This review consists of :
Ad copy from Tools From Japan :
Bester brand ceramic stones have an enviable reputation of sharpening quickly, but without the dishing that can occur due to their impressive hardness and the strong binding material that makes up the stone. Only available in the lower end of the grit scale, they are widely considered to be one of the best for rapid sharpening of all types of steel.
Note the images, both are of the Bester, however one of them shows a very open surface, very porous the other shows a very closed surface where the abrasive looks masked by the binder. The only difference is that the Bester was lightly used in the second image (far left). This is why stones should be either lightly lapped or used a little before evaluating their cutting / finishing ability as the surface is often not indicative of the rest of the stone.
This is a soak stone, if water is just sprayed on the surface it will soak into the body of the stone instantly. Ater 45 minutes of complete submersion the stone still bubbles. It takes over an hour for the Bester to be fully saturated. Note that the Bester doesn't have the extensive warnings about over soaking and the general strong conditions on use that are commonly present in many modern waterstones in regards to being left in water or dried too fast.
This stone has been left to soak over night on multiple occasions. It has been dried fairly fast (20+ C in direct sunlight) and shows no signs of cracking. This may be due to the nature of its bond which is refered to as "ceramic" vs the resin bond of many other stones such as the Naniwa Superstone series.
This is referred to as a 700 grit stone which corresponds to approximately 22 microns 1 .
The Bester, like many higher end stones can be used straight out of the box with no preparation.
It has to be soaked, and as noted in the above the soaking takes quite some time before the stone will stay wet in use, but it requires no other preparation.
The only concern or note to be made is that initially, as with many stones, the surface can be a little slick. Often times these stones are sealed and therefore the initial grinding can be a bit smooth until that wears away and then the true surface of the stone is revealed. A little lapping can do this, but it happens almost immediately in sharpening, a few dozen passes .
As a quick first trial, the Bester was used to reset the edge on a very basic stainless steel knife which had the apex worn completely off and the bevel was fully rounded over. This is a common state for heavily used kitchen knives which often come into contact with plates, are used to scrap pans and cut up moderate bones, chicken legs and such.
With just 150 passes per side the edge was cleanly apexed. The stone is thus fairly coarse which isn't surprising as that is how it is described. It seems easily coarse enough to remove light damage and readily restore heavily used edges. However it is significantly slower than much more coarse stones such as the Sigma Power 120 which could do the same work in 10-20 passes. Again, not surprising considering the relative grit levels.
A few quick observations :
The way that it wears and forms a slurry is very different than the typical "muddy" stones like the King. It forms a slurry but it is very coarse and produces the same scratchy type pattern as the abrasive itself. It doesn't change in how it grinds as the slurry builds up, however the King and similar stones like the Naniwa Superstone do change significantly as the slurry which is silt like, builds up.
The formation of a significant burr when over ground is also typical of hard stones which do not form that thick mud/silt like slurry to grind into the apex and remove the burr.
Use on a few more knives :
These knives were not only fairly dull, but also needed shaping/material removal to change the edge angle and/or thin the steel behind the bevel. It becomes obvious quickly that while this stone does cut significantly faster than say King 1000 a more coarse stone still would be desired to efficiently regrind/reshape most knives.
Now of course now all knives are made from high carbide/very hard steels, on simple steels the Bester can reset an edge in a short amount of time. As a quick check the ESEE-3 (1095 55-57 HRC) was reground from 14.5 dps to 9.5 dps with 500 pps on the Bester. Now this can be made much faster still with a more coarse stone (Sigma Power 120 is several times as fast).
Some more fairly blunt knives (could not slice photocopy paper well) but with no damage, some needed reshaping.
ZB786
Sprint Delica
Wave Delica
Coyote Meadow
Safari Skinner
Bushman
Another large set of knives, again no visible edge damage, just really heavily blunted. The Bester works well here easily brining the edges to an apex though in general it tends to create a significant burr unless minimization techniques are used. However there is another point which starts to become evident in use on such knives :
On such steels which are fairly easy to grind, then the breaking down of the Bester is a bit wasteful as such steels are easily cut without rapid wear of the abrasive. On inspensive knives, a simple oil stone like the India is a much more efficient choice long term as it has a much higher g-ratio, or grinding efficiency. On the really easy to grind steels the rate of build up of the mud is very high which may be because the abrasive digs in far deeper and thus has a greater chance of being tore out.
As a few quick comparison for cutting speed, the Bester 700 was compared to a Sigma Power Select-II 1000X, one of the fastest cutting stones. A couple of knives were zero ground removing small edge bevels :
In short, both appear to be similar in cutting speed and are in well agreement with the general description of both stones. The SPS-II appears to be slightly faster but cutting speed is directly proportional to pressure and small differences as noted in the above could just be due to random variations in applied load.
Compared to an xx-coarse stone, a TASK garden stone, regrinding an Elmax blade the Bester was significantly slower :
The Bester is about six times slower, but it is about six times as fine so that would be expected. The TASK is so coarse it will take visible pieces out of the edge if is brought to an apex so it is for rough shaping/grinding only.
To examine the finish produced, a base surface was needed to allow ease of examining the scratch pattern. A 1095 blade, a standard #1260 Mora was prepared to a near mirror surface :
This left the knife with a highly reflective surface, near mirror. As the surface is so smooth then it shows any scratch pattern very well. The #1260 Mora was chosen simply because it is so easy to polish as it has a low volume of carbides, no alloy carbides and in the Mora it is typically only moderately hard 59/60 HRC.
The Bester produces the expected fairly harsh scratch pattern, in comparison to the Naniwa Superstone 400 used as a reference. The Naniwa puts on a hazy finish, which looks almost peened under magnification. Even though they are similar in grit (the Naniwa is slightly more coarse at 400X), they produce very different finishes.
The reason for the contrast in the grinding pattern is simply due to the way that the Naniwa Superstone will generate a slurry which is uniformly thick and doesn't settle and is like fine silt. In contrast the Bester forms a slurry which is like sand in water and it maintains that harsh/scratchy grinding pattern.
This makes a significant difference in sharpening as the stones tend to be optimal for different tasks :
Now it is possible to get a fairly clean and sharp apex off of the Bester by using various sharpening techniques to minimize the burr :
However it is much more natural/easier with muddy stones to set the edge for the final micro-bevel. While the images on the right look similar at first glance, if looked at carefully then the burr/damage can be seen on the apex line of the edge which was not formed under various burr minimization techniques. This difference does significant effect the edge retention as the damage (which is the nature of a burr, just damaged steel) extends beyond the burr into the steel and that lowers the durability/edge retention.
Similar there are ways using various techniques to get very clean/crisp edges off of the Bester just as there are to minimize the formation of a burr. In this case it is not just manipulation of the honing passes but also the surface of the stone has to be manipulated to produce the required properties to create such an edge/apex.
The edges on the right was formed with the Bester on Elmax and 121-REX
using a modified sharpening technique,
hone-to-dry. This means the following procedure was used :
This allows the stone to act similar to a very hard stone like the Norton
India and produce a decent apex sharpness. However it has to be considered
that such very hard stones which don't naturally form a slurry will produce
this kind of apex without any special technique/experience.
The Bester is fairly robust in terms of contamination during grinding and
is often used for some fairly harsh work which would/could be consider abusive
to other stones.
As one example it it commonly used to restore/cleanup very
rusty wood working tools such as chisels. Now it does get loaded with rust
during the initial grinding, however
adequate water flushing the stone will keep it cutting well
and the rust will gradually be flushed off with the slurry.
In regards to general wear, this is a semi-hard stone, much harder than
true soft resin bond stones like the King waterstones, but much softer than
say a Norton India or Crystolon stone.
The harder nature of this stone does
have a significant influence not only in how it wears and the pressure/steel
combination for optimal use, but it also restricts how it is flattened.
Now it isn't necessary to buy/use specific purpose flattening stones,
however some of the methods which can be used to flatten softer stones will
not work well, or at all in some cases on the Bester. Now this is off set to
some extent by the reduced wear and thus less frequent lapping however it does
require a little specialized equipment.
Soft stones like the Kings or the Brico can be easily flattened
against concrete or granite or just use fine sand (mainly quartz) on glass.
As the bond of the stone is weak on those stones, even common rough surfaces
can easily grind those stones down to flat even if they have a visible hollow.
However the Bester is far too hard for that to work. The
Bester will just fractures at the edges, and the face just loads
with the rock/sand.
Now in regards to how long it takes to put a hollow in the stone, this is
dependent on :
To minimize wear then the pressure should just be used which allows the
stone to cut and the grinding pattern should be randomized around the stone to
prevent localized wear (Murray Carter has wrote/spoke about this at length).
In general, over a wide range of steels,
after around 10000 passes there would be enough wear in the Bester to warrant
it to be flattened. This would not be a visible large hollow, but just enough
wear that the small non-flat sections would
add enough curvature to increase
the sharpening angle.
To flatten it effectively, as a direct solution, it was at times flattened
against glass using silicon carbide lapping compound, 36 grit is ideal in
terms of cutting speed. However even 90-120X will flatten the stone in
50-100 short passes (4-6" ). In most cases however it was just flattened
against other coarse stones (or even fine ones) and thus essentially two tasks
were combined at ones.
Care has to be taken in flattening stones against each other to randomize
the pattern to prevent one stone cutting the inverse pattern into the other
stone.
The Bester can be used to grind very hard and high carbide steels. It has
been used to even grind 121-REX at 69/70 HRC which is a transition steel
between HSS and solid carbide. It has an extreme amount of even ultra hard MC
type tungsten and vanadium carbide.
However as steels move beyond D2 and up to the high vanadium
carbide steels then the pressure required to allow it to cut well starts to
increase to the point that it puts heavy strain on the edge and apex. These
high pressures can cause the apex to start to crack and these fractures will
significant influence the sharpening process.
Note in the images the apex is fracturing at a level far beyond the
scratch pattern. These are two fairly high carbide, and specifically high
vanadium carbide steels (3V and S35VN) and for those types of steels the
Bester isn't the most efficient choice. Other stones such as the SPS-II water
stones cut such steels with lighter pressure and produce an edge with less
fracture and minimal burr.
This extra roughness will make much more work required if the edge is
brought to a finer finish as that edge has a roughness similar to a much more
coarse stone but the Bester doesn't have that cutting speed and thus there is
efficiency lost on multiple counts.
On the opposite end of the spectrum, use of the Bester on relatively soft
and low carbide steels, then the stone can wear rapidly as the abrasive gets
torn out vs being worn. In order to compensate for this then two things can be
done to limit the rate of slurry formation and ensure that the abrasive is
wearing :
In this manner, even fairly basic steels like the O1 knife at the right can
be ground with very minimal wastage of the stone/abrasive. Note there is very
little abrasive cleaned off on the towel showing a high g-ratio, or grinding
efficiency of the abrasive where it is cutting vs just getting torn out.
Overview :
It is a fairly durable semi-coarse stone, works well to sharpen very dull
knives and with a bit of modification to technique can be used to finish and
grind various steels with a range of carbide and hardness levels.
Comments can be emailed to Please Use the Forum or by posting to the following thread :
and/or the YouTube Playlist for Abrasives/Sharpening.
Most of the pictures in the above are in the PhotoBucket
album.
1
: Conversion Chart Abrasives - Grit Sizes
Maintenance and Flattening
Steel suitability
Overview
Comments and references
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Originally written: 09/09/2013