A class coated abrasive products with 50 to 70% of the product surface covered with abrasive grains. Open coats are less likely to load when grinding soft materials though they are less efficient in material removal.
A coated abrasive product in which abrasive grain covers approximately 50-70% of the coat side surface to help resist loading.
related article A piece of sandpaper with abrasive particles that are spread out to prevent clogging. See also - closed coat.
Grit covering 70% or less of the surface backing of sandpaper is referred to as open-coat. This is used on softer wood or paint removal because the chips will not clog the sandpaper as easily.