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Stone grit progression question, please.

Fri Jun 14, 2013 2:03 am

I use the EP, but I think this would be the same question for any stone. I read on the EP forum about jumping from one grit upward to another. It was mentioned that a jump from 1K to 2K GS was double.
Is there an optimum progression on GS's and other stones? What would determine the "best" progression? Would it be better to go from the GS 1K to the 1500 and then to the 2K?

Would it have something to do with what finish (shiny-ness) you were going for?

Thanks.

Re: Stone grit progression question, please.

Fri Jun 14, 2013 5:09 am

RAY <> You determine your "best" progression... from trial & error - experience.

When you're sharpening you're scratching steel with an abrasive which is leaving a pattern... w/"teeth" at the edge. The more you want to refine that pattern... the higher the grit stone. A 1500 will replace a 1k pattern more quickly than a 2K will, but you are effectively replacing one pattern with the next. So in efforts of time efficiency, doubling your grit works efficiently. Sometimes you want more teeth... e.g., using a 5k Rika after a 1200 Bester simply refines the 1200 pattern, aka "teeth", leaving a toothy yet polished edge. I mean if you spend long enough on the Rika, it will replace the 1200 pattern, but that wouldn't be an efficient way to do it if that was your ultimate goal.

If you're goal is to improve on your "shiny-ness", use very light pressure on your last stone and really refine the mud.

Re: Stone grit progression question, please.

Fri Jun 14, 2013 5:16 am

There are many theories/opinions on this matter of "ideal" grit progression.

Yes, IMHO the edge finish would dictate input.

However the fundamental practicality remains - spend enough time on each stone and then the progression jump can get wider apart at the cost of time & effort per stone.

For example, I do a refined 500# edge, then jump to 8k for a few very light strokes on a dash higher angle just to so ever refine the course bite - lovely slicer edge.

A 30k edge has very little merits in my book in terms of practical application (for kitchen use that is).

To achieve mirror bevels stick to close grit jumps - ensure that the previous scratch patterns are smoothed sufficiently, otherwise they tend to "shine" through at the higher polish level.

Strop finishing mirror bevels with loaded leather takes many, many passes per side (like 300 or more) depending on steel type/hardness & compound used, coupled to the finish level of each stone used in the progression.

Then there is the additive of a dash of dish washing soap to aid as a wetting agent - it decreases the surface tension of the water, aiding with less loading of the stone by "floating" the schwarf.

Creating too much mud when doing mirror bevels will cause "scratching" of the shiny surface - use a hard stone with plenty water & clean blade after each pass.

I personally like to double up for normal progression.

It all boils down to personal preference, with the nature/performance characteristics of the stone used, playing a big role.

That was briefly said, as this topic has endless debate potential......

:)

Re: Stone grit progression question, please.

Fri Jun 14, 2013 5:43 am

I'm in the 1.2K to 5K camp Raibeaux. For me it provides just the right edge for kitchen use, which is scary sharp with a touch of bite or tooth. If I went from 1.2K to 3K to 6K for example, I would still be scary sharp, but I would loose the bite I like.

If you are after mirror bevels, then as has been suggested, closer is better.

Re: Stone grit progression question, please.

Fri Jun 14, 2013 3:20 pm

Theoretically, you could work with only the highest grit stone you wanted to end with. It would just take a REALLY long time. :)

The old rule of thumb was to double the grit. 500, 1000, 2000, 4000, 8000, 16000

That's a decent rule of thumb, but as others have noted, it depends on you and what you are after.

That said, GS 1k, to 1500 to 2k is not necessary on any level. That's way overkill.

I jump from 1k to Rika (3 to 4k) and then to 10k. I don't like a refined bite as Branwell described though. I remove all the scratches from 1k at the Rika, and then the same on the 10k.

So, you can take any number of approaches, look for any number of results, etc.

Re: Stone grit progression question, please.

Fri Jun 14, 2013 6:02 pm

As a general guideline, I like to double grits, ie 24 60 120 220 500 1k 2k 4k 8k 16k 32k 64k 128k, etc. Yes those aren't precisely double but you get the general idea.

For very abrasion resistant steels, you could go in even smaller jumps, but for softer steels - eg European knives, much larger jumps are appropriate. In the extreme, going from a 180 bamboo to a 2k stone is not unreasonable for real soft knives, leaving a bit of toothiness in the process. I also go in smaller increments with single bevel knives just because you are abrading more metal.

There is the issue of convenience. For Glassstones or other splash and go level synthetic stones, small jumps are particularly appropriate, whereas if you have to soak a lot of stones from scratch, I would tend to get lazy and use less stones. I am not a big fan of going from a 1k to 6k stone.

Also if you own say a 1k 1500 and 2k stone, you can select which ones you use for a given knife based on the condition of the edge, but using all three is excessive IMO.

For naturals , the spread can be much greater as any given stone can be used to start off coarse and refine itself during the session, so for instance a 3 stone sequence isn't unreasonable, but you can ( and I often do) go with more.

Because part of my work involves evaluating stones as well as sharpening knives, it is rare that any two knives get the same sequence of stones. So for instance, I might triple my jumps 120 320 1k on a softer knife or use a 180 and a 220 in sequence if I find I just need a bit more abrasion from some scratches rather than jump to a 500.

It comes down to experience, preferences, the need to explore, etc. In the end you develop your own guidelines and change them with experience. One of the things I love about the Nubatama series is the ability to fine tune a sequence to your needs, with Shapton and Chocera being a close second and third :)

One oddity does come to mind. I often recommend a 150 bamboo with a 140 Atoma. 10 'points' worth of difference? Why bother? Well because diamonds and waterstones 'scratch' different and you are going to have problems jumping from a 140 Atoma to say a 1k stone, but jumping from a 150 bamboo to a 1k finish is reasonable for a somewhat softer steel. For a harder steel a 400 is a reasonable 'inbetween'.

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Ken

Re: Stone grit progression question, please.

Fri Jun 14, 2013 7:56 pm

Hmm. I think I'll try thinking of it as, instead of removing or abrading metal, I'm scratching it away. Then I'm scratching the scratches away. And use my photo loupe. Maybe I'll get more of an idea of what's going on, unless that's completely weird??

I really do appreciate you folks helping everyone so much.

Re: Stone grit progression question, please.

Fri Jun 14, 2013 7:59 pm

Na, that is the perfect way to look at it!!!

Why do I think that? Cus its what I did :)

Re: Stone grit progression question, please.

Sat Jun 15, 2013 2:07 am

:) Or scratching the metal away between the scratches :) Yea, it's a very reasonable way to think of it all...

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Ken

Re: Stone grit progression question, please.

Mon Jun 17, 2013 4:12 am

It's the silence between the notes that makes the music....


Thanks again.
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