Sandpaper

By fix it club

Most do-it-yourselfers still refer to various grades of “sandpaper,” but the proper term for these sanding sheets is “coated abrasives.” There are four factors to consider when selecting any coated abrasive: the abrasive mineral, or which type of rough material; the grade, or the coarseness or fineness of the mineral; the backing (paper or cloth); and the coating, or the nature and extent of the mineral on the surface.
Sandpaper
Sandpaper can be held in the hand or wrapped around a sanding block.
Paper backing for coated abrasives comes in four weights: A, C, D, and E. A (also referred to as “Finishing”) is the lightest weight and is designed for light sanding work. C and D (also called “Cabinet”) are for heavier work, while E is for the toughest jobs. The coating can be either open or closed. Open coated means the grains are spaced to only cover a portion of the surface. An open-coated abrasive is best used on gummy or soft woods, soft metals, or on painted surfaces. Closed coated means the abrasive covers the entire area. They provide maximum cutting, but they also clog faster and are best used on hardwoods and metals.

There are three popular ways to grade coated abrasives. Simplified markings (coarse, medium, fine, very fine, etc.) provide a general description of the grade. The grit refers to the number of mineral grains that, when set end to end, equal 1 inch. The commonly used O symbols are more or less arbitrary. The coarsest grading under this system is 4 1/2, and the finest is 10/0, or 0000000000.

The following chart contains information on sandpaper types and uses.

GritNumberGradeCoatingCommon Uses
Very coarse30
36
2 1/2
2
F,G,S
F,G,S
Rust removal on rough-finished metal.
Coarse40
50
60
11/2
1
1/2
F,G,S
F,G,S
F,G,A,S
Rough sanding of wood; paint removal.
Medium80
100
120
0(1/0)
00(2/0)
3/0
F,G,A,S
F,G,A,S
F,G,A,S
General wood sanding; plaster smoothing; preliminary smoothing of previously painted surface.
Fine150
180
4/0
5/0
F,G,A,S
F,G,A,S
Final sanding of bare wood or previously painting surface.
Very fine220
240
280
6/0
7/0
8/0
F,G,A,S
FAS
FAS
Light sanding between finish coats; dry sanding.
Extra fine320
360
600
9/0

_2
_2
FAS

S
S
High finish on lacquer, varnish, or shellac; wet sanding.
High-satinized finishes; wet sanding.
SELECTING SANDPAPER

1 F = flint; G = garnet; A = aluminium oxide; S = silicon carbide. Silicon carbide is used dry or wet, with water or oil.
2 No grade designation.


My Thoughts

There are higher grits of course that I have seen up to 7000. They possibly go even higher however, the likelihood that you will ruin your timber is high. From experience, the coloured high grit sandpaper above 2000 will burn its colour onto the wood when using a lathe. Even if you sand with a very light touch, it still occurs. The same cannot be said for grey coloured sandpaper. The 3M 3000 grit foam is an excellent choice for sanding the final coat.

3000 Grit

It’s fine to use on a high-speed lathe, but don’t expect to leave enough grit for second rounds. Hand sanding is fine. I have successfully reused this paper at least 15 times before I had to discard it.

The other one is their next grit size up the 5000 grit.


The colour of this is blue and without a doubt will leave its colour embedded on the wood if used on a lathe. The same will apply even if applied by hand. If you concentrate too much on a particular area, the heat will build up quickly and melt the paper onto the wood. This is extreme, but I have done it. Using this paper will aid in burnishing. The cost of 3M paper is ridiculously expensive, and I do not understand how they can justify it. I don’t know of any other company who makes foam pads of this type.

If you wish to burnish your project you must be made aware that irrespective of how small and insignificant the mark on your work is, it will be highlighted significantly when burnished. Just like all marks are highlighted by the stain when staining, so will any damage be highlighted on burnished timber.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s