|US oil stones(grit)||100||180||240||600||700||900|
|Japan water stones(grit)||250||1000||1200||4000||6000||8000|
|Ceramic (Microns)||7 - 8||4 - 5|
The above chart is only a guideline and not hard and fast rules. A course water stone may be anywhere from 400 to 1200 depending on what a particular manufactures offers. Just remember with grit and mesh the lower the number the courser the stone and the higher the number the finer(smoother) the stone. With microns just the opposite is true. The high the number the courser and the lower the number the finer the stone is. Which is all well and good until you see Arkansas stones listed as soft, hard, hard black, true hard and translucent. That roughly translates into Soft = 500 grit, Hard = 700 grit, Hard black = 900 grit and I would have to guess that True hard and Translucent are about equal and something higher than 900.
Most sharpening stones use a lubricant (oil or water) to keep the removed metal particles from clogging the cutting surface of the stone. Without the lubricant the metal would form a glaze on the surface of the stone and would greatly diminish the metal removing ability of the stone. Oil used for sharpening should be a light weight machine oil. like sewing machine oil, 3-in-1 oil or a special honing oil. You want an oil that is thin and not gummy. Ceramic and some diamond stones can be used dry. A whet stone, not wet stone can be either an oil, water or dry stone.
Oil stones are probably the most common in the US. They can be found in old tool boxes or kitchen junk draws. These can sometimes be found at flea markets and garage sales. Sharpening a knife on an oil stone creates a wire edge or burr on the edge of the blade. The finer the stone the finer(smaller) the wire edge. To have a truly sharp knife this edge must be removed, usually by stropping.
WASHITA A coarse natural stone used to form a new bevel or edge and to reshape a tool. Cost $10 to $15.
INDIA STONE A man-made aluminum oxide stone usually found as a combination of coarse(100 grit) on one side and fine(280 grit) on the other side. A good general purpose sharpening stone. Start on the fine side with fairly dull tools. Cost $15 to $25.
ARKANSAS Natural stones that can be used with water but most people use oil. Probably the most commonly used stones for fine tool sharpening.
Soft A good stone for general sharpening of knives and other tools. A good starting stone for slightly dull knives. Cost $1.50 to $15.
Hard A good stone for putting a fine edge on a knife or other tool prior to stropping. Cost $5 to $25.
Hard Black A very good finishing stone (my favorite) prior to stropping. Cost $10 to $35.
True hard and Translucent Rare specialty stones used for surgical and dental tools. Cost $69 to $125.
SILICONE CARBIDE A man-made usually coarse to medium stone use to repair damaged edges and reshaping . Very common at hardware and discount stores . Cost $2 to $12.
TRI-STONE/TRI-HONE. Three different grits of stones
are mounted on a triangular piece of wood or plastic supported
on each end and rotated to use the stones. Combinations vary
from coarse silicone carbide, medium soft Arkansas, fine aluminum
oxide to soft Washita, medium hard Arkansas, extra-fine hard
black Arkansas. Also oil-bath units which the stones are rotated
in to an oil tank as part of the unit. Cost $12 to $40 oil bath
$25 to $170.
Water stones are the main sharpening stones in Japan. Water is used to float the metal particles above the stone. Water stones are more porous and softer than oil stones thus they expose more fresh particles and are faster cutting. But wear out faster than oil or ceramic stones. When using a finishing stone a wire edge is not formed. Therefore it does not have to be removed by stropping ,saving a step. Most water stones must be soaked prior to being used. Some carvers store their water stones in a Rubbermaid or Tupperware box filled with water. There is two general groups Course (200 to 1200 grit) and Finishing (2000 to 8000 grit).
AOTO (Mountain Blue Stone) 2500 to 3000 grit cost $55
AWASE TOISHI Finishing stones various grades cost $80 to $175.
Coarse Stones, range from 80 grit to 1200 grit and are made from various materials (Green Carbide, Silicone Carbide, Chromium Oxide, Aluminum Oxide). Cost $14 to $40 .
Finishing Stones, range from 4000 to 8000 grit and are made from various materials. They may contain special binders that absorb water and act as polishing compounds. The mud produced while sharpening polishes the blade. Cost $20 to $80.
Nagua stone. A natural chalk stone used to rub on finish stones to create a paste that lubricates and polishes. Also a man made version is available. Cost $8 to $13.
Combination Water stones are available in various combinations 100/180 grit, 220/800 grit, 800/4000 grit, 1000/6000 grit and 1200/8000 grit. Cost $20 to $45.
Are made from a super hard bonded Aluminum oxide or Poly-crystal ceramic powder both of which are just below diamond on the hardness scale. They do not require any lubrication so they can be used dry or with oil or water. Using them dry makes them less messy than water or oil stones. However some people dislike the sound made when they are used dry. They seem to be preferred by chip carvers as both Wayne Barton and Dennis and Todd Moor have developed sets of them.
Medium dark or black approximately 700 grit. Aggressive cutting for fast material removal. Used for reshaping and initial sharpening. Cost $20 to $25.
Ultra-fine white about equal to the Japan 6000 grit. Used for final honing prior to stropping. Some Woodcarver list members claim they don't need to strop after this stone. Cost $20 to $25.
Diamond stones come in at least two varieties. Monocystalline
held in plastic and Polycrystalline bonded to steel or aluminum
plates. Monocystalline requires water for a lubricant.
Polycrystalline can be used dry.
The stones normally come in the following grits: Course 220 , Medium 325, Fine 600, Extra-Fine 1200. Cost $25 to $75.
The basic stones used for sharpening gouges are the Slip stone and the Cone. The slip is shaped like a rectangle with one long side rounded and the other long side tapered down to a thin edge. The cone is shaped like a ice cream cone cut in half lengthwise with both a concave and convex sharpening surface. There are ceramic files and carbide sticks in various shapes(round, diamond, square, triangle, heart) plus tapered rounds, triangles and points. They are available in most of the listed materials from carbide to diamond and Arkansas to water stones. Costs vary from $10 for set of six to $80 for set of three.
Arkansas stones left to right Hard Black pocket stone, Hard Black slip, Hard slip, Soft slip.
After the stones comes strops which I hope to cover in a future
article. There is also a whole world of power sharpening with
as many or more gizmos and gadgets then stones I have listed.
They do a great job of sharpening and do it very quickly but
take considerable skill, space and money.
What do you need to start out? Well if you obtained ready to carve sharpened tools you can get by with a hard Arkansas stone and strop. A decent 6" Tri-Hone is a very versatile unit and could handle most of your sharpening needs. I personally like to go from soft to hard to hard black Arkansas and then to a strop. It is nice to be able to go to a progression of increasingly finer stones but it is not absolutely necessary. But the greater the span between stones the more strokes that are required on the finer stone. It's the classic trade off of time(many strokes) or money(many grades of stones). Besides bench stones(larger than 4" X 2") you may want a pocket stone(4" X 2" or smaller) or two to take with you and your pocket knife.
The following companies offer catalogs that list various sharpening stones and tools. They also serve as a good reference source. A lot of the information contained here came from these catalogs. Woodcraft is a must have for any woodworker. The Japan Woodworker has a lot of fascinating tools different then found in most other catalogs. Smoky Mountain Knife works has great prices on pocket knives and sharpening stones. MHC are very nice people to deal with and can meet most of your carving needs.