SPI Guidelines – Mold Polish

Below specifications provide guidelines for mold surface finishes as provided by the Society of the Plastic Industry.  For more information visit Society of Plastic Industry.

SPI Finish


Typical Applications

A-1 Grade #3   Diamond Lens /   Mirror – requires 420 SS material
A-2 Grade #6   Diamond High   Polish parts
A-3 Grade #15   Diamond High   Polish parts
B-1 600 Grit   paper Medium   Polish parts
B-2 400 Grit   paper Medium   Polish
B-3 320 Grit   paper Med – Low   polish
C-1 600 Stone Low Polish   parts
C-2 400 Stone Low Polish   parts
C-3 320 Stone Low Polish   parts
D-1 Dry Blast   Glass Bead Satin   finish
D-2 Dry Blast   # 240 Oxide Dull   Finish
D-3 Dry Blast   # 24 Oxide Dull   finish