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Abrasives123

Choosing the proper abrasive for a particular job usually means the difference between one that is satisfactory and one that is super. Most home handyman chores will call for the use of what used to be called "sandpapers". However, the proper name for these now is coated abrasives. Here are a few basics to help your next effort to be super!

In selecting the proper coated abrasives, (4) four primary factors should be considered:

The abrasive mineral - the type of rough-stuff on the material.
The grade - the coarseness or fineness of the mineral.
The backing - either paper or cloth. paper comes in "a", "c", "d" or "e" weights. "a" (finishing) is the lightest weight for the lightest work. "c" and "d" (cabinet) are for heavier work. while "e" is for the toughest jobs.
The coating - the coverage of the mineral on the surface. Open-coated means the grains are spaced to cover only a portion of the surface. Closed-coat means the abrasive material covers the entire area. naturally, closed-coat abrasive will provide maximum cutting but will clog faster. It should be used for hard wood as well as hard metals. Open-coat is best on gummy or soft woods, soft metals or on paint.

Most Widely Used Coated Abrasives

Abrasive	Backing	Grades (readily available)	Broad uses
Flint	Paper (a, c & d weights)	Extra coarse through extra fine	Small hand sanding wood-removing paint. Clogs fast but very cheap. Great for gummy surfaces that would clog any paper used.
Garnet	Paper (a, c & d weights)	very coarse through very fine	Hand shaping and sending of wood. Also for cork and composition board. Cuts better and lasts longer than flint.
Aluminum oxide	Paper (a, c & d weights)	Very coarse through very fine	Hand or power sanding or shaping of wood. Also for metals, paintsmoothing or end-grain sanding.
	Cloth (x)	Very coarse through very fine	Mostly used for belt sanders.
Silicon carbide	Waterproof paper (a weight)	Very coarse through fine	To smooth coats on wood, metal, etc. for sanding floors, glass or plastics. Use wet with water or oil
Emory	Cloth (x & j weight)	Very coarse through fine	General light metal polishing. Removing rust and corrosion from metal. Can be used wet or dry.
Crocus	Cloth (j weight)	Very fine only	Super high-gloss finishing for metals.

There are (3) three popular ways to grade coated abrasives. The simplified markings (fine, very fine, etc.) used in the chart above give a general description of the grade.

- Grit actually means the number ofgrains which when set end-to-end would equal one inch.

- The "o" symbols are more or less arbitrary.

- The coarsest is 4.5, and the finest is 10/0 or 0000000000.

The table below compares these three methods of grading and gives general uses for different grades.

Comparative Grades and Uses

Grit	"0" symbols	Simplified markings	Uses
600 500	None None	Super fine	High satinized finishes-wet sanding
400 360 320	1070 None 9/0	Extra fine	High finish on lacquer, varnish or shellac top-coats - wet sanding
280 240 220	8/0 7/0 6/0	Very fine	Finishing undercoats or top paint coats-leaves no sanding marks - dry sanding
180 150	00000 0000	Fine	Final sanding of bare wood-smoothing
120 100 80	000 00 0	Medium
60 50 40	.5 1 1.5	Coarse
36 30 24	2 2.5 3	Very coarse
20 16 12	3.5 4 4.5	Extra coarse

Other finishing abrasives -

The best known of these include pumice, rottenstone, rouge and steel wool.

- Pumice is a volcanic abrasive, powderused for fine finishing. It is generally lubricated with water on oil and runs from 0000 down to 0.

- Rottenstone is a finer powder than pumice and is used to give an even higher sheen.

- Rouge is powder used mostly in the polishing of metal.

- Steel wool has a wider range of uses as shown on this quick reference table.

Grade	Uses
0000 Super fine	Primarily used by the home handyman in rubbing-down after the final lacquering, shellacking or varnishing.
000 Extra fine	Removes paintspots from woods - cleans polished metals such as stainless steel or chrome.
00 Fine	When used with linseed oil will satinize or dull a high luster finish on wood.
0 Medium fine	Okay for use in brass finishing - removes stains from kitchen and bathroom tiles and from better cookware.