Drop coating metallic auto body paint

Drop coating is an important skill that all body paint sprays should aim to master. The drop coat is administered at the final stage of the spray process where metallic paint is used. When applied correctly to the body panel, the drop coat provides a full color cover, a perfect metallic content distribution, and a better paint base that can easily accept the lacquer.

Apply metallic paint

Drop coating should be used with all metallic autopaints. Many paint sprays apply a metallic base coat using the same method as applying a single color. This is a common error that otherwise impairs perfect work. Horizontal arm movement is ideal for most monochromatic spraying tasks, but metal body paint should be dropped onto the panel as soon as basic coverage is achieved. It is just as important to crosscoat the final application horizontally and vertically.

Ensuring a uniform coating range

Before applying the drop coat, the prepared car panel should be properly covered with a metal body paint to avoid the transparency of the primer. Once the color is active, the surface of the panel should be completely sprayed with wet coat paint. To ensure uniform coverage and distribution, it is essential that each horizontal spray operation blends in with the previous operation (30% to 40% overlap is optimal). Immediately after applying the single coat, the car body paint should be allowed to dry for about 10 minutes. Do not spray the second coat until the first coat has a matte appearance.

Apply a second coat of metallic paint

Personally, I like to spray the next paint in a different direction than the first paint, especially when the panel is removed from the car. This may not be possible if vertical panels such as fenders and doors are still attached to the vehicle. If you’re happy with using a regular horizontal spray pattern, don’t worry. The second application should be sprayed in the same way as the first application, but try to achieve 80% wetness compared to the previous application. Once again, the car body paint should be allowed to dry for about 10 minutes until it becomes matte.

Apply a drop coat

If the metallic paint is still transparent, you may need an additional coat, but in most cases this is not needed. To spray the actual drop coat, place the spray gun 18 to 24 inches away from the surface of the panel and reduce the pressure on the gun by 20% to 30%. Spray the car body paint horizontally and slowly move the arm across the panel to allow the metallic color to fall (or fall) onto the surface. Maintain uniform coverage until the spraying process is complete. Immediately recoat the panel from the same distance, but swap the horizontal movements vertically so that the next coat intersects the first coat. Crossing the drop coats not only guarantees a uniform coverage, but also provides a uniform metal distribution and an excellent surface that properly accepts the lacquer.

Drop coat tack

Allow the drop coat to dry before visually inspecting the metal body paint. Check for patches that may have inconsistent coverage and spray more dropcoats as needed. For solvent-based body painting, it is recommended to tack the vehicle panel as soon as the drop coat dries. You can buy a specialized tack cloth for water-based body painting, but it is advisable to abandon the tack process as a large buildup of paint can cause discoloration and lead to frustrating retouching.