Sandpapers In General:
Looking for just the right sandpaper (the usual nickname for sanding abrasives), can be somewhat of a challenge. You will find that you will settle in on a type and routine that you will feel comfortable with – it’s just getting to that point that can be somewhat time consuming.
Sandpapers are graded by four different factors:
Grit Type – Options include: garnet, aluminum oxide, silicone carbide etc.
Backing – Mylar cloth and paper among others.
Grit Size – The size and coarseness of the actual abrasive.
Bond – The adhesive that is actually used to attach the grit to the backing material.
Grading Scales Used for Abrasives:
CAMI: This is the North American Scale – Check the back of the paper. The CAMI scale will feature just the grit number of the paper. Also this paper has the least amount of uniform grit patterns. In other words it is much more likely to get a stray coarse grit in a finer paper in the CAMI graded paper.
These papers are the least expensive and work great for all kinds of wood sanding operations. As for sanding finishes, these paper are very useful for scuff sanding between coats to rapidly (and cheaply) taking down a finish.
JIS: This is the Japanese Scale – These are easy. They have Japanese characters on the backing. These may be quite hard to find, but they are very nice papers. They are most beneficial when used for fine, wet-sanding your finish. Cuts faster than CAMI graded paper for the same grit. Can be used in an orbital sander for fast sanding work. Typically higher priced than CAMI papers.
European P-Scale: These have the indicate of “P” before the number on the backing. Cuts faster than CAMI graded paper for the same grit. Well suited for fine, wet-sanding your finish. Can be used in an orbital sander for fast sanding work. Typically higher priced than CAMI papers.
Micron Scale: These papers have the micron indication of the Greek letter ‘mu’ or a modified “u” on the backside. Can be used in an orbital sander for fast sanding work. Typically higher priced than CAMI papers.
Micro Mesh: These are by far the finest papers available on the market today, with grits ranging up to 12,000. These work great for wet sanding where you don’t want to risk leaving behind and scratches that need to be buffed out, as in a very thin finish or a vintage finish where you can’t afford to sand to much without ‘going through’.
Typically, the higher the number of the abrasive grade, the finer the grit. For instance a 80 paper will be a coarse grit, while a 400 will be a relatively fine grit. Note that this pertains to all the paper grade with the exception of the micron paper grading. The higher the number for Micron Paper, the coarser the grit.
Recommended Grits For Guitar Use:
60, 80 and 120 Grit CAMI paper for rough-sanding and shaping bare wood.
120 to 220 Grit CAMI paper for general finish sanding of bare wood.
400 to 1200 Grit paper for finish wet-sanding a lacquer finish. Note: Finish up with 1200 just prior to buffing.