Paint Correction: Removing Runs

Applying the perfect final finishing to any classic car is rarely a perfect process and there are a number of things that can or will go wrong during the process, but what separates a good paint job from a great paint finish is knowing how to correct any flaws that do occur. Common issues in garage painted cars include dust nibs in the finish, runs and sags or a rough finish often referred to as orange peel. Mark Simpson joins up with expert body man Matt Roehrick of MCA Customs to demonstrate how to remove runs and sags in an automotive finish.

Roehrick explains, correcting and removing paint runs in classic car finishes requires patience, the right tools, and proper technique to maintain a smooth, show-quality finish without thinning out the paint too far.

Here’s a step-by-step guide to fixing paint runs effectively.

Tools & Materials Needed

– Fine-grit wet/dry sandpaper (1000, 1500, and 2000 grit)
– Rubber sanding block (for even pressure)
– Razor blade with masking tape (optional for severe runs)
– Spray bottle with water and a few drops of dish soap
– Microfiber towels
– Dual-action (DA) polisher or rotary buffer
– Rubbing compound (such as Meguiar’s or 3M)
– Polishing compound

Step-by-Step Process

Step 1: Initial Inspection & Preparation
– Identify the paint runs and ensure the paint is fully cured (at least 24-48 hours, longer for some classic car paints).
– Wash and dry the affected area to remove any dirt or debris.

Step 2: Leveling the Run (Optional Razor Blade Technique for Heavy Runs)
– If the run is very thick, wrap masking tape around both edges of a razor blade, leaving only the center exposed.
– Hold the blade at a shallow angle and carefully scrape the high spots off the run in smooth, controlled strokes.
– Stop when the run is nearly flush with the surrounding surface.

Step 3: Wet Sanding
– Fill a spray bottle with water and a few drops of dish soap.
– Start with 1000 or 1500 grit wet/dry sandpaper wrapped around a hard rubber sanding block.
Keep the surface wet and sand in a circular or straight motion, using light pressure.
– Regularly wipe and inspect the area to prevent sanding too deep.

Progression of Grits:
– Once the run is mostly level, move to 2000 grit for a smoother finish.
– Sand until the area blends seamlessly with the surrounding paint.

Step 4: Polishing the Surface
– Use a rubbing compound with a dual-action polisher (or by hand with a foam applicator) to restore gloss.
– Apply a polishing compound next to further refine the finish.
– Buff until the shine is restored and the sanded area matches the rest of the paint.

Tips
– Always use a sanding block to maintain an even surface.
– Keep the surface wet while sanding to reduce heat and scratches.
– Avoid excessive pressure to prevent cutting through the clear coat or paint.
– If working on single-stage paint, be cautious as there’s no separate clear coat to protect the color.

Matt concludes: By carefully following these steps, paint runs can be effectively removed, restoring the paint’s smoothness and showroom-like finish on your classic car.