Waterstone testing part IV; how flat is ‘flat’?

Hello again faithful reader, and there really ARE a lot of you out there now!

This is somewhat of a re-cap on things, but it’s a pertinent question that really needs to be answered thoroughly.

While the purists might be able to keep a stone very flat through working it’s entire surface evenly (I can do it, but I’m not a purist!), most waterstone users just can’t quite manage it, so the ability for the allegedly friable, “easily dished,” waterstone to remain flat during use is important, from a conventional users standpoint at least.

This is something that the ‘stone consumption’ comparison touched on in Part I but didn’t completely address; as that it only pointed out how much of each stone was ‘used up’ in each stage of testing. Granted, it was measured by returning each stone to a dead flat, usable level after each test, and measuring how much stone had to go down the drain to get there. But remaining ‘flat’ is not merely a measure of how much stone gets used up. It’s a little more complicated than that.

You see, every stone here is different. They are made with different materials, abrasives, and methods of manufacture.

Take the King Deluxe; it’s a classic baked clay/abrasive mix. As such, it’s very soft and very inexpensive. On the opposite end of the scale, you have something like the Sigma Power Select II with no binder (which is simply abrasive sintered (high heat and pressure) into a single block) and is expensive. You have kiln fired ceramic stones, such as the Sigma Power Hard and Bester, with their highly resistant and tough binders. The Shapton Glass Stone appears to be a high quality abrasive suspended in a plastic-like materials. The Naniwa Superstones also appear to be composed of plastic-like materials. The Arashiyama is a combination of natural and synthetic abrasives in a durable yet friable binder.

All these stones, all getting about the same kind of business in vastly different ways, lately the desire has been to develop a stone, or stones, that works quickly, yet stays flat!

And flat is not something that can be easily measured, but it can be evaluated through observation.

By taking a careful look at what the final finish (after the #5000 Naniwa Superstone) on the blade looks like, and by keeping the finish stone as flat as possible, we can see where the blade might not be as flat as it should be.

Because sharpening/honing was stopped while using the finer stone, we are able to see what’s going on before the blade is made flat by the finishing stone.

And, as fortune would have it, a test for ‘dish resistance’ was included in the testing regime, being part of the ‘white steel chisel torture test!‘

All of the other steels tested were finished off after each stone with 20 half stone length strokes, no more, no less with the final finish on the bevel evaluated and recorded by photograph. However, during the white steel test, the finishing stone was required to polish the bevel all the way to the edge, but ONLY to the edge. By taking a record of how much of the entire bevel was actually polished as soon as the polish reached the very edge, a reasonable estimate can be made of how flat the previous stone stayed. By recording the number of strokes to achieve that ‘polished edge’, we can also quantify numerically how flat the previous stone stayed because the only variable in the test was how the bevel was left by the previous stone.

While we are here, we can also quantify how much stone was ‘used up’ by this test, to see how little dish in a stone can affect things and how much ‘dishing’ occurred. This is a calculated figure, and should not be taken as a rule, only a guide.

The presentation of this will be by alphabetical order, with a picture of the bevel as it was finished by the stone, followed by a picture of the bevel after the #5000 stone had done its work. The number of strokes done by the #5000 stone, width of polish at the edge and approximate area and condition of bevel polish and will also be mentioned. These finer details may not show up in pictures as well as I would like, so the commentary is essential.

So, stone by stone, let us see what transpired…

Arashiyama #1000

Number of #5000 strokes: 10.

Amount of stone consumed: 0.04mm

Width of edge polish: Full.

Condition of bevel: Only polished at the very tip. Many obvious yet fine scratches.

Bester #1000

Number of #5000 strokes: 10.

Amount of stone consumed: 0.045mm

Width of edge polish: Full.

Condition of bevel: Only polished at the tip, very clean. Minimal amounts of very fine lines in the hard steel.

King Deluxe #1000

Number of #5000 strokes: 65.

Amount of stone consumed: 0.113636364mm

Width of edge polish: ¼ of the edge.

Condition of bevel: Only the very middle of the bevel is polished, although it is polished to from top to tip. Where polished, very clean but an obviously and chronically rounded bevel.

King Hyper Hard #1000

Number of #5000 strokes: 10.

Amount of stone consumed: 0.076923077mm

Width of edge polish: ½ of the edge.

Condition of bevel: Only the very tip is polished, and of that only the middle area with many fine scratches. Some dishing but not too serious.

King Neo #800

Photographs missing…

Number of #5000 strokes: 30.

Amount of stone consumed: 0.219230769mm

Width of edge polish: ½ of the edge.

Condition of bevel: Only the middle section of the bevel is polished, showing signs of significant dishing. Some fine scratches in the polished area.

Naniwa Chosera #1000

Number of #5000 strokes: 10.

Amount of stone consumed: 0.04754717mm

Width of edge polish: ¾ of the edge.

Condition of bevel: Many small lines, blotchy polish possibly caused by clogging.

Naniwa Super Stone #1000

Number of #5000 strokes: 10.

Amount of stone consumed: 0.066666667mm

Width of edge polish: ½ of the edge.

Condition of bevel: Blotchy polish, middle area only. Some signs of dishing but not severe.

Norton #1000

Number of #5000 strokes; 10.

Amount of stone consumed: 0.0375mm

Width of edge polish: ¾ of the edge.

Condition of bevel: Only polished at the tip, many scratches, and generally poor.

Shapton Glass Stone #1000

Number of #5000 strokes: 10.

Amount of stone consumed: 0.06mm

Width of edge polish: Full.

Condition of bevel: Full width, but shallow depth of polish. No lines, very good.

Shapton Professional #1000 (Japanese Edition/Kuromaku)

Number of #5000 strokes: 10.

Amount of stone consumed: 0.011428571mm

Width of edge polish: Full.

Condition of bevel: Full width deep polish, very few tiny lines, but otherwise very good. Signs of polishing and clogging developed from the #1000 stone.

Shapton Professional #1000 (US edition)

Number of #5000 strokes: 10.

Amount of stone consumed: 0.017142857mm

Width of edge polish: Full.

Condition of bevel: Width deep polish, more tiny lines than Japanese edition, but otherwise very good.

(Note; this was the only test where the two Shapton Pro stones differed significantly, but in such a way that their places may be reversed if tried again.)

Sigma Power Ceramic Hard #1000

Number of #5000 strokes: 10.

Amount of stone consumed: 0.031818182mm

Width of edge polish: Full.

Condition of bevel: Full width deep polish, no discernable lines. Signs of polish developing from the #1000 stone, but no signs of clogging on the stone or tell tales on the bevel.

Sigma Power Oribest #1000

Number of #5000 strokes: 80.

Amount of stone consumed: 0.1725mm

Width of edge polish: ½ of the edge.

Condition of bevel: Many lines, some scratches. Shows signs of dishing along the length of the stone but not across its width. Bevel is polished from top of the blade to the tip.

Sigma Power Select II #1000

Number of #5000 strokes: 15.

Amount of stone consumed: 0.2mm

Width of edge polish: ¾ of the edge.

Condition of bevel: Inconclusive. Large lines in the polish, which is only at the tip and ¾ wide. However, the blade was ‘over sharpened’ and had a massive burr/wire edge on the back side. With fewer sharpening strokes, the follow up should have been faster/better.

So, what can we take away from this? We have a bunch of results, some showing obvious signs of dishing, some showing absolutely no signs of dishing and the amount of stone used not really reflecting the results found, so how about we compare the amount of stone used with the observations of dishing on the bevel?

So, what does this bunch of squiggly lines actually represent?

The blue line is the amount of stone ‘used up’ during the white steel test. The stones are ranked from left to right on how much of themselves they gave up in the quest for knowledge.

The red line is the number of follow up strokes on the #5000 Naniwa Superstone to get the polish to the edge.

The green line is how broad the polish on the bevel was once it touched the very edge (represented as a percentage).

Now, the blue line goes up, as you’d expect it to. What’s interesting is not on the left half of the graph when looking at the green line, but what’s happening on the right side of the graph. From the left, the green line is very predictable. Blue goes up only slowly, green stays right up there, reflecting that the amount of stone consumed for those stones was low, and that naturally the level of dishing on the stone/rounding of the bevel was also low. The small deviation up there isn’t something you’d notice in day to day sharpening, so on the left, yes these stones “stay flat”.

As the graph shows, it is obvious that using up more stone translates into dishing and bevel rounding, until you hit the very end of the graph with the Sigma Select II and King Neo. These two stones had a significant amount of their life taken away (actually less than a percentage point, but still significant!) but not that much dishing evident. In the case of the Sigma, actually very little dishing was observed, and if these stones were graded on observed bevel rounding, they would be much closer to the left side of the graph.

Why?

Simple, the Sigma Select II and King Neo are intended for very tough, abrasion resistant steels, such as High Speed Steel (HSS) and Stainless Steel (SS) respectively. Because the white steel chisel did not offer a challenge to them, they got the job done incredibly quickly, before they could dish to a significant degree. So while they may feel soft, and are comparatively soft, they might not be able to effectively resist dishing ,like the much harder ceramic type stones, but they are able to ward off dishing by getting the job done fast.

Another fly in the ointment is the King Hyper. While it sits solidly on the right side of the graph, the amount of observed dishing and follow up strokes is quite low. Why is that? Again, there’s a logical explanation.

The King Hyper is made of similar stuff as the hard, ceramic stones but in a softer binder so it does ‘spend’ itself to get the work done quickly. However, because the abrasive is quite tough and high quality, what’s being shed and left on the stone is still working very hard and not ‘spent’ as it might be if the abrasive used was less durable. So while the stone itself might be dished, the slurry is doing just as much as the abrasive still on the stone. A curious observation, and while it might not sound so impressive here and now, the implications are very interesting, especially for some of you out there reading this.

The King Deluxe lives up to its reputation of being soft and easily dished. No surprise there. The Sigma Oribest however fared very poorly, and the reason is that it’s of the same intention as the King Neo and Sigma Select II, but the binder is soft, maybe a little too soft. This does help it deal with very tough, hard steels but when pushed beyond its limits, it can’t keep up. A good stone if you need something that will work with tough steel, just don’t push it too hard, it will bite back.

If you prefer a stone that “will not dish,” stick to the stones on left side of the graph. If you prefer to get things done quickly, stick to the stones on the right. If none of this is important to you, throw a dart and pick the one it lands on.

Thanks again for reading,

Stu.