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Sharpener and Accessory Maintenance

TOPIC: Maintaining Waterstones for use on the Wicked Edge

Re: Maintaining Waterstones for use on the Wicked Edge 2 years 3 months ago #2839

  • mark76
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Thanks again, Ken! Very useful information now more and more stones are becoming available for the WEPS.

What I wonder is why synthetic stones (and natural stones) actually have to be flattened. Or, more precisely, why they degrade/break down. And how they do it. Nearly every stone seems different. Some synthetic stones require soaking and quite a lot of water and slurry to work effectively, some stones (like the Shaptons) require only a little bit of water and the WEPS stock ceramic stones also work dry (although I wonder sometimes whether a little bit of water would not help in keeping them clean). And they all wear down differently. The WEPS stock ceramic stones don’t seem to wear at all.

My guess would be that is has something to do with the bonds in which the abrasive particles are set, but that is about as far as I can guess.
Last Edit: 2 years 3 months ago by mark76.
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Re: Maintaining Waterstones for use on the Wicked Edge 2 years 3 months ago #2842

  • jendeindustries
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A great question, Mark! Here's the tip of the iceberg :lol:

It's not so much that synthetics wear down as much as the abrasives are released from the matrix in the spot on the stone that is used, causing the wear.

For example, the Chosera and Shapton stones for the WEPS generally wear in the middle because that is where you use them most, but not as much on the last 1-2cm of each end. The abrasive is aluminum oxide, which is still pretty hard - a 9+ on the Mohs scale. Rubbing the knife against the stone causes the abrasive to scratch, but there will always be a point where the abrasive either wears down, and/or is dislodged or pulled from the matrix.

The rate of abrasive wear is pretty much determined by the abrasive - Aluminum oxide is harder than your abrasives made from quartz, feldspar, or emery - which are about 5-7 on the Mohs. Diamonds wear the slowest, being a 10 on the Mohs scale. We'll come back to this in a minute for the second part of your answer.

Stone wear is really the rate at which the abrasives are released, and is dependent on the matrix that holds the abrasive in place. The general rule is that softer stones release abrasive faster than harder stones, and coarser stones release abrasives faster than finer stones. The theory behind this to to simply add more abrasive particles into the mix on softer and coarser stones, making them faster. (There are added perks to stones dishing readily, such as creating a convex edge, but that's another topic. We've seen how the concentration of abrasive can speed up or slow down sharpening/polishing on the pastes threads, too). So what happens here is the abrasive that is released does not necessarily break down, but the matrix holding it, does. As you get into the finer points of abrasives, you will find that natural stones' abrasive do break down while synthetics tend not to, depending on the abrasive. For this discussion, let's keep Aluminum Oxide as our synthetic abrasive since it is what the Shaptons and Choseras use, and the WEPS ceramic are probably something in the 9 Mohs range as well.

How porous a stone is also an indicator of how strongly the abrasives are held in place. More porous means more gaps between abrasives and binding agents, thus a faster abrasive releasing/wearing stone. Shaptons, for example, are not porous at all, so they hold the abrasives in place much longer, allowing for the fuller and more perfect scratch potential the aluminum oxide, which takes a while to wear down. IOW, less wear, more action, with no polish since there is little to no matrix breakdown.

Choseras, are what I consider to be slightly porous (compared to many other brands on the market), so they release abrasives at a slightly faster rate then Shaptons, but much slower than other brands. More importantly, the Choseras couple the abrasive release with the polishing effect of the binder breaking down, giving that amazing 10K polished mirror, but under the scope is slightly imperfect due to the inevitable release of the aluminum oxide abrasive particle here and there.

Getting back to the diamonds, since they wear the slowest of all abrasives, they are firmly embedded in a steel plate, with their multifaceted peaks sticking up. Because they wear so slowly, it would be an expensive waste to release them from the matrix, and is why diamonds tend to stay flatter longer - the height of the diamond is measured in microns rather than millimeters. (here's a look at some diamond plates under the scope). They will still "wear" more in the middle than at the ends but the rate is almost imperceptible when you add the overall cutting speed. Any imperfections will easily be cut through at the next diamond plate level.

SO the bottom line here is that you need to lap stones to 1. flatten them. 2. Clean them 3. texture the surface (for abrasive release rate purposes).
:)
Tom Blodgett
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Re: Maintaining Waterstones for use on the Wicked Edge 2 years 3 months ago #2843

  • mark76
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Thanks a real lot Tom! This is very informative!

Do I understand it correctly if I summarize it as follows? (Which was my way of learning at school :).)
  • Stones wear down because 1) the abrasive particles in the stones get worn down (i.e. shattered to pieces or at least scratched off) and because 2) they are released by the matrix bond.
  • Effect 1) is the most important. The amount of wear depends on the hardness of the abrasive, so for example aluminium wears down faster than chromium that wears down faster than boron. (Just googled the Mohr scale <- very informative. Why do they use a different scale - the Rockwell scale - for steels?)
  • Effect 2) depends on:
  • the size of the abrasive particles: course stones wear faster than fine stones, probably because large particles get “hit out” easier
  • the concentration of the abrasive particles: more particles means faster breakdown, probably because there is relatively less binding agent per particle
  • the porousness of the stone, i.e. the gaps between abrasives and binding agents: more porous = larger gaps or more gaps = faster breakdown
  • the strength of the binding agent: steel hardly releases abrasive particles (i.e. hardly wears down), whereas certain resins release the abrasive more easily.
  • The breaking down of the binding agent (rather than the breaking down of abrasives) also causes a stone to polish, in addition to being abrasive. That is why the relative porous Choseras (compared to the Shaptons) polish so well at fine grit sizes.

  • And just trying to draw a conclusion to see whether I understand some things correctly: we can have diamond plates (a single layer - or at least not many layers) like the Wicked Edge diamond stones, comprising diamonds set in a steel plate, because the steel does not or hardly releases the diamonds and because the diamonds hardly wear. If we were to set aluminium oxide in a steel plate, the aluminium would wear down quickly and we were left with an almost clean steel plate. And if we were to set diamonds in a less strong resin, that would be pity of the diamonds that get released while still being intact.

    Wow man, you guys are teaching us a real lot! :woohoo: We can even start to discuss which stones to use for which purposes! (I promise I won't do that - yet :).).

    Very curious to your comments! This weekend my first Choseras will be deflorished :).
    Last Edit: 2 years 3 months ago by mark76.
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    Re: Maintaining Waterstones for use on the Wicked Edge 2 years 3 months ago #2844

    • jendeindustries
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    You're certainly on the right track, Mark! B)

    I would only make one slight "correction", which is to change breakdown to abrasive or particle release rate.
    the porousness of the stone, i.e. the gaps between abrasives and binding agents: more porous = larger gaps or more gaps = faster breakdown

    We are definitely heading toward deeper discussions of "which stones for what purpose". That is where the real fun is - but before you go there, you'll need to begin forming a sharpening philosophy - Otherwise you'll go crazy chasing after each new revelation! :evil:
    Tom Blodgett
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    Re: Maintaining Waterstones for use on the Wicked Edge 2 years 3 months ago #2845

    • mark76
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    Thanks a lot, teacher! :cheer: You should have chosen another job ;).

    Just one thing before I start soaking my Chosera's: what is the use of water on these stones?

    Obviously I have read a bit about it ;). Such as about the difference between slurry and swarf. A slurry is a mixture of water and stone abrasive and may help in polishing/sharpening. A swarf is a mixture of water and metal debris, which inhibits the action of the stones and is therefore undesirable.

    Water helps to create a slurry and remove the swarf. (There is a nice book page on this phenomenon, too, including some controversy as to the use of slurry.)

    However, why do some stones create a slurry whereas others don't? Or: why should Chosera stones be used wet and the Wicked Edge ceramic stones be used dry? (I know these latter stones can be used wet and that soapy water will probably keep them cleaner, but that is not really necessary.)
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    Re: Maintaining Waterstones for use on the Wicked Edge 2 years 3 months ago #2850

    • jendeindustries
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    The primary use of water on stones is for lubrication and for washing off debris. However, as you begin to develop and use the paste (which is an advantageous breakdown of the abrasive mixed with water and metal bits), or mud, the water is used to keep things at a certain "concentration". For example, a popular honing method for straights using a coticule, called the "Dilucot" method, starts off with a heavy slurry concentration and gradually adds water to dilute the concentration, thus slowing down the action so that it polishes more than it cuts, ultimately ending with stone and clean water only. With no lose abrasive, it is the least invasive abrading, which is good for finishing an edge. Most synthetics work on this same premise. (Coticule's abrasive is Garnet, which are about 8-9 on the Mohs, so there is a more similar connection to Aluminum Oxide stones, rather than other natural stones).

    In an odd connection to the Dilucot method, this is also why some stones like the WEPS ceramics are used dry - the texture of the surface of the stone catches the loosened abrasive and metal bits (aka dust), which are generally finer than the grit of the stone, and add more polishing/burnishing. Depending on your sharpening philosophy, you can see that as either "clogging" or "enhancing" the action of the stone. Cleaning them off will make the stone more aggressive again.

    You see Arkansas stones generally promote the use of oil (which I know is your next question!), and that serves the same purpose as water, but I think oil holds the paste/swarf better. In this case, unlike the Aluminum Oxide, you have an abrasive that does like to break down, becoming finer as you use it longer. We all know how well oil attracts dirt and does not readily evaporate, so the trick is to use the same oil paste as long as you can in order to achieve a finer finish than just a clean stone - which is quite the opposite approach!

    Japanese Naturals work the same as Arkansas, but they use the water just as effectively - probably (and this is a gross generalization) because the abrasives break down more readily. Ken can describe in greater detail about the stones with holes (suita?) and without, that are used purposely to catch smaller particles, much like the Ceramic WEPS.

    ....and we have come full circle :silly:
    Tom Blodgett
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