- Auto Paint Problems - Spray Painting Pitfalls - Eastwood Tech Library
Spray-Painting TroubleshootingWhether using an aerosol can, an HVLP system, or compressed air and a spray gun, the best way to apply automotive applications is to spray it. Sometimes, however, the final finish doesn't come out perfectly. Below are eight common problems, what causes them, and how to repair the finish.
Problem: Dry Spray: Dry paint dust settling over previously painted areas.
Causes: Paint drying too quickly; work piece too large to paint with an aerosol; application too slow; spray can is too far from surface.
Repair: Sand with a fine-grit sandpaper, followed by compounding and polishing; refinish as required.
Problem: Blistering: Bubbling, pitted or swollen appearance.
Causes: Trapped solvents; painting over dirt or moisture; rust under the surface.
Repair: Sand down and refinish; if necessary, sand down to bare metal. Ensure surface is completely clean before repainting.
Problem: Runs or Sags: Coating does not adhere uniformly to the surface being painted.
Causes: Paint drying too slowly; sprayed over wax, oil, or grease; finishing coats too heavy; paint can or work surface too hot or too cold.
Repair: If wet: use camel hair brush to brush out sag, then recoat surface. If dry: sand with fine-grit sandpaper, compound and polish; or refinish.
Problem: Orange Peel: Surface looks like the skin of an orange.
Causes: Paint can held too far away from the surface; shop temperature is too high (for best results, apply between 65°F and 75°F); spray nozzle is clogged.
Repair: Sand with 600-grit or finer sandpaper, and use a fine compound to rub out orange peel. If that fails, remove paint and refinish.
Problem: Spitting: Little or no paint coming from nozzle.
Causes: Nozzle obstructed or clogged; valve clogged.
Repair: Remove nozzle from can and put several drops of lacquer thinner in the valve. Do not poke or pick at the valve. Soak nozzle in lacquer thinner for a few seconds and replace the nozzle in can with a slight twisting motion. Do not push nozzle down into can.
Problem: Mottled Surface: Uneven appearance (generally affects metallic).
Causes: Paint can not shaken enough; paint can held too close to surface; surface too hot or too cold.
Repair: Re-spray as required using a swirling or rotating motion while spraying to deposit the metallic particles evenly on the surface.
Problem: Fish Eyes: Small crater-like blemishes in the finish.
Causes: Silicone on the surface; improperly cleaned workpiece.
Repair: If still wet: wash off paint. Thoroughly clean surface using Eastwood's PRE Painting Prep. Repaint surface.
Problem: Lifting or Wrinkling: A swelling or wet film.
Causes: Improper drying of the last coat; applying lacquer over enamels.
Repair: Material must be removed and the surface re-sprayed. Check content of topcoat and substrate coatings or primers before reapplying paint.