People who are serious about knife sharpening use stones to get that perfect edge. But not everyone agrees on whether or not to use them dry. After several years dealing with cookware warranty claims, I will finally put that debate to rest.
First, let’s talk about different kinds of sharpening stones.
Oil stones, water stones and diamond stones
Oil stones use oil as a lubricant to wash away the waste material produced by sharpening. FUN FACT: This waste is called “swarf.” Oil stones are widely available in both natural and synthetic materials.
- They’re the least expensive
- They rarely require reshaping
- The oil is messy and an ongoing expense
- They are the slowest at sharpening
Water stones use water to wash away they swarf. Although natural material water stones are available, they are hard to find and expensive. Stores usually sell synthetic water stones. The binding material that holds the abrasive sharpening bits together is softer than with oil stones, so the used material washes away quickly.
- Water is cheap, readily available and easy to clean up
- They sharpen quickly
- They require the most maintenance
- Quality controlled water stones are expensive
Diamond stones use industrial diamonds (not mined ones, that would be ridiculous) to sharpen your knives. It’s no secret that diamonds are hard, so re-shaping is not required.
- They sharpen the fastest
- They retain their shape
- They are expensive
- The ones with holes are not recommend for serrated knives (the smooth surface ones are just fine)
Coarseness or “grit”
There’s a variety of grits available. Think of the grits as being like sandpaper. The lower the number, the coarser the grit.
Generally, people use a low number, like 240, to sharpen and higher numbers, like 1000 and above, to “polish” or hone the edge.
Starting with a low number and working up to the high numbers gives you the sharpest edge.
Just like my post on honing, there are a few different ways to position your knife and stone. By practicing a few different techniques, you will find a way that’s comfortable for you.
The important thing to aim for is the angle of the blade. European-style knives should be sharpened at a 22 degree angle. Japanese knives require a 15 degree angle. If you look very closely at the edge of your knife, you will likely see the angle you should be aiming for.
Keeping it still
If your stone didn’t come with a holder, you can fold a tea towel, wet the bottom (the area that will sit on your counter) and place the stone on top. You don’t want to use a ton of force when sharpening, so the tea towel should keep your stone nice and still.
Water stones and oil stones will eventually become bowed or misshapen. You really need a flat surface for proper sharpening.
When you notice your stone starting to warp, you can buy a small reshaping stone and use it to create a nice, flat surface.
And now, the moment you’ve all been waiting for…
Only a diamond stone should be used dry. In fact, you shouldn’t use liquid with diamond stones at all.
Only use oil (like a food grade mineral oil) with an oil stone.
Soak your water stone in water for at least ten minutes before use and keep it thoroughly wet.
But why do you say this with such confidence?
As I mentioned, I dealt with a lot of warranty claims and customer complaints. I know that some websites still say to use stones dry for faster sharpening. Trust me, “But I read on the internet…” is not a viable excuse for a warranty claim. (And no, the irony is not lost on me.)
A customer came in to the store with a sharpening stone that he said wasn’t working anymore. I had never seen anything like it. I didn’t think he bought it from us, but he had the receipt.
I asked him what happened. He told me after a few years of use, it changed colour and just stopped working.
As I inspected it, I saw the maker’s mark of a popular brand we carried. I asked more questions and when he said he never used water, it suddenly made sense.
With nothing to wash away the swarf, the sharpening motion of the knife had polished the stone.
The stone looked like a shiny new marble counter top.
The stone’s instruction manual said to always use water, so it couldn’t be filed as a warranty claim. At about 1/3 the cost of a new stone, I sold him a reshaping stone.
It helped, but that little piece of marble was never quite the same.
For goodness sake, always read the instruction manual, find trusty sources, and learn from others’ experiences.