A Roloc Grit Question

[mobiledynamics]

The Roloc Bristle Disc - the green one (50 grit). Compared to the yellow or white.
Is the Green not abrasive to the point if I want to use it not he aluminum portions of a rotor hat ?

 

[dnschmidt]

Green is the coarse (50 grit) normally used with cast iron, yellow the medium (80 grit) and white the fine (120 grit) Use white with aluminum as the other too can dig into aluminum and ruin a machined gasket surface.

 

[mobiledynamics]

thx. I guess I'll need to add white to the stash. Grit rating aside, I was sure if *50* was really *50* since it seems to remove or not remove as much material as your standard grit disc type.