use anyways.

    10. How does knife geometry affect food release? I've been watching all the videos on food release in the media center section of the forum, and I'm just confused as to why the Gesshin Heiji seems to perform so well in this category. I've read that the Gesshin Heiji's grind is a little bit concave, and this improves food release. However, I read on zknives that hollow grind increases drag, but maybe drag doesn't have the effect that I think it does.



    Hopefully, these aren't too many questions. I don't like to say thanks before someone does something because it seems presumptuous to me, but any answers provided will be greatly appreciated.

  2. #2
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    Quote Originally Posted by Flyingpigg View Post
    1. What about diamond stones?
    I've used them, and they work quite well, but as you note, there is little or no feedback, so they are not my favorite for general sharpening, but they are great for thinning, because they don't dish, ever.

    2. What am I suppose to be looking for when using a loupe?
    All a loupe does is make it easier to see things like faceted bevels instead of clean, flat bevels, and if you are hitting the edge when using the "marker trick". No magic here, just an aid to those of us with older eyes.

    3. How do I deburr on cork and soft wood?
    You make a shallow cut into the cork, felt block or soft wood and the slicing action should tear the burr off the edge. If you are having troubles, it may be because the connection of the burr to the edge has not been sufficiently weakened by working both edges alternately. Try trailing edge stropping to help weaken the burr.

    4. Should I be worried about swarf contamination in my stone soaking water? Also, should I be washing the swarf off periodically? I've read that the swarf actually does a lot of the sharpening, so I try to keep it on, but is there a point where I'm leaving too much on?
    You should be rinsing off your stones as you remove them from your soaking water, and it's not a bad practice to rinse them before replacing them. It doesn't require a lot of water - a quarter cup should be sufficient.

    5. How big of a concern is stone clogging with water stones?
    The thing about waterstones that makes them different from oil stones is that the surface of the waterstone is constantly abraded to reveal fresh sharpening material. It's really hard to clog one, but if it happens, it's usually because your not using enough water during sharpening.

    6. How flat does my stone have to be, and how can I tell if my stone is slightly dished?
    Use a straight edge to judge how dished your stone is, as Jon Broida illustrates in this post:
    http://www.kitchenknifeforums.com/sh...l=1#post238350

    For me, less than 1 mm of "dish" is acceptable, but YMMV.

    7. Should I be flipping the knife periodically as I sharpen?
    Yes, but here's where that loupe can help you, if you use the marker trick to tell you when you hit the edge rather than trying to detect a burr.

    8. How can I tell if I have an overgrind and possible ruining of heat treatment?
    Overgrinds generally do not affect the heat treatment. There is a whole tread about overgrinds, and how to determine if you have a real problem. Again, Jon Broida summed it up well in this post from the thread:
    http://www.kitchenknifeforums.com/sh...l=1#post235100


    9. How do I sharpen the flexible German boning knives (or any flexible knives in general?
    Very light pressure is the key to sharpening a flexible knife. It's tricky. The recurve area can be sharpened with a curved hone, or with a dowel wrapped in wet/dry of the appropriate grit.

    10. How does knife geometry affect food release?
    Generally speaking, the more convex the grind, the greater the tendency for what is cut to be pushed away from the side of the blade as the cut progresses. There are more factors at work here than just geometry - the characteristics of the product that is cut, for example. A soft cheese will stick to most every knife, while a hard, fibrous sweet potato won't. A mirror polish on a knife with minimal convexing is probably the worst offender, at least in my experience. Keep in mind that there is a trade-off here, in that knives with really convex grinds usually don't "fall through food" well.
    “I hear and I forget. I see and I remember. I do and I understand.”

  3. #3
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    This is useful information! Thanks.

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    Senior Member Seb's Avatar
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    I have read that diamond plates are too hard to use for sharpening Japanese knives as they will cause micro-fissures/chips. I haven't tested this theory out for myself but it sounds good enough for me.

  5. #5
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    Quote Originally Posted by Seb View Post
    I have read that diamond plates are too hard to use for sharpening Japanese knives as they will cause micro-fissures/chips. I haven't tested this theory out for myself but it sounds good enough for me.
    Seb, I think that meme is right up there with the "VG10 is chippy" one.

    Rick
    “I hear and I forget. I see and I remember. I do and I understand.”

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    Thanks for the information.

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    Senior Member Seb's Avatar
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    Quote Originally Posted by Pensacola Tiger View Post
    Seb, I think that meme is right up there with the "VG10 is chippy" one.

    Rick
    Haha good point. Thanks for questioning.

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    Senior Member EdipisReks's Avatar
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    Quote Originally Posted by Pensacola Tiger View Post
    Seb, I think that meme is right up there with the "VG10 is chippy" one.

    Rick
    yup.

  9. #9
    When the diamonds are electrically plated to the surface, they can have a lot more surface area exposed, and this can sometimes cause what's seb is talking about... Especially when coarser grits are involved. It's because they will cut deeper in this particular kind of scenario.

    But if you spend enough time going through your progression, all of the problems caused by this coarse grit diamond will be gone.

  10. #10
    Quote Originally Posted by JBroida View Post
    When the diamonds are electrically plated to the surface, they can have a lot more surface area exposed, and this can sometimes cause what's seb is talking about... Especially when coarser grits are involved.
    I'm curious about this myself. I only use DMT plates...all the others I've tried are horrible...the diamonds roll out and seriously scar up the work. Not to mention they just plain aren't flat.

    I also noticed that the difference between extra coarse, and extra-extra coarse...is like a million miles. Extra-extra is like 27 seriously large diamonds bonded to an 8x3 plate, lol. Extra was actually relatively smooth once broken in. I love the way it cuts. I'm not using those grits for sharpening though...so I'm sure that makes a difference.

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