Category: Abrasives

Some basic info

I don’t profess to be an expert on this stuff so I am only passing along what I’ve learned over the years.

For woodworking and metalworking you generally use different types of abrasives that are specific to the job. There are many to chose from Aluminum Oxide to Silicon Carbide to Diamond. What you use depends on the project materials.

Sanding, scraping, polishing, grinding all have the same desired effect–to remove material to get the desire shape. Sanding involves scratching the material with paper to which grit has been affixed (think very tiny rocks). You use finer and finer grits to remote the scratches from the prior grit until you get the smoothness you like.

From left to right, course to finer. 80 grit, 100 grit (see the large size of the particles), 220 Grid (fine), 600 Grit and 2000 Grit. At this fine a grit you cannot see the individual particle and the sandpaper feels almost like a sheet of looseleaf paper. Once you get finer than the 500 Grit you generally work ‘wet’, using a lubricant such as soap & water or mineral spirits (my favorite). This helps wash away the fine dust of the material and keeps the fine paper from clogging with it, which would make the paper smooth and render it useless.

Ultra fine grit sandpaper (actually mylar at this point) can be used on steel to get super sharp edges and very flat surfaces. These are 5000 and 10000 grit and feel almost like plastic at this grit.

5000 and 10,000 grit mylar ‘paper’

Stones that are uses for sharpening metal tooling such as drills, end mills, knives and plane blades. I use these for all of that. The flat stones are oil stones to which you add oil while grinding on them to lubricate and remove the particles during the process. When they get bumpy or non-flat from use, you grind one on another harder stone to ‘true’ it back to flat.

Abrasive Stones. Oil stones on the left, water and soapstones on the right for finer, software sharpening.

Diamond stones. Not actually a stone, but a metal surface to which tiny diamonds have been affixed. These are used for sharpening certain types of cutting tools such as carbide.

Diamond stones. See the pretty glitter? The green ‘dots’ are lot spaces that allow the lubrication to carry particles away from the diamonds and keep them sharp.

When sharpening, there is a point where you are removing so little metal to get a fine edge that you are Honing and approaching polishing. At this point you move from the fine stones and sandpaper to something like a strop. Some people use a powered wheel but I prefer the strop for finer control. I have three stops I made by gluing 24″ of leather to flattened wood. The first strop is “charged” with an abrasive compound.

Several of my abrasive compound sticks, from Red Rough to white. I believe the white is considered approximately 30,000 grit.

These compounds are something like a soft wax that has been mixed with ultra fine abrasives. This is not unlike toothpaste, which is an abrasive in a liquid carrier for polishing teeth. You rub the compound stick (they feel like big crayons) on the leather, then hone the object on the leather strop several times. By moving from more abrasive compounds to finer, and then finally just the plain leather strop you hone the last of the roughness away.

Lightly charged course strop, green medium charge strop, and plain leather fine strop.

The process is usually the same for wood or metal. For smoothing, start with a course grid (whatever the medium) then remove material gradually, then go to the next approximate doubling of grit. I.e. 80, 150, 220, 400, 800, 1500, etc. If sharpening metal, I usually then hone with 2000, 4000, 10,000. Then polish with compounds to the finest grit you have until you get a mirror finish.

Abrasives