Pro-Pack II Ceramic Stone Question

[Geocyclist]

Please correct me if I am wrong, I am definitely not an expert here.

Grit size is the size of crystals (or cutting media), which should indicate the depth of scratches it would leave. I don’t know how rigid the standards are for grit rating, much less the quality control of different stone makers. Highly controlled stones would have all grit exactly the same size, other ones may have a higher variation grit sizes where the average grit size is what is listed.

There is more to stone media and their performance that just grit size. There are other factors, which I am still trying to learn. Such as aggressiveness, etc. Given equal grit sizes different types of media will cut, polish, etc. differently.

[wickededge]

Please correct me if I am wrong, I am definitely not an expert here.

Grit size is the size of crystals (or cutting media), which should indicate the depth of scratches it would leave. I don’t know how rigid the standards are for grit rating, much less the quality control of different stone makers. Highly controlled stones would have all grit exactly the same size, other ones may have a higher variation grit sizes where the average grit size is what is listed.

There is more to stone media and their performance that just grit size. There are other factors, which I am still trying to learn. Such as aggressiveness, etc. Given equal grit sizes different types of media will cut, polish, etc. differently.

Abrasives is a very big field of study. In addition to the size of the grit, there is hardness, friability, density, substrate or matrix and probably a few others that all affect sharpening.

-Clay

[Phil Pasteur]

http://www.foodieforums.com/vbulletin/showthread.php?11502-Natural-Stones-and-other-abrasives-(are-grits-just-grits-)

Check that discussion out.
I found it while trying to find something that Scott posted that was more of an article on the physical properties of abrasives, the one qabove seems to be more results oriented.

Phil

[Joel Fiorentini]

Phil, That was very interesting reading. Thank you.

[wickededge]

That was very entertaining reading and it brought up some good points, not the least of which is that getting the framing of a complex question right is crucial. In hindsight, it’s easy to see that they were almost always talking about different things. On one hand it was: Everything else being equal, do different stones confer a performance benefit to identical knives? On the other hand it was: Do those stones produce different results? Underlying all of the valuable discussion there was the very interesting question of if specific abrasives impact performance when all the other variables are the same. Another way of framing it could be “Would an equal density of equally sized but different abrasives applied at the same angle and pressure give two identical knives the same or different cutting performance?” I think the answer is a qualified ‘Different.’ Some abrasives are friable and will create smaller teeth than the original as they break down while others are not friable and don’t break down so they will cut teeth closer in size to the original grit. Some abrasives are harder and will cut deeper scratches and give a toothier edge. Some abrasives have different shapes and, while they may all fit through the same sieve, the will cut deeper or shallower scratches. The ‘Different’ is qualified because you could probably test for and observe performance differences that would correlate to the measurements of the micro-teeth if you had extremely sensitive and highly accurate testing apparatus and methods, but the huge majority of users would probably not notice much difference in actual cutting applications. In the end it’s mostly hypothetical because there aren’t really good examples of stones of different abrasives with otherwise identical formulations and characteristics. A lot of Ken’s arguments about the experience of different stones and their effects on the bevel were true too. In the Wicked Edge line-up, you can get to much the same place via the different accessories available though your experience can be very different. The Choseras area a good example of how using different stones are a truly different experience. Depending on how much importance you place on Process vs Results, you might select a specific lineup of accessories. There are good arguments to be made for selecting your stones and strops based on kind of edge you’re looking for given the intended use of the knife and your aesthetic preferences.

-Clay

[wickededge]

That was very entertaining reading and it brought up some good points, not the least of which is that getting the framing of a complex question right is crucial. In hindsight, it’s easy to see that they were almost always talking about different things. On one hand it was: Everything else being equal, do different stones confer a performance benefit to identical knives? On the other hand it was: Do those stones produce different results? Underlying all of the valuable discussion there was the very interesting question of if specific abrasives impact performance when all the other variables are the same. Another way of framing it could be “Would an equal density of equally sized but different abrasives applied at the same angle and pressure give two identical knives the same or different cutting performance?” I think the answer is a qualified ‘Different.’ Some abrasives are friable and will create smaller teeth than the original grit size as they break down, while others are not friable and don’t break down, so they will cut teeth closer in size to the original grit. Some abrasives are harder and will cut deeper scratches and give a toothier edge. Some abrasives have different shapes and, while they may all fit through the same sieve, once bonded in the stone their orientation will cause them to cut deeper or shallower scratches. The ‘Different’ is qualified because you could probably test for and observe performance differences that would correlate to the measurements of the micro-teeth if you had extremely sensitive and highly accurate testing apparatus and methods, but the huge majority of users would probably not notice much difference in actual cutting applications. In the end it’s mostly hypothetical because there aren’t really good examples of stones of different abrasives with otherwise identical formulations and characteristics. A lot of Ken’s arguments about the experience of different stones and their effects on the bevel were true too. In the Wicked Edge line-up, you can get to much the same place via the many different accessories available, though your experience can be very different. The Choseras area a good example of how using different stones are a truly different experience. Depending on how much importance you place on Process vs Results, you might select a specific lineup of accessories. There are also good arguments to be made for selecting your stones and strops based on kind of edge you’re looking for given the intended use of the knife and your aesthetic preferences.

-Clay

[Fred Hermann]

Yes and yes.
A brief story…
Dad and I used to do serious coast to coast road trips.
As a side trip we stopped off at AGRussel in Arkansas. Dad bought me a fairly expensive ultrafine Arkansas stone. Of course I dropped it and broke off about a third of it. I was devistated, and dad got me a replacement. Same batch, same shelf.
The replacement was much rougher. I still have them and I’d guess there is at least 100grit difference.
So inconsistancy in abrasives isn’t new, but it’s interesting there’s so many standards considering the fine industrial uses.

[Author]

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