Life on the Edge: A Knife Sharpener's Blog

Do Your Knife A Favor

This may be a strange place to begin, but the best thing you can do for your knives is to visit Sharpen While You Shop as infrequently as possible.  You made a substantial investment in your knives and that investment should pay off for decades.  With this in mind it is important to understand the distinction between sharpening a knife and steeling a knife.

When a knife is sharpened some of the metal is removed and, although barely perceivable, the knife shrinks a little.  Even though the machines and techniques we use are designed to remove just enough material to sharpen a knife and no more, the more frequently you sharpen your knives the faster they will disappear.

A sharpening steel, on the other hand, does not remove material.  Think of it as more of a realignment of the edge.  There are those who claim to put a perfect edge on your knife but remember that it only lasts until you use the knife once.  When you use your knife the edge "feathers" out a little bit.  When used correctly the steel will coax those "feathers" back into a straight edge.

I have had great results with this very safe technique and I teach it to anyone who will listen.

First, I have my student hold out their hand out palm up and with my hand I push down very gently with 2 or 3 ounces of pressure.  Press down on your kitchen scale to feel what a light touch this is.  Many people are amazed that this is as hard as you have to hold the knife to the steel but if you think about it these "feathers" are microscopic so it doesn't take a lot of force.  When too much force is applied by the knife to the steel the edge of the knife will roll or fold over.  As you do this back and forth over and over eventually the feathers will fatigue and break off leaving you with more of a saw and less of a knife.  It is possible to do more harm than good with a steel used incorrectly.

Hold the steel like a dagger vertically with the tip on a wooden cutting board.  With the edge facing down and the spine of the knife at a 15 to 20 degree angle from the steel draw the edge of the knife back toward yourself from the heel of the blade to the tip with a downward motion using almost the entire length of the steel.  Then twist your wrist and repeat the procedure at the angle on the other side of the knife.  Alternate back and forth one side of the steel and  then the other 5 or 6 times and that's all it takes.  The exact angle is not as critical as the fact that you need to steel your knife every time you use it!

If this is all too much for you just come visit us at one of the stores and we will be happy to give you a lesson.  Steeling a knife is hard to describe but easy to demonstrate and you will be an expert after a few meals!

Try A Different Strategy

Are you ready for a new set of knives?  Let's talk.

So you're ready for a fresh start and you have your eye on a block of new knives on sale at Macy's.

Stop right there!

Please take a moment to consider how you came to have your current knives.

  • Did you buy a block of knives and if so, why are you thinking about making a change now?
  • Were all the knives in your current block fully utilized or do some just gather dust?
  • Did they have trouble holding an edge, even with frequent steeling?
  • Were they a gift and you had no choice?
  • Have you accumulated dozens of mismatched, ragtag orphans?
  • Did you buy that one knife because all the others were dull and any sharp knife would do?
  • Did you inherit someone else's knives?
  • Are they left over from college?

Would you please consider a different approach?  I would preface the rest of these remarks by saying that for the majority of us it would be hard to justify the marginal benefit in the performance of a knife over a $200 price point.   That said, you can probably get by for the rest of your life with the same 3 well chosen knives but you are going to have to break open your piggy bank.

This time around let's opt for quality and not quantity.  Spend the time to shop exhaustively for the basics:  a chef's knife, paring knife and bread knife.  Your choices may not even be of the same brand.  If there are two cooks in the family you will probably end up with a different set for each of you.  Do not consider price or manufacturer at first.  Go around and literally pick up every knife you come across so you can start to figure out which one feels the best in your hand.  Take notes.  Once you zero in on a couple knives knife it will be time to evaluate them based on manufacturer and price.  Now think about your choice with a long term perspective.  Choose the best knife you can afford.  If that means you only buy a chef's knife for now so be it.  Wait and save up again for the paring knife and then the bread knife.  You are better off waiting and sharpening your existing paring knife a couple times than compromising and settling for less.

Never base a purchasing decision on whether or not the new knife will fit into your old block.  Just get yourself a Kapoosh Universal Block or get some wooden drawer organizers to keep the knives separate and protected. 

Not Too Sharp

Once in a while I get the strange request to "Please sharpen my knife but not too sharp or I'll cut myself."  While I understand how someone could reach this conclusion, just the opposite is true.  When you have become accustomed to using a dull knife for a while you can fall into some bad habits to compensate.  It's only natural to lose respect for a knife after it gets dull.  It happens slowly over a period of time, like the clutter that accumulates in the garage, until one day you finally resolve to do something about it.

Believing that even direct contact with the edge will not result in any injury, it's tempting to get fast and loose with a knife.  Also, most folks are unaware of how much additional downward force they must apply to cut with a dull knife.  Have you ever had a dull knife fail to bite into an onion and slide off in an unpredictable direction?  A knife that does not go where it is pointed is unpredictable and dangerous.

Tips for safe handling of a sharp knife

  • Always assume that a knife is sharp
  • Use the right knife for the job
  • Do not use more force than necessary
  • The knife is either in your hand or in the block
  • Steel your knife after every use

So remember, it may be counterintuitive, but a sharp knife is a safer than a dull knife.


There is no sadder sight than a customer walking up with an expensive knife that has a broken handle. There is nothing I can do for them short of recommending that they send it back to the manufacturer and beg for mercy.  It is cost prohibitive for anyone to replace the handle of a knife short of using duct tape.

Sometimes I see a handle that was accidentally melted on the stove.  Other times I see a wooden handle that has dried out to the point of cracking or warping. 

The most common culprit in the crime is the dishwasher.  While it might be easy to toss the knives in with a load of dirty dishes there isn't a more dastardly act to perpetrate on a knife.  While the temperature in a wash cycle does not come close to endangering the temper of the steel in the knife, the heat will cause some expansion of the rivets or screws that hold the handle to the knife.  It's the repetition of the expansion and contraction over time that works things loose or causes cracks in both wooden and synthetic handles.

While I'm on the subject of dishwashers there are a couple other reasons to keep knives out of them.  Damage to the knife occurs when the edge bangs into other objects.  Also, damage to the wire basket of the dishwasher occurs when the sharp edge of a knife cuts through the nylon covering the wire frame and the exposed metal gets rusty.

The Confession

Is having a dull knife really a sin?

I must look like some kind of priest because people are always coming up to me confessing the sin of having dull knives.  They apologize for how long it has been since their last sharpening and they leave with sharp knives and the best of intentions to never let it happen again.  And we both know how that will end.

The fact is that there comes a point in the life of every knife when it needs a sharpening.  How do you know when that point has been reached?  Here are a few clues...

When the knife hasn't been sharpened since you got as a wedding present

When steeling seems to have no effect

When the tomato refuses to cooperate

When you look at the edge you see a shiny line reflection

When you hear cursing about dull knives coming from the kitchen.

You have to ask yourself if all the guilt, frustration and cursing is worth it when for just a few dollars and a few minutes you can receive absolution.  Either way you are always welcome here.

Comparing Apples and Oranges

What is the main difference between a steel knife and a ceramic knife?

Aside from the obvious difference in their material composition, the greatest contrast between a steel knife and a ceramic knife is how long each holds a sharp edge.  This is primarily a function of the level of hardness.

The hardness of steel is calibrated on the Rockwell Scale, invented by Stanley Rockwell, a New England metallurgist, in 1919.  The particular Rockwell Scale used for knives is the "C" scale.  The test takes less than 10 seconds. A cone shaped diamond is pressed into the steel with about 330 pounds of force.  Then they measure the depth of penetration and one Rockwell number is equal to penetration of 0.0002 millimeters.  So a penetration of 0.12 mm would rate a 60 on the Rockwell Scale.  Most steel knives rate between RC58 and  RC63.

There is nothing like a Rockwell Scale for ceramics so we can compare materials using another scale, the MOHS (Material Order of Hardness Scale of mineral hardness).  This scale was devised in 1812 by German mineralogist Friedrich Moh.  On this scale talc powder rates a 1, a fingernail is 2.5, glass is a 5, quartz is a 7 and a diamond rates a 10.  A white ceramic knife comes in at 8.5 and a black ceramic knife comes in at 9.

By comparison a steel knife comes in at 5.5.  It's the hardness of the ceramic knife that's responsible for it's ability to hold an edge so much longer than a steel knife with a RC63.  The tradeoff for the hardness of a ceramic knife is brittleness.  The ceramic knife is more likely to chip or break when it encounters a bone or gets dropped on the floor.

With the sharpening equipment we use either material can be sharpened easily and quickly.

Recipe For A Great Knife

How do they make steel and ceramic knives?  You can look at making a knife like a recipe in terms of ingredients, temperature and cooking time.  

Let's start with a steel knife.  There are literally thousands of combinations of ingredients in various proportions that one can choose from.  My favorite American steel manufacturer is the Crucible Steel Company out of Syracuse, New York.  Their CPM (Crucible Particle Metallurgy) process is specifically designed for knife steel.  You can read about their unique process here.  Steel is the combination of iron and carbon.  Crucible adds these alloys to the iron for their CPM S35VN knife steel in these proportions... 

Carbon 1.4% (hardens the steel)

Chromium 14% (stain resistance)

Vanadium 3.0% (strength for holding an edge)

Molybdenum 2% (wear resistance for edge retention)

Niobium 0.5% (wear resistance for edge retention)

This is all forged at 2100 degrees, annealed at 1650 degrees and double tempered at 600 degrees with a freezing treatment between tempers.

Ceramic knives are a different story and Kyocera makes the best .  Unlike steel, ceramic knives have one basic recipe.  With 330 tons of pressure zirconium oxide powder, is compressed into the shape of a knife.  A black blade is made out of a black zirconium oxide and offers extra durability. This type of blade goes through an extra firing process called a "hot-isostatic press" for 2 days at over 4000 degrees creating a tighter weave between the ceramic molecules, thus creating a tougher blade. The white ceramic blade is made out of white zirconium oxide and is kilned at 1200 degrees but does not go through this expensive sintering process.

The Most Common Question

If there is a question I get asked most frequently it is "When you sharpen my knife how long will it last?" This is a tough one because there are a few variables and that makes it sound like I am avoiding the question.

The first and largest factor is the steel recipe used when the knife was created.  There are literally hundreds and hundreds of possible combinations of elements that a manufacturer can choose from and is impossible to tell anything from just looking at the knife.  For this reason, before you purchase a knife, it is imperative that you are familiar with the name and reputation of the manufacturer.  But since the customer is usually asking about a knife they already own this point is moot.

The next variable addresses the frequency of use.  Most folks say they use their knives four or five times a week.

The type of cutting board is the next factor and there is none kinder to the cutting edge of a knife than wood.  There are basically two different views on cutting boards:  wood versus plastic.  Those favoring plastic will concede that it is harder on knives than wood but, more importantly, it can be put through a dishwasher.  The way I see it, since you should be hand washing a knife with warm soapy water after every use anyway, why not wash off the wooden cutting board at the same time.

Finally, there is the frequency of steeling.  Whether you choose to steal your knife before or after you use it makes no difference.  The fact that you steel your knife every time you use it is the single biggest factor you control in the equation.  And the best time to start and continue this new habit is immediately after a sharpening.

So the answer to the question is...

Probably 3 or 4 times a year.  This might seem like a lot more often than you are accustomed to but once you experience a sharp knife you will immediately develop a very low tolerance for dull knives. Most folks have tolerated dull knives for so long that they can't even remember what a pleasure it is to prepare a meal with sharp cutlery.  Please come by and treat yourself to a sharp knife soon!


Solar Powered Sharpening

Jeff, the founder of Sharpen While You Shop found inspiration for this project came from his fellow knife sharpener and mentor, Terry Beech, and his company SharpQuick.  Terry has a completely restored 1969 VW van, including wiring for solar panels integrated into the electrical system of the van and sharing a single battery.  This seemed like a great idea because as knife sharpeners we work on location outside all day. 

I took a slightly different approach and permanently installed the solar panel on top of my vehicle.  I ran the wires through the body of the car to a controller module.  This critical piece of the puzzle keeps the solar panel, battery and inverter working in concert with each other.  In my stand alone system the solar panel feeds the battery which feeds the inverter that powers my machinery.  I ran the wires from the inverter out to the back end of the car where I installed a standard household outlet for the extension cord to my machines.  On an average day the system generates about 5 amps.  Beside the obvious savings on gas and generator wear and tear, the solar arrangement has turned out to be a great conversation piece.

Stop by and check it out.  And if you would like more details I would be happy to give you a list of the components, prices and where each was purchased.

Good Deed For The Day

Have you ever wondered what to do with an old knife you were ready to discard?

Just drop it off with us and we'll get it re-purposed!  For example, in San Jose we take them with us to the local homeless shelter when we sharpen their knives.  The Emergency Housing Consortium or EHC prepares about 450 meals every day and knives in the kitchen are frequently "lost" for one reason or another.  Over the years they have amassed an amazing variety of cutlery and your contribution would be greatly appreciated.  

If you don't have a knife to donate they can always use a gift card from Costco or a supermarket.  A card like that gives them some discretion in supplementing their needs when the large donations of food they regularly receive leave gaps in the menu.


Have Questions for Sharpen While You Shop?

Call 408.891.0225 or email

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