How do you read a sandpaper grit chart?


Quick Answer

A sandpaper grit chart lists the particle size of each sandpaper grade recognized by major federations and standards boards in the abrasives industry. A chart also includes the texture gradation that describes each size range. Grit size charts are typically divided into macrogrits and microgrits; the former includes grits with an average particle diameter between 68 and 1815 microns, whereas the latter includes grits with an average particle diameter between 8.4 and 58.4 microns.

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Full Answer

In the United States, sandpaper standards are set by the Coated Abrasives Manufacturer's Institute. Worldwide, the most common production standards are set by Federation of European Producers of Abrasives in its “P” series of gradations.

Grit charts list average particle diameters in microns and divides them into texture categories from Extra Coarse to Ultra Fine. Each FEPA and CAMI grade is listed adjacent to its particle size. The smaller the particles, the larger the grade. FEPA grades begin with P and range from P12 (1815 microns) to P2500 (8.4 microns). CAMI grades are numerical and range from 24 (708 microns) to 1000 (10.3 microns). Not every FEPA grade has a corresponding CAMI grade.

To determine the ideal sandpaper grade by coarseness, look for the FEPA/CAMI grade corresponding to the desired texture and particle size. To determine the grit size of sandpaper, look for the particle size corresponding to its FEPA/CAMI grade. Larger particles create coarser sandpaper.

CAMI grades are defined by average particle diameter, while FEPA grades are defined by the percentage of particles that fall within a given range of particle diameters. The average of this range is used to list FEPA grades grit size charts.

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