The first step was to prepare the surface of each part. Preparation for a waterborne basecoat requires sanding with a finer grit due to the paint's thinner dry film. This means that the actual solid layer that remains on the substrate after the reducer has evaporated is much thinner than that of a solvent basecoat. A thinner film will conform more to surface irregularities and grit marks. Solvent bases tend to hide more with a thicker film. Larger panels can be sanded with a random orbital dual-action sander but these pieces were simply scuffed by hand. Frank is working on the parts in the Training Center's prep station, which ventilates particles down and away. Without forced-air ventilation, you should always wear a NIOSH-approved respirator.