I have a set of sandpapers that has the following papers:

 60 AN
100 GB
120 DN
180 FB

All have the marking S/C/W/P paper T9 C Closed. These are all paper sheets. I know that the number is the grain size.

What do the other markings mean?

Especially the 100 GB. I've noticed that it behaves somewhat different to its grit size compared to the others. I am guessing that the G means its the thickest paper? The backside looks different compared to others.

  • 1
    The Googles! They do nothing! -- My best guess is that they're manufacturer specific codes regarding backing and abrasive type. I could find no standards other than three different grit standards. Dec 4, 2014 at 21:33
  • what industry is the paper made for (metal, wood, other)?
    – user23534
    Dec 5, 2014 at 2:49
  • @paperstreet It says that its an assortment of waterproof and "Sanding Sheets for Aluminum, Soft Metals, and Nonmetals". I also found out that letters A to F are rigidness of the packing. This seems to make sense as paper marked with "AN" is the most flexible one.
    – Juha
    Dec 8, 2014 at 19:11

1 Answer 1


According to this site:

The weight of the backing is usually designated by a letter. For paper backings, the weight ratings range from "A" to "F," with A designating the lightest and F the heaviest. Letter nomenclature follows a different system for cloth backings, with the weight of the backing rated J, X, Y , T, and M, from lightest to heaviest.

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