The Society of the Plastics Industry (SPI) sets standards for the plastics industry in the United States. One of the standards regulates the type of polish on molded plastic products.
There are twelve grades of finishes specified by the SPI in four categories that range from shiny to dull. Each grade has different requirements for allowable deviation from perfect, with lower numbers allowing for less deviation and higher numbers allowing for more deviation. The list below shows all of the finishes specified by SPI.
| ·A-1 (Grade #3 Diamond Buff)
·A-2 (Grade #6 Diamond Buff) ·A-3 (Grade #15 Diamond Buff) ·B-1 (600 Grit Paper) ·B-2 (400 Grit Paper) ·B-3 (320 Grit Paper) ·C-1 (600 Stone) ·C-2 (400 Stone) ·C-3 (320 Stone) ·D-1 (Dry Blast Glass Bead #11) ·D-2 (Dry Blast #240 Oxide) ·D-3 (Dry Blast #24 Oxide) |
