What level of grit to use for sharpening knives

Discussion in 'The Mess Hall' started by binder, Oct 8, 2010.

  1. I have a knife I tried to sharpen. I used a stone I bought at Home Depot. It seemed to set the bevel OK. I then used wet/dry sandpaper: 1000 and then 2500 grit. I don't know if it made it any sharper, but seemed to polish it. I don't have a lot of experience, so I probably need practice. I also have some Edelstahl knives I want to sharpen.

    My question is what size grit is good to start with, and how do I progress up, and how high a grit would I go to with these knives?

  2. DaveMartell

    DaveMartell Vendor

    It doesn't pay to go very high in grit size on German knives and in fact it likely makes for a shorter lived edge if high polishing. I would use your Arkansas stone (I think that's what you might have) and deburr on some leather and be done with it. The reason for this is that the knife's steel properties and heat treat aren't likely to provide for good edge retention anyway so it's better to leave the edge rougher so that it bites and grabs even as it goes dull.
  3. ouch

    ouch Moderator Contributor

    If you, for whatever reason, choose to have a single stone, I'd suggest a 1K. This may have already been recommended to death, but the reasoning is sound. A 1K can create a perfectly serviceable, if not impeccably polished, edge, and can restore a fairly dull edge, although you may have to work at it for quite some time.

    One of the main reasons for having an assortment of stones is to save time- you can spend just a few minutes or less at each stage and quickly go from dull as can be to good enough to use.
  4. Will 1000 grit be enough to use for chopping vegetables or slicing? I used the knife after the 1000 grit sandpaper and it didn't chop things like celery very well. Maybe it was the knife or my technique; the one I sharpened was: True Edge from the Ontario Knife Company, made is USA. I heard of people sharpening at 3000, 6000 or more.
  5. Jim

    Jim Moderator

    Going higher than 1000-1200 on a "soft" knife is an exercises in frustration.

    As Dave mentioned above it can actually make the edge easier to roll.The harder the knifes steel, the more useful it is(OK OK generally, easy now:tongue_sm) going to higher and higher grits.

    Some of the Old hickory knives( I think thats what you have) are pretty good and you should be able to chop and slice easily.

    I would suspect you have a sharpening technique issue at work here.

    Here are some vids for your perusal
    Part 1
    Part 2
    Part 3
    Last edited: Oct 9, 2010
  6. In professional kitchens I would often improvise on the sharpening stone because there wasn't one in the kitchen. The knives were sharpened once a week by a sharpening service, and the abuse they took made them dull by the end of the day.

    I've used ceramic dinner ware with good results. China coffee cups with a raised rim on the base worked well. Even a piece of leftover floor tile worked for. The one common thing that I did with them all was to finish the edge with a steel, spending the time it needed to polish it.
  7. Do I need to soak this stone?

    The Knife is an Old Hickory.
    Thanks for the videos.
    I sharpened with a sweeping motion. Maybe that was the problem. I thought sharpening in sections wouldn't give a uniform edge, or can this be compensated for?
    What angle could a person go down to on these knives?
    Does going to a higher grit give a better cut or more for polish?

    Thanks for replies
    Last edited: Oct 10, 2010
  8. For my decent quality Solingen knifes I use a diamond plate @ around 600 grit & then finish on a King 1K.
    That leaves an edge that is servicable for a long time & I can easily cut thin slices from a freshly baked loaf of bread.
    Good enough for me.
    Just for kicks I tried with a smaller peeling knife to take it all the way up to Naniwa 10K, but it didn't do much.
    One dinner later the edge was back to about 1K edge.

    I also have a leather bench-strop loaded with 2um diamond paste that I use every now & then.

    My wood-working tools generally gets the same treatment.
    Except for the axes, they have to settle with carborundum.
  9. Things I've learned about sharpening. These are my opinions and everyone has their own.

    Technique is more important then your sharpening tools. It's also important to understand that everyone has their own technique, but each personalized technique achieves the same goal, metal removal.

    Sharpening any metal is about metal removal. You want to remove metal to create an edge, the finer you can remove that metal the finer you can get that edge.

    When you look at a knife under a microscope you will see that the edge is serrated. There are microscopic teeth on the edge of the blade. The ideal edge is so finely polished that those teeth are as small as possible, this isn't for sharpness as the teeth actually make the edge sharper, the fine edge is for edge retention, the smaller those teeth the harder it is for them to get bent or chipped.

    The type and quality of your steel directly affects how hard it is to grind and how it retains an edge. There are different qualities of steel. The goal is to achieve a hard steel with high amounts of chromium and carbon. That way, its hard enough to retain an edge, soft enough to take abuse, and resilient to corrosion. There comes a point where you have to trade ability for another, and most knives settle in on a balance that best meets the task they are designed for. It is important to know what steel your dealing with as it will affect your sharpening.

    Different blades have different grinds. Some are Flat ground (my favorite) where the entire knife is the bevel. Others are Hollow ground which is a concave grind near the edge, some are convex so the blade is thick all the way to the edge, others are chisel grind where one side is flat and the other has the ground edge. There are others but these cover 90% of blades. Each grind has it's own merits and should be taken into account, along with blade steel, when sharpening.

    Micro bevel, a lot of blades are micro beveled. Hard use blades and kitchen knives gain a lot of edge strength and retention with a micro bevel. You blade may not perform as you expect if you remove this. This is a higher angle edge on the edge of your knife.

    Pushing on a blade while grinding is a common mistake. Some heavy pressure is commonly used for metal removal when a blade is trashed just to speed up the removal. Using two hands is a common practice so you can control a nice even light pressure on the edge, as well as to help maintain the angle.

    You should know you have created an edge when you developer a wire edge down the length of the blade. You should be able to feel it, or get your nail stuck on it. Remember to stroke both side equally when achieving the edge. On some bad blades you can stroke one side 150 or more times and start to feel the wire, however your edge is no longer balanced. Instead it would have been better to grind both edges down equally. Eventually you will feel the wire edge. This is why many people recommend to count strokes and use a descending scale. If the blade is horrible start high say 20 strokes per side, then10 per side,5,3,1 and so on. if its not bad and just needs a routine sharpening, start low say 10,5,3,1 strokes each side. When you feel the wire edge, your done with the coarser stone. If you can feel the wire edge on a portion of the blade, you want to focus on the other portions of the blade so you don't end up removing to much metal.

    Once the edge is established you try to refine it buy using higher grits. This is where angle technique is important. If you do not maintain your angles, you could be refining the belly of the blade and not the edge, or the tip of the edge at the wrong angle which will blunt it. Angles are affected by blade steel, to soft wont hold a low angle, it is to flexible and will roll over, Hard steel will be much harder to achieve that fine angle but be strong enough to hold it, this is what sets the difference between expensive and cheap knives. Typically softer knives go from 20-25 degrees, harder knives from 12-20. 20 degrees is accepted by everyone I've ever talked to as a standard angle. You can customize your knives with angles you prefer them at. I have a tomato knife at about 12 on a cheap walmart knife. So long as it only hits tomato's its flawless, If i use it on pepers, with the harder seeds, it dulls instantly.

    With a grit of 220 your going to remove a lot more metal then grinding on a piece of 12000. The Grits are the least important part to sharpening your blade. You can shave arm hairs with a kitchen knife ground with a cinder block and polished on a piece of cardboard.

    220-400 For a coarse, fast metal removing this is generally the most misused as people think they need to start here and work up About 10% of my blades start here
    1000-1200 is a great general purpose stone and about 70 percent of all my sharpening starts here.
    2k-4k range, This is a great spot for normal home use especially in conjunction with a 1k. This will not actually polish your edge but you'll notice the edge start to have a smoother less scratchy look. This is also a great place to spend time on the flat section to get rid of scratches and leave it with a dull even surface. Then progress higher if you want a mirror finish on a knife.I encourage people to practice polishing the flats of the blade, undoubtedly at some point you will scrap and scratch them, and being able to restore them, and an old knife is very satisfying.
    6k-12k These are polishing the edge. That is still metal removal at a degree small enough to start to mirror your metal.
    10k and up are for high polishing. This is where you make your blade a perfect mirror. This is for fine edges that you can shave multiple hair strings off of a strand of hair.
    Strop's and compounds are really in this same level, 12k-20k

    The starting grit and progression are all about ease of metal removal. Just because you have a 220 or 1k grit doesn't mean you should use it. I bit of experience will help you to learn what grit to start removing metal. Some times a simple polish on a strop removes enough metal to keep a blade sharp. Ask most straight edgers what they do to keep their razors sharp. Razor strops shouldn't be used for knive blades, they have no backing and are designed for a convex style edge. You can dull an edge on a se razor strop if you use it incorrectly.

    Most importantly, experience is king when grinding. Find yourself some stones, or a granite block and wet sanding paper, and garbage knife, and gain experience.
  10. Is a micro bevel the same as a double bevel, like a 15/20?
    Although the bevel I made with a 15 degree angle is fairly small. I don't know how easy it would be to
    put another bevel on it. Any suggestions?
    Should I raise a burr with each level of sharpening stone; how do I remove it ?

    Thanks for the advice
    Last edited: Oct 13, 2010
  11. Yup, thats exactly what I was talking about.

    At low grits on a damaged knife, so much metal needs to be ground that the burr can be easily felt and seen. As you move up in grits the burr is finer and finer, as the amounts of metal being ground are less. For me usually on my 3-4k grit I am no longer concerned with the burr. On a fine surface, the edge begins to polish. Your removing the scratches on the edge caused by the coarser stone. You still have a burr but it changes from side to side with each stroke getting finer and finer. On fine stones you should really be going one for one with the strokes, and trying to slice a thin slice of the stone off.

    Some kitchen knives don't go past a 1 or 2k stone. The knife is plenty sharp, so chef's will steel the blade. That just knocks the burr off, but I recommend people who don't sharpen shouldn't use a steel. They end up ruining the edge they just made, thinking they are sharpening it. Others will run the edge of the blade down a piece of wood, that will take off the burr as well and not damage the edge by holding the wrong angle on the steel.

    As for the micro bevel, if you have a proper 15 degree edge and want to put 20 on the tip, it is really easy. All the work is done if the 15 is proper. You just need to make a couple of passes on a finer stone at the the 20 degree angle. It feels weird because you just spent so much time trying to maintain an even 15 degree angle, now all of a sudden your going the opposite way, but its just a couple quick passes, because the edge is so fine. Again its important to decide what the knife is for. You might want to leave the 15 on it if your cutting veggies deboned meat/fish/poultry. If your planning on doing more of a chopping as opposed to slicing, then that micro will give you longer edge retention.
  12. I am a butcher so I use knives everyday...and sharpen them everyday. The grit you need to start at is determined my your current edge. Are there dings and nicks? When sharpening at the proper angle (which is determined by the purpose of the knife...cleaver vs filet) are you actually sharpening the edge or are you hitting the shoulder of the edge? If your hitting the shoulder or there are nicks in the blade you want to start on a courser stone.

    I use a norton tri hone. If I need it I start on the coarse crystalon (only about once every 3 months!), then medium crystalon and off to the fine india. Depending on what I use the knife for depends where I go from there. On my breaking knife (used to cut primal cuts of meat or even break a side down) I hit my POLISHED steel 50 times. If you have a steel with lines cut into it don't use it at home as there is no need for it. The polished steel burnishes the edge and smoothes it out some, but I want a little bit of bite left in the blade...a little tooth if you will.

    My boning knife I finish on a ceramic steel until it feels right. I have no idea how many strokes but I can feel it start sliding easier and I know I am done.

    Filet knife I actually totally dull when I get them and only sharpen one side...Japanese style. It makes it ride nice against the skin of the fish. I finish it on a spyderco ultra fine bench stone.

    All my knives are Forschner. Inexspensive dependable good quality steel but nothing to look at. If you have a super exspensive kitchen knife please ignore my advice as I have no idea how you should be sharpening them.
  13. Thanks everyone for the help. I managed to sharpen one knife. Got it up to 1000. At least now I can cut with it. I'll have to work on the Edelstahl knives now.
  14. Suzuki

    Suzuki Moderator Emeritus

    I do not profess to be an expert at sharpening - but I agree that, for most people and most knives, stopping at 1,000 is perfectly adequate. I have a ceramic rod sharpener that I use to smooth and maintain the edge of several of my knives and I think its between 6,000 and 8,000 in terms of grit.

    Even for Japanese knives, where some folks advocate going to 16,000 or above, you could get a perfectly good edge off of the 1,000 - although with the harder steel, going above 1,000 will give you an ultra sharp knife, but there are limits to what you will actually notice after 4,000 or 8,000 (FYI, some guys finish straight razors on 8,000 grit stones - so if 8,000 can give you an edge sharp enough to shave with, it can give you an edge that's more than sharp enough to cut tomatoes with).

    If you're just starting out with sharpening, I would forget about the micro bevel stuff - its hard enough to learn to freehand sharpen a single bevel edge.

    Put another way, if you can't get a usable edge off of a 1,000 stone, a higher grit stone won't help you.

    If anything, I think having a 1,000 and a coarser stone (say around 500 - 600) is better than having a 1,000 and a higher grit stone in terms of a starting set up. While you can do everything on a 1,000, I see a lot of guys who have knives with bevels that need lots of work (say for example a knife they've never sharpened freehand before) who get frustrated trying to establish a bevel on the 1,000 stone and start using too much pressure/poor technique out of frustration, which is a sure-fire recipe to screw things up. Having a slightly coarser stone allows you to quickly remove metal so that you can establish a bevel quickly -that being said, too coarse a stone in inexpert hands can transform your chef's knife into a paring knife...
    Last edited: Oct 22, 2010

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