Maintaining Cutting Tools
- Hello, everyone!
My name is Dr. Jonathan Campbell, and I am the Extension Meat Specialist at Penn State University.
Today we will discuss a topic which, to a lot of folks, may seem very difficult to understand, and some maybe already know how to do this, but we will discuss the topic of knife sharpening.
And so we're going to sharpen a lot of different types of knives, and discuss the different tools used to sharpen knives.
Not every knife is the same, and you cannot sharpen serrated knives, or those knives that have the teeth on them, in this manner.
These are only for straight-blade knives, that we will discuss.
But as I said, not all knives are created equal.
Different knives are used for different tools.
For example, some have a straight blade on them, and if we look more closely...
this blade has quite a bit of flex to it.
I can bend it against a hard surface.
So this may be good for something like filleting a fish, or cutting a piece of meat that may be hard or difficult to get to, and you need a smaller surface.
This blade is about six inches in length, but if you notice, compared to the last knife, it has a little bit of curve to it.
And I prefer this type of knife, when making a lot of cuts around a bone or a lot of more technical cuts.
So this knife has just a little bit of flex to it.
It's not quite as flexible as the previous fillet knife that I showed you.
The next knife we will discuss is about eight inches in length, and it is called a breaking knife.
A breaking knife has quite a longer blade, and is quite stiff in comparison to the two previous knives, with just a little bit of curve that we see in the knife blade.
This knife would be used for exactly what the name implies.
It breaks apart larger cuts of meat, before we go to maybe cut a steak or a roast off of an animal...
We also utilize sharpening steels.
These sharpening steels may be made of quite a different array of material, and also may be coarse in their texture, or fine in their texture.
This is a stainless sharpening steel, made of a stainless rod, and has both coarse and fine.
If we look more closely, as we zoom in on this shaft of this steel, we notice that one side has ridges, or more coarse appearance, and this would be used for repairing maybe nicks in a blade, or for repairing parts of the knife that may have some more severe damage than just others...
On the other side of this steel is more of a fine, or a straight, shaft.
It does not have the ridges that the opposite side here has.
And so I would use this for daily maintenance of a sharp knife.
A lot of people have misconceptions about steels, and we'll talk about some of those misconceptions after we get to the sharpening stone...
In order to physically sharpen a knife, we must be able to grind away some of the metal that we looks on the knife edge itself.
If we were to look at this knife edge underneath a microscope, we would see small, microscopic teeth.
And these teeth, as we hit a cutting table or a cutting board, or a piece of bone or metal, or something like that, get out of line.
And so the sharpening steel is simply used to realign these microscopic teeth that are part of a sharpened knife blade.
When these teeth break off or become severely damaged and no longer able to be realigned with a sharpening steel, we must then sharpen our knife blade on a sharpening stone.
Now, there are a lot of different devices that you can purchase.
This simple sharpening stone, as we see, has three different sharpening stones on it of different types of grit.
One would be a coarse grit...
A medium grit...
Or a very fine grit.
And depending on how dull our knives are, would determine which sharpening stone that we start with.
Now, as you may see if we look closer, these sharpening stones are lubricated with a white oil.
Make sure that you're using an approved honing oil, or look at your manufacturer's suggestions for what type of oil you should be using when lubricating these stones.
This lubrication helps to reduce the friction when grinding away part of the metal from that knife.
If we take our knife and start it at an appropriate angle, about 22 degrees...
We generally start at the butt, or the back of the knife, and work our way across, down to the tip of the knife.
Turn it over, and do the same across that way...
Once we make about three or four strokes across...
We can then begin to feel the edge of the knife very gently, being careful not to cut our hands, and see if we feel any burrs that are developing on the outside of the knife.
Once we have some sharpness or burrs develop on the outside of the knife, we can them move to a more finer stone, or a medium stone, depending on which stone that we started with.
Some of these stones that you can purchase may be what are called diamond-plated stones, and it really has a sheet of metal across the stone with a diamond pattern.
A lot of folks that sharpen knives on a regular basis prefer these to a more basic, wet stone or wet sharpening stone.
Once we get that knife to the consistency that we want, again, more technical work or fine cutting work requires a much finer blade.
Finer blades may not last as long, or stay as sharp, depending on what type of activity that you're doing.
So make sure that your knife matches the appropriate cutting activity that you're doing.
Never try to saw with a blade that is straight like this.
You make sure when you cut, that you cut in smooth strokes and in a consistent of motion away from your body, and away from your non-cutting hand.
So after we get our knife sharpened at the appropriate angle, keeping in mind that the angle could be anywhere between 20 and 25 degrees, as I said, that the correct angle for most knives is around 22 degrees.
We can then build up some burrs, or edges, that we can feel on the outside of the knife.
And that is where our sharpening stone, excuse me, our sharpening steel, comes into play.
We can finish our knife-sharpening skills by utilizing the stone to work away those burrs and edges that may be on the knife blade itself.
Now, you may have seen people that may be trying to show off for a group, or cooking for a group, that really use a steel inappropriately or think they're actually sharpening the knife with a steel.
This is, in fact, incorrect, and the knife sharpening steel should only be used to help realign those microscopic teeth that are on the edge blade that I discussed previously.
So if you notice, the sharpening steel has these edges or flanges, around the steel itself.
That is really for a thumb guard, to protect our thumb as we run the knife blade down the edge of the steel.
So if I put my thumb behind that knife guard, or blade guard, and hold the sharpening steel at about a 45 degree angle to my body, I can then begin to work those burrs and edges to finish off the sharpening job that I did by utilizing the sharpening stone.
I will start again by using the butt of the knife, at the tip of the steel, and slowly work my way down both sides until I get the consistency that I want...
As I said, many people think that they can just-- (knife scraping against metal)
That act does absolutely nothing to help sharpen your knife, in fact, could, in fact, damage the blade.
Some folks are not comfortable with this position of a sharpening steel and fear they may cut their hands.
This is a real risk.
So, to prevent this, you may be able to stand the sharpening steel or honing steel on its edge, and utilize an appropriate, about approximately 22 degree angle, to again work from the butt of the knife to the tip on both sides of the knife, until you get the sharpness that you desire...
This has been a quick reference of how to accurately sharpen knives, and a short discussion of the different knives available that may be used in different types of meat cutting.
So now that we have shown you, and demonstrated various ways to sharpen knives, and different types of knives, I wanted to talk a little bit about knife care.
Now, we all like to use dishwashers at home.
Maybe not everybody does.
But a straight blade like this should really never be put into the dishwasher.
"Well, that may be counter to food safety, "correct, Dr. Campbell?" No, in fact, this would happen, because of the high heat and temperatures that may be associated with a lot of home dishwashers, can really damage the blade.
Hot, soapy water and good rinsing water, with maybe a little bit of a Clorox solution or anti-microbial solution, may help in keeping your knife clean and sanitary at the same time, without risking damaging the blade by exposing it to the long-term, high heat that a dishwasher may impose.
Dishwashers also use a lot of concentrated chemicals that could also damage the blade and discolor the blade, which is not good for long-term blade use.
Most good knives are not very cheap to begin with, so you want to protect that investment.
I also wanted to discuss other options for keeping a consistent angle on a blade.
For those of you that may have trouble keeping that consistent angle, either on the sharpening stone or with the sharpening steel that we discussed, there are several brands of-- There are several brands that can be used to help keep a consistent angle.
For example, the Lansky sharpeners, the Smith sharpeners, and also one that I use quite frequently, is the Edge Pro.
All three of these types of devices help to keep a consistent angle that you can choose which angle that you want on your blade, and keep that consistent angle while sharpening.
These tools may be as cheap as $50, or as expensive as $500.
It really depends on what type of investment that you would like to put into your knife sharpening skills and tools that you have available to yourself.
There are also automatic sharpeners that require the use of electric volts or plug-ins.
These type of sharpeners also do a good job at keeping a consistent angle on the blade, and grinding away that metal.
So that's it for our knife discussion.
I hope you've enjoyed this video.
Frequently Asked Questions