For more information on Sharpening Stones, see our beginner site Common Woodworking.
There is always the challenge of changing someone’s made up mind once the mind is indeed made up or someone has already perhaps invested time and money into something or, even more, taken offence. It’s natural to defend a stance we already agree with, after all. We all do it to some greater or less degree I think. But being close-minded means much effort is often wasted.
By now you should have realised that abrasive is available to us in many different forms and that both abrasive and steel wears away.
The Encyclopaedia Britannica describes abrasive thus:
Abrasive, sharp, hard material used to wear away the surface of softer, less resistant materials. Included within the term are both natural and synthetic substances, ranging from the relatively soft particles used in household cleansers and jeweller’s polish to the hardest known material, the diamond. Abrasives are indispensable to the manufacture of nearly every product made today.
Of course there are then pages describing the substance of abrasive we don’t need at the bench, but what we need to know is that about 95% percent of the abrasives we use in woodworking and sharpening is man made using naturally occurring materials mostly mined and then fired into the bricks we call whetstones or sharpening stones. Some of these stones work best with water and some with oil. Natural stones are generally mined or quarried and then cut to size and graded according to quality, hardness and size. Natural stones were the standard means of sharpening for centuries. Many natural occurrences affect the quality of natural stones and this leads to higher levels of waste material that can then be used to make man-made stones and so minimise waste. Man-made stones have the least waste of all.
What happens at the purchase point results from the decision you make in choosing stones or a sharpening method or system. In fairness to catalog suppliers, the range is massive and the demand great. I would not like the job of categorising and choosing the offering although it is dead simple for me; in the name of the old Bond movie I think, “Diamonds are forever.” I think I have already said this but all abrasive stones cut steel. Because powdered abrasive doesn’t remain in position but as loose particles gets pushed around, most abrasives are formed from particulate into hard blocks and wheels. Some sharpening stones rely on a slurry from the fractured surfaces to further abrade and polish surfaces of steel.
The width of most stones and plates used by woodworkers is between 25-30mm thick by 50-75mm wide and 200-250mm long, but larger stones and plates are made and used. I use 75mm by 200mm (3” by 8”) diamond plates. A favourite addition of mine is a 200mm x 200mm coarse diamond plate for restoration of bevels.
Most bench plane irons are between 50mm and 65mm wide. Up until the recent guru workshops, people held the plane iron in the right or dominant hand so that the iron and hand align comfortably in the arm and with the body squared to the end of the oilstone applied pressure from the greatest advantage point for applying adequate pressure.
Stones today might still be generally categorised under the generic term whetstone but it’s an older term, which simply means sharpening stone. Oilstones are whetstones as are waterstones as are diamond plates. These stones are made up of solid particulate graded according to coarseness except for the diamond plates which are steel based and surface coated with diamond particles in different grades. Diamonds are the hardest of all substances and are the most wear resistant. All other stones start out flat and wear down throughout the sharpening process. This wear forms a curved or hollowed surface. The modern trend is to continually flatten the whole surface of stones and I believe that this is somewhat valid if indeed the stone is hollowing and not just curving. In a previous post I told you that it’s simply a method to combine the use of oval motions with overhanging the long edges of the stones to keep the stones flat across the narrower width throughout sharpening. This is to even out the wear, but this of course is only practical with wider blades such as bench plane irons and wider chisels 1” and up. The long curve, as distinct from hollowed or dished, doesn’t need to be flattened really, but the reason for flattening is mostly the initial ease. You must then figure this into the equation because constant flattening then negates the initial ease.
Do all stones need to be dead flat?
There can be no doubt at all that all stones were worn to curved and/or hollowed surfaces throughout the centuries and millennia. It was not because they couldn’t flatten stones but because for general use there was little need to. It also meant that they knew the necessity to manipulate the steel blades they were honing or grinding to keep stones more evenly shaped or shaped how they wanted them shaping — how they ‘liked’ them. When I used oilstones I did that too, mostly because I liked to stop my stones from hollowing. I would dare to go much further than this and say that in some cases, for curved irons, gouges and such, they relied on curved surfaces customised by their individuality in the same way craftsmen and women through the millennia developed shapes to metals and clays and glass and fabrics by eye and arm movements and could replicate exact shapes over and over with barely any discernible differences. Curved surfaces along the length of a stone still facilitates a good cutting edge without compromise in any way at all, but working with narrower tools such as 1/4”, 3/8” chisels, plough plane irons and such caused gouging and hollows to the stones that they couldn’t just let go because these causes ever-deepening hollows that, left uncorrected, renders a stone unusable for wider plane irons. Now let’s look at hollowed surfaces for a just a minute. I remember one time using a hollowed stone to sharpen my edge on a number 4 1/2 plane iron. After two strokes the man who’s stone I borrowed told me to stop as I was ruining his stone. I was holding the iron at the wrong angle or a different angle from the one he would usually use. When he honed his iron the sound was smooth but when I honed it was more a coarse grating sound. He showed me the angle he honed at, which was more elongated along the length of the stone. This meant that the cutting edge came out with his preferred gentle camber along the edge of the cutting iron. I was 16 years old. I understood then that not all stones needed to be flat. You see, for me, the question is who is it in this generation that demands flatness to every sharpening stone? It wasn’t heresy to have curved stones then and it isn’t today. A hollowed stone may vary in depth but, by adjusting the angle of presentation longitudinally and laterally, you can create diversely varied curves to the cutting edges of tools according to task. Many craftsmen used a cambered iron in those days. It was more common than we think. That said, you can create cambered irons on flat stones too. To do that I might use a figure of eight method, but I can simply roll the iron too. Scrub planes are bench planes that employ the deepest curves. The problem with hollowed stones is the effect they have on the bevel of the tools such as chisels. If the stone is hollowed then the bevel is convex in both directions and the chisel edge of say a 1” chisel or a plane iron cannot be straight. In most chisel work we rely on the edges being as close to straight as possible. That means flat becomes generally a necessity. Flipping the chisels over and using the hollowed or even curved stone for the flat face is obviously devastating because even after just a few strokes it’s a lot of work to reflatten the face to remove the now curved corners.
Many people have restructured their thought processes. At shows about five years ago salespeople and gurus were set up with waterstones, flattening stones and baths of dirty water. No one would have set up with oilstones at that time because even though they worked fine and were clean and easy to use, they had become old fashioned and out dated. Today it’s changed all the more and the same people once selling waterstones are now set up selling diamond plates of different types because, I think, mostly people saw that flattening waterstones was messy looking, dirty wet, can be expensive and time consuming and oilstones are, well, old fashioned. Other stones like ceramic stones are options too and my choice outside of diamond plates might well be ceramic stones but they are not so easy to find. That said, my concern is getting people to the work at as low a cost as possible and especially for those who just don’t have the money for expensive stones and plates. The lowest cost start up is using stones. They cut steel effectively and they are not that expensive generally but you have to work at stopping them from dishing and especially is this so with narrow chisels and plane irons. It’s not so much the wider plane irons that cause the dishing and uneven wear issues although they do too, it’s the narrow blades that cut deeply and unevenly.
Personally I concluded long ago that flat diamond plates are the simplest and most effective long term solution to almost all of my sharpening edge tools. Long term they prove the cheapest too. I prefer non mechanical methods because in general it’s faster and more effective and very convenient. Every chisel and plane iron in the New Legacy woodworking school is still sharpened using diamond plates only and they (both tool and plates) do last and last well. I value what our forebears developed using stones alone and want to respect that their work was exemplary using dished stones and often stones unequal in quality to their ambitions. Stone makers have given us a vast array of water stones to work with and solutions to flatness and we can indeed keep one side curved and the other flat to reduce sharpening time or have separate stones for different tasks and tools. It’s still confusing to thumb through a tool catalog be that paper copy or online. Too much info’ creates a dearth of what it takes to understand it and that’s attention. Not many of us working people have the time to ‘pay‘ attention. I’m not sure if that’s going to change.