Which technique uses a sanding block to maintain a flat surface during sanding?

• A. Feather edging
• B. Guide coat
• C. Primer application
• D. Block sanding

Answer: (D)

Block sanding is the technique that uses a sanding block to maintain a flat surface during sanding. The block supports the sandpaper evenly, so pressure is distributed across a broad area rather than focused on your fingers or a small spot. This helps prevent creating dips, ridges, or waves and keeps the surface true and level. Maintaining a flat surface is crucial in collision repair because you want the panel to be uniformly smooth before applying primer and paint, ensuring even coverage and a seamless blend between panels. When you sand with a block, use long, steady strokes and check for flatness with your eye and hand feel, reloading the sandpaper as needed. Other techniques serve different purposes—feather edging shapes edges for blending, guide coat reveals high and low spots after sanding, and primer application involves applying the primer layer itself—so they’re not about preserving a flat sanding surface the way block sanding is.