Who is correct regarding the application of body filler?

Technician A's assertion that rough filler takes extra time to sand off is correct because when body filler is applied too thickly or is unevenly mixed, it creates a rough surface. This roughness makes the sanding process more labor-intensive and time-consuming since the technician must spend additional effort smoothing it out to achieve the desired finish. An optimal application of body filler should aim for a smooth, even layer to minimize the amount of sanding required.

In contrast, Technician B's statement that filler should be applied thickly is misleading. Ideally, body filler should be applied in thin layers, as this allows for better adhesion and easier finishing. Thick applications can lead to issues such as poor curing, cracking, or the filler not adhering properly to the substrate, which would necessitate more work down the line.

Thus, focusing on the guideline of applying body filler in thin layers, it becomes clear why Technician A's perspective is the one that aligns with best practices in body repair.