I’m new to the sharpening game and have learned a lot in the last few months. But - I haven’t yet internalized even the major concepts. I think I understand the difference between grits when talking about sandpaper. A 60 grit paper would have about 60 abrasive particles per square inch? But I’m having difficulty understanding the difference between oil stone and water stone grits. For example, I have an old Norton Tri-Stone oil stone system (IM313) that includes a coarse stone (‘coarse crystolon’ - made of silicon carbide), a medium stone (‘medium crystolon’ - also made of silicon carbide) and a fine stone (made of aluminum oxide). The corresponding grits are listed as 100, 150 and 320 respectively. I can’t get my head around the comparative ‘grits’ reported by water stones because a medium water stone sharpening grit is reported to be around 1000, with fine grits moving into the 4K, 5K, 8K and even 10K range. Can someone please help this old geezer with my problem understanding how the grits actually compare - and why there’s a huge discrepancy? Thank you in advance!
Comparative grit question
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Drosophil
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Yet-Another-Dave
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That doesn't sound right, 60 grit is really coarse, but by your definition that would be less than 8 particles by 8 particles in that square inch and that doesn't seem right.
Basically grit isn't very well defined and not all manufacturers carefully follow whichever definition they do "use".
Here is a link I found with a chart showing the relative values of the numbers in some systems:
Grit Size Chart
All you can easily rely on is that the bigger the number the finer the stone is for that brand. Within a type, e.g. water stones, the numbers are relatively close. But given different abrasives and different steel also affect the results from any given stone, you can't really rely on a single number and in practice it's not that big of a deal.
PS- I'd guess your Fine India stone is roughly 1K on the waterstone scale. I've heard from a couple different fans that Hard Arkansas and Washita stones are probably in the 2-3K range, but have a "gentler abrasive" making the result equivalent to a higher grade, maybe 4-6K, synthetic in practice.
[Beaten by Drosophil. Clearly I type too slow / say too much.
]
masibu
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Designated "grit" only tells part of the story as well. A fine india stone is rated 320 grit (or there abouts) however it may or may not grind as quickly as a waterstone depending on the state of the stone. Oilstones wear slowly and if using with minimal pressure the cutting speed of that same fine india stone could be the equivalent of about a 700 grit waterstone if its heavily worn. They can be reconditioned using loose coarse silicon carbide to cut as new (or you can up the force on the stone to release fresh abrasive).
Waterstones wear more quickly but don't require conditioning (generally) but will need general maintenance to retain flatness.
Companies use their own terminology to define what is fine and what isn't. There is little consistency unfortunately and its not always easy to find the information you are after unless you speak to someone who has used a lot of different stones.
Waterstones wear more quickly but don't require conditioning (generally) but will need general maintenance to retain flatness.
Companies use their own terminology to define what is fine and what isn't. There is little consistency unfortunately and its not always easy to find the information you are after unless you speak to someone who has used a lot of different stones.
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A guy on Bladeforums put together a grit chart that’s pretty informative. It’ll give you an idea of how all the different standards and some manufacturers compare. Remember, grit designations on mean some percentage is that actual size, and contains a percentage of coarser grit. https://www.bladeforums.com/threads/the-grand-unified-grit-chart.856708/
Drayquan
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In my experience a 1k silicon carbide will seem more coarse than an aluminum oxide 1k, and both of them will seem more coarse than a ceramic based 1k. However, as stated by others above, there are many variables that could affect this and cause different experiences for others, depending.
I found it pretty amusing to discover the nonsense that manufacturers/retailers of budget range aluminum oxide/corundum stones label their grits as. The cheap stones on Amazon for example (BearMoo, etc) seem to just label the grit whatever they think will be good for marketing purposes/selling to customers who are new to sharpening. They have fairly arbitrary grit labels with little regard for the properly made, equally labelled/graded grit stones they’re .....undercutting (no pun intended! ahem ok maybe a little intended).
It’s not regulated so companies can label their products as whatever grit they want. The good ones are actually scientific and very precise about it, just be weary of grit rating labels on budget range products
I found it pretty amusing to discover the nonsense that manufacturers/retailers of budget range aluminum oxide/corundum stones label their grits as. The cheap stones on Amazon for example (BearMoo, etc) seem to just label the grit whatever they think will be good for marketing purposes/selling to customers who are new to sharpening. They have fairly arbitrary grit labels with little regard for the properly made, equally labelled/graded grit stones they’re .....undercutting (no pun intended! ahem ok maybe a little intended).
It’s not regulated so companies can label their products as whatever grit they want. The good ones are actually scientific and very precise about it, just be weary of grit rating labels on budget range products
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scott.livesey
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grit is defined by grain size. US or ANSI 100 grit is 125 microns. trouble is everyone uses different system. so ansi 100 = j100 = p120(p seems to be european). but ansi 320=j500=p400. so read fine print before buying a stone to make use.
And then there is FEPA-F, which is used for many EDM stones, which is different again.
Not to mention Naniwa's grit system, which seems to be a bit finer than JIS for each particular grit.
Not to mention Naniwa's grit system, which seems to be a bit finer than JIS for each particular grit.
masibu
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The chosera line is a bit coarser isnt it? That's what ive seen on charts and experience at least (its been a while though). The 1k might be slightly higher but the 3k and 5k im not so sure. The superstone line polishes way above the suggested grit though. I havent used their other line of stones to compare to king/bester etc though.
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There's an up to date version on Google Docs here: https://docs.google.com/spreadsheet/ccc?key=0Aj58bmHF7wCtdDg4RjBaOFJhZXI1RHFsM2F4N1JpVGc&usp=sharing
