Nature/natural stones VS synthetic stones

Kevin-B

Kevin-B

Joined
Jun 30, 2017
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442
So I’m fairly new to free hand sharpening. I have always used a worksharp precision adjust. Recently I decided to try out free hand sharpening. So i bought a set of synthetic stones that go from 2000g/3000g/5000g/8000g. Im still learning how to master those. But reading and watching videos about free hand sharpening, i see alot of nature stones.

My question is: is there really a big difference between synthetic stones and natural stones?

Should i as a beginner free hand sharpener purchase natural stones?

And while we’re at it… water stones or oil stones?

Thanks!
 
In my experience, those are quite fine stones you have bought, so you could certainly look at purchasing some natural stones that are coarser. Particulary if you are sharpening a 'regular' knife steel (AUS8, 1095 etc) and not some high end PM steel.
I have tried both Japanese King stones (I know these are 'synthetic') with water used as lubricant and Arkansas stones with oil used as lubricant and prefer an oil stone. It is quicker to get into action, rather than having to soak to prepare for use.
Arkansas stones usually come in 'hard' or 'soft' rather than a specific grit.
I like the Arkansas stones, there is a subtly different 'feel' to them and they would be great stone to develop with from the outset.
 
Ruari said:
In my experience, those are quite fine stones you have bought, so you could certainly look at purchasing some natural stones that are coarser. Particulary if you are sharpening a 'regular' knife steel (AUS8, 1095 etc) and not some high end PM steel.
I have tried both Japanese King stones (I know these are 'synthetic') with water used as lubricant and Arkansas stones with oil used as lubricant and prefer an oil stone. It is quicker to get into action, rather than having to soak to prepare for use.
Arkansas stones usually come in 'hard' or 'soft' rather than a specific grit.
I like the Arkansas stones, there is a subtly different 'feel' to them and they would be great stone to develop with from the outset.
Click to expand...
Thanks for your reply!

The water stones that i have now are indeed a bit on the high grid side. I might purchase some more coarser ones. At for the preparation of the water stones, i dont mind soaking them for a few minutes.

The only reason why i’m interested in nature stones is that i see alot of experienced people use them. They seem way fancier then synthetic stones.

But on the other hand…i’m still a beginner and my synthetic stones get the job done. I can achieve a shaving sharp edge with them. The edge holds up fairly well aswell. So i’m happy.
 
The grit in synthetic stones will be nearly 2.5X - 3X as hard or harder as the grit in any natural stone, such as the novaculite grit in Arkansas stones. That's the defining difference - and it means natural stones won't be able to efficiently cut the carbides in wear-resistant steels. Natural stones' grit is only slightly harder than basic hardened cutlery steel itself, even without all those hard carbides. So, natural stones can work OK or pretty well with simple steels like 1095, CV and low-alloy stainless like 420HC. But they'll struggle with anything very wear-resistant.

The cutoff threshold for me, in using natural stones or not, is with a steel like 440C, which will be difficult to grind or shape very much with a natural stone. For 440C and beyond, I'll use a synthetic stone instead.
 
Obsessed with Edges said:
The grit in synthetic stones will be nearly 2.5X - 3X as hard or harder as the grit in any natural stone, such as the novaculite grit in Arkansas stones. That's the defining difference - and it means natural stones won't be able to efficiently cut the carbides in wear-resistant steels. Natural stones' grit is only slightly harder than basic hardened cutlery steel itself, even without all those hard carbides. So, natural stones can work OK or pretty well with simple steels like 1095, CV and low-alloy stainless like 420HC. But they'll struggle with anything very wear-resistant.

The cutoff threshold for me, in using natural stones or not, is with a steel like 440C, which will be difficult to grind or shape very much with a natural stone. For 440C and beyond, I'll use a synthetic stone instead.
Click to expand...
Hey thanks for you replay and explanation,

I never realized that natural stones are softer then the synthetic one's.
I'll stick to my synthetic stones.
 
I have used a US made norton india stone for years, coarse/fine combo for most of my sharpening needs.
 
No question about it, modern synthetic stones are much more consistent, predictable and controlled in grit than natural stones. That being said, there are some terrible synthetic stones out there too.

Yes, you could get lucky and find fairly good natural stone, but it's better to go with good synthetic stones. You're very likely to get a dud if you buy a natural stone from someone else, because they will generally sell the ones that don't perform well.

As far as buying a natural stone from a store, you also won't really know what you're getting because it is, after all, a natural product with it's expected inconsistencies. With a good set of quality synthetic stones, you know exactly what you're getting.
 
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I have used a natural oil stone in the past but I was never happy with the mess or the fact it dished over time. I now use Spyderco ceramic benchstones and I hve been very happy with them. I also use a Sharpmaker and a Worksharp KO edition with great success.
 
The values listed below are what form the basis of my preferences, regarding which abrasives will work best with which steel types. Ideally, you want to choose an abrasive hard enough to efficiently cut, shape and polish the hardest of any of the components in a given steel or alloy, for the best results. This means that steels containing a significant percentage of vanadium carbides will best be handled by CBN or diamond. Steels with a significant portion of chromium carbides would best be handled with AlOx, SiC, CBN or diamond. And very simple plain carbon or low-alloy stainless steels should do OK with most any abrasive type, including the novaculite found in Arkansas stones.

This isn't to say that some synthetics, like AlOx or SiC, can't be effective at all on steels with hard carbides. It's just that most of the cutting of those steels by lesser abrasives will be cutting of the matrix steel itself, while the carbides will essentially be scooped out by the abrasive grains and otherwise left less refined or unrefined altogether. The difference will be noticed more as the finishing grit becomes finer/smaller, as it'll then start to struggle in doing anything with the carbides in the steel itself.

Relative hardness of popular and commonly found abrasives (Knoop scale):
Diamond: 7000 Knoop (hardest of all)
CBN (cubic boron nitride): 4500 Knoop
SiC (silicon carbide, 'carborundum'): 2600 Knoop
AlOx (aluminum oxide, 'corundum', Al203): 2100 Knoop
Novaculite (in Arkansas stones): 825 Knoop

Relative hardness of components of cutlery steel and it's carbides (Knoop scale):
Vanadium carbide (VC): 2800 Knoop
Tungsten carbide (WC): ~ same as, or slightly less hard than AlOx @ ~ 2100 Knoop or so
Chromium carbide: ~ 1700 Knoop
Iron carbide (cementite): ~ 1100 Knoop +/-
Steel @ HRC 65: ~ 850 Knoop +/-
Steel @ HRC 55: ~ 630 Knoop +/-
 
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Obsessed with edges, What is your usual way to sharpen , freehand or any other method. Thanks
 
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