Look sharp!

April 16, 2009 5:16 PM

I'd like to sharpen my knives and pruner, but how?

Sharpening: why is it so expensive? Is this a super complex skill to learn? What are the basics I need to know about how to sharpen, and what are the essential tools I need to make things sharp? (A recent trip to the fancy Japanese tool store revealed about 25 different sharpening implements ranging in price from 20 to 100 bucks each!) Should I leave sharpening to the experts - or is this something I would be an expert on had I been a boyscout? Give me your sharpening wisdom here!

posted by serazin to technology (26 answers total)

It's not a complex skill, but it's difficult to explain and easy to do wrong. If you do it wrong, repairing the damage you do to a knife can be pretty time-consuming. It's best learned with a coach watching over your shoulder, pointing out mistakes you wouldn't otherwise realize you're making.

I do all of my sharpening with flat stones, so I can't comment much on the various doodads and gizmos intended to make it more foolproof.
posted by jon1270 at 5:30 PM on April 16, 2009

Learning the basics of sharpening is not very hard. But learning to do it without shortening the lives of your knives and tools significantly is a very difficult skill.

This is a generally good tutorial on how to sharpen tools, as is this for knives.

To do any more than a half assed job, you will need at LEAST two double sided synthetic, different grit stones. That is, you want one stone that is coarse/medium coarse grit (very low number / lower number), and another which is medium fine/fine grit (high number / VERY HIGH number). You move from lowest number to highest, as you sharpen, starting with usually the higher grit side of your coarse stone (reserving the lowest grit for really horrible work, like removing rust or pits). If you are picky, like me, you'll eventually get where you have 8-10 different natural stones, which all have different grits, and which you use a different combination on depending on the tool or knife. But I'm a steel snob.

This wikipedia page is actually a pretty good overview of the various types of sharpening stones. You will also need a sharpening steel, if you want to have your edge hold for any real length of time. For a good overview of everything that goes into it, I suggest this page.

I personally prefer natural oil stones to whetstones, but that is because they help cut down on flakes of metal and stone getting everywhere as you work. I have used a Japanese waterstone in the past, and really, they are superior in my experience in producing an edge, but they are so expensive and wear out so fast that I now reserve them for my VERY good knives. I also personally stay the heck away from diamond ANYTHING when sharpening, as I find it takes too much steel off whatever I am working on unless I am very careful. YMMV on that though.
posted by strixus at 5:33 PM on April 16, 2009

If you can find an industrial sharpening business near you, you may be able to get your stuff sharpened for cheap. I go to a guy who sharpens things like massive cutting tools for the car industry and he "charges" me $3 per knife (I'm a chef - and I hate sharpening my own knives). Only, he's never actually taken money from me! I've gone to him for five years now.
posted by cooker girl at 5:36 PM on April 16, 2009

To sharpen a knife, you need a sharpening steel - basically a piece of steel that is harder than the knife, with a handle attached. Nothing more. As with most purchases of everything, the middle of the price range will serve you well.

Sharpening is much easier to learn if you get someone to show you - it may be time to make friends with a chef or a butcher. If you are right handed, the knife will be in your left hand with the edge facing to the left and the steel will be held in your right hand. You draw the steel along the knife blade at about a 30 degree angle to the edge, doing a stroke to the top then a stroke to the bottom, alway drawing the steel away from you. Try to keep the same pressure on the steel for the full stroke. Your left hand will turn back and forth slightly for each stroke as you switch the steel from the top side of the blade to the bottom.

For scissors, shears and pruners, you will need an oilstone. I found this book really useful for learning how to do this.
posted by girlgenius at 5:39 PM on April 16, 2009

I'm guessing you went to Hida Tools? That places is awesome, but looking at sharpeners there is completely overwhelming. :) At any rate, pruner cutting blades are sharpened at a 23 degree angle, and then the burrs cleaned off the back. Don't mess with the anvil blade. It's nice to get a small stone that doesn't require you to take the clippers apart; Felco has one for 20 bucks that is perfectly fine.
It also really helps to keep your clippers (pruners) relentlessly clean. I usually clean the blade of mine with rubbing alcohol because it does a good job removing sap. Cleaning before sharpening is a good thing, becuase it keeps the stone from being gummed up.
posted by oneirodynia at 5:50 PM on April 16, 2009

To sharpen a knife, you need a sharpening steel - basically a piece of steel that is harder than the knife, with a handle attached.

This is not the case. You are describing a sharpening steel, which is not actually used to sharpen a blade, but to hone it, straightening out the edge of the blade which bends flat and develops burrs with use (and misuse). This will serve you well for some time, but there comes a point in every blade's life when it is too dulled or damaged to hone, and the edge needs to be sharpened, or re-ground. This cannot be done with a steel.
posted by dersins at 6:01 PM on April 16, 2009 [4 favorites]

Seconding dersins re: sharpening vs. honing, and cooker girl re: getting someone else to do it. I take my knives to a guy here who charges $3 per knife and does it while you wait. I'd rather pay him a few bucks a knife a few times a year than ruin an expensive knife trying to do it myself.
posted by sanko at 6:06 PM on April 16, 2009

Around where I live, I know you can take your knives to the local supermarket (Big Y) and they'll do it for you (ask at the butcher counter). YMMV.
posted by reptile at 6:09 PM on April 16, 2009

Seconding dersins here. Using a steel alone on your blades will DESTROY them. Please don't.
posted by strixus at 6:57 PM on April 16, 2009

I'm not sure if this will really clarify anything, but it might help to realize that sharpening is basically just a precise abrading away of metal to create a crisp new edge. Oilstones, waterstones, ceramic and diamond sharpening stones are hard, microscopically rough materials which grind metal that's rubbed on it. That's all they do. Maybe it's obvious, but I remember being mystified by all of the terminology that gets tossed around -- honing, stropping, steels...

Butcher's steels do not abrade away metal and can't restore a badly worn edge, but they can extend the useful life of a good edge, so people call using a steel "sharpening," even though the purpose it serves is very different from that served by abrasives. "Honing" may refer to using a butcher's steel, or may refer to abrasive sharpening, depending on who's talking.

There are also many ways to get the job done. For some people (like Strixus, above) sharpening takes on a sort of ceremonial importance. It might be soul-satisfying to have a drawerful of stones, but you can put your knives in the 99th percentile of sharpness with, oh, maybe 2 different grits.

Since you're interested, you might as well get a stone or two and start sharpening a couple of your less-valuable knives. Let a pro handle your fancier tools until you gain confidence. This is definitely a skill that requires a lot of practice to do well, not one you can quickly master by watching a YouTube video. It's more like playing the violin than installing a hard drive.
posted by jon1270 at 7:39 PM on April 16, 2009

I use a Wusthof 2 Stage Knife Sharpener on all my kitchen knives, my crappy Target specials and my better than average Henckels. I've sharpened them all to a dangerous, "Look I can skin a tomato or cut through a soda can" level of sharpness.
posted by MasonDixon at 7:49 PM on April 16, 2009

I bought a cheap electric stone wheel sharpener that uses water as a coolant/lubricant for the blade being sharpened. I found it very easy to use, pretty effortless, and does a great job. Sometimes too good. The water keeps the blade cooled so that it doesn't heat up and affect the hardness. Does knives, scissors, etc.
posted by Taurid at 8:10 PM on April 16, 2009

Silicon carbide wet or dry sand paper stuck with glue to any flat surface, slab of glass, makes an excellent sharpening system.
posted by hortense at 8:16 PM on April 16, 2009

Don't over complicate things. Sharpening edged tools is not that complex, it just takes a little care and practice. There are lots of instructional guides available. Is your pruner an orchard/shrub pruner? Speaking from many years of orchard fruit tree and general gardening I recommend a small, fine triagular file. If it's a by-pass type pruner just touch up the flat side of the blade with a few careful strokes with the file flat against the blade. Then a few easy passes following the angle of the manufacturers grinding on the curved side of the blade should do it. Clean the cutting edges with a lightly oiled piece of fine steel wool before you put it away - carefully so you don't cut yourself.

I used a two sided, course/fine, flat round axe stone to sharpen everything for years. The blades of my knives, axes and Pulaski could shave hair; but that degree of sharpness isn't necessary and may be counter productive.
posted by X4ster at 8:21 PM on April 16, 2009 [1 favorite]

When researching this topic a few years ago, I found this page to be very helpful, particularly the careful descriptions of different edges. It's in six parts - it's pretty exhaustive - including sharpening basics, sharpening step-by-step, an overview of sharpening systems, and resources.

I use a whetstone for my old Japanese carbon steel knife but get my other knives professionally sharpened. At a buck per inch of blade, it's worth the trip. Plus, hanging out at the knife store and looking at the merchandise is kid-in-a-candy-store time.
posted by goofyfoot at 8:34 PM on April 16, 2009

my 2 cents: I have started sharpening all my plain-edge knives with very fine sandpaper and a steel to finish the edge. If I show these knives to a tomato, it slices itself. 'nuff said. Buy some crappy old knives and practice on those first to get a consistent angle and stroke. A crappy dull knife sucks, but a 'classic' razor-sharp knife is a great gift to a new home-owner (gotta get a penny for it, though).
posted by flowerofhighrank at 11:57 PM on April 16, 2009

"To do any more than a half assed job, you will need at LEAST two double sided synthetic, different grit stones."

Utter nonsense. Elitist, tool-fetishizing nonsense. I can sharpen household scissors with a single stone (synthetic or natural) as sharp as new. I've sharpened knives on a rock I found in 30 seconds of searching at a campsite; the result wouldn't suffice for brain surgery, but it made the knife plenty sharp for campsite cook prep.

Seconding everyone above who said it isn't hard, isn't expensive, but requires a guiding hand to teach you the basic "feel" of the task.

Or you can stumble along through lots of crappy attempts until you self-teach, as I did. Given the chance to do over, I'd go with the first option.
posted by IAmBroom at 7:30 AM on April 17, 2009

Well, despite the somewhat contradictory advice, I think this is an excellent start. I'll report back after I've tried sharpening a few things.
posted by serazin at 8:27 AM on April 17, 2009

Since you're an Oaktown person, I'll note that there's a dude at the Berkeley Farmers' Market on Saturdays that does knife-sharpening for cheap. I've figured it's easier to give him $5-$10 to sharpen a knife than to try to learn to do it well myself.
posted by Zed at 8:36 AM on April 17, 2009

Here's an excellent (and very detailed piece) that should complement Stixus' links nicely: Knife Maintenance and Sharpening, Instructor: Chad Ward (Chad)
posted by awenner at 8:54 AM on April 17, 2009

Adding to the question - do the sharpening experts here know if there's an effective difference in brands of sharpening stones? Lee Valley's stones are a lot cheaper than Global's.
posted by awenner at 8:59 AM on April 17, 2009

Also, the Sur La Table on Maiden Lane is doing free knife sharpening through the month of April....
posted by Arthur Dent at 10:43 AM on April 17, 2009

It might be "Elitist, tool-fetishizing nonsense" IAmBroom, but my knives and other blades will be around by far longer than yours will. And will not need to be sharpened nearly as frequently.

I look forward to my grand children getting knives that I have had since my teens, just as I got a knife from my grandfather that he had had nearly as long.
posted by strixus at 1:19 PM on April 17, 2009

FWIW: Sur La Table in L.A. chewed-up two of my knives so badly last year, they are still recovering from missing chunks. DIY: get some knives and practice. When they can slice a sheet of typing paper, it's good enough.
posted by flowerofhighrank at 10:16 PM on April 18, 2009

I made a guide to keep the bevel even. slice a wine cork lengthwise I cut slightly off center and place it over the back of the blade I use the small side of the cork to create the back bevel until the burr comes up then I switch the cork around and hone the smaller second bevel final edge using the large side of the cork.
posted by hortense at 11:37 PM on April 18, 2009

If you just want your knives to not suck, have them sharpened. But if you want to learn, I would have to recommend the John Juranitch book The Razor Edge Book of Sharpening. The guy that wrote it apparently shaves his face with an axe. I'm not affiliated with them.

I shave with a straight razor whose edge I maintain myself. Most of what I know about edges came from this book, plus some practice. You don't need a mentor at your shoulder, or exceptional perseverance, just pay attention.

X4ster is right on. If you have an edge with a completely flat face (a scissor or a bypass pruner), do NOT sharpen that face at an angle to the abrasive. Unless some schmuck before you did, in which case go play in traffic.

I don't go in for the gizmos myself, but I do know the carbide ones you just draw the knife across remove more material than they should and do not provide a durable edge.

You don't need a million stones, but a range of abrasives (including diamond) used judiciously can cut down the time you spend. OTOH, the judicious part comes from time spent in attentive practice. There's no such thing as a free lunch.

Seconding flower's advice. A dull Global or Sanelli doesn't cut any better than a dull whatever from the dollar store. Once I learned and got up some confidence, I sharpened our average quality kitchen knives a year ago.

Steeling them 3-6 strokes every few uses, I have yet to abrade again---and my wonderful wife cooks a lot. Get a steel made of steel, not a diamond "steel", because the steel's purpose is to preserve the edge by straightening it NOT by removing material from it. That's why the angle isn't so critical when steeling.

I'm a mechanic, so working metal is familiar to me, but still I had to learn before I could sharpen. If you're not a mechanic, sharpening edges is a great introduction to that realm. It requires very little technical knowledge or equipment, but you get the satisfaction that comes of mastering a manual process. Good for the soul.

One more thing---there's all kinds of guide apparatus available. My dad bought the razor edge guy's guide, and for really fine work you need a guide. My straight razor's spine is an angle guide by design, and for that edge it's the only one to use. But in general, teaching your fingers to do right is a good investment.
posted by maniabug at 4:34 PM on September 15, 2009