Quality prep work prior to applying body filler is crucial. It is the foundation of everything; so it better be right, and cutting corners is not acceptable.
Good rolocs are part of this equation. The metal needs a good enough ‘tooth’ in it for the filler to hold onto, but you do not want to grind the hell out of the metal, and put huge/deep grinder marks in it. You also don’t want to pour any extra heat into the panel.
These 3M Cubitron 2 rolocs are hard to beat. They are very sharp, and stay sharp for a long time. This allows you to use a finer grit; 60 grit, giving body filler the perfect surface for excellent adhesion without putting deep scratches in the metal.
3M has absolutely nothing to do with True Blox, this is just a good product that is important to properly prepping a panel for body work.
There are several important steps that come before this, which will be expanded on soon.