Bill Boyton is a member of the Garden Club of Austin and the Austin Bonsai Society and has been sharpening tools for many years. He presented to our club for the May, 2014 meeting and provided the following information on sharpening your garden tools:
​
This is from Woodcraft Catalogue and other sources and compares the approximate abrasive grit relationships of American and Japanese stones:

Stone Type	US Grit	Japanese Grit
Coarse Crystolon, Coarse India	100	150
Medium Crystolon	180	240
Medium India, Coarse Diamond	240	280
Fine Crystolon, Fine India	280	360
Medium Diamond	320	500
Washita	350	600
Soft Arkansas	500	1000
Hard White Arkansas, Fine Diamond, Medium Black Ceramic	700	1000
Hard Black Arkansas	900	4000
Ultra-fine White Ceramic, extra-fine diamond	1000-1200	6000

​Following is a list of several abrasive papers that will have finer US grit ratings. A US 1500 is approximately equivalent to a Japan 8000. Some polishing and honing abrasives are listed by particle size in Microns. One Micron is 1/1000th of a millimeter. There are approximately 25,400 microns in an inch. Note: Particles smaller than 10 microns can be a respiratory hazard.

• Aluminum oxide = (color varies- grey, white, reddish-brown or dark) cloth backed emery
• Ceramic is Aluminum Oxide heated to 3000 degrees F under pressure
• Silicon-carbide = (blue-black color and harder, sharper and more brittle than aluminum oxide) Crystolon, wet-dry cloth and paper

Useful Web Sites:

• Woodsmith
• Woodcraft
• Grainger

You can also download the helpful Sharpening Guide Article from Woodsmith.