Spray Painting Troubleshooting

Posted: May 6, 2020 By: MattM

Whether using an aerosol can, an HVLP turbine 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: Start by spraying Injected Aerosol Cleaner through the gun to break any debris free. This can be done with the gun assembled. For full rebuild and cleaning of the gun use dedicated Paint Gun Cleaner by soaking the gun and parts in a clean mixing cup.

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 work piece.
Repair: If still wet: wash off paint. Thoroughly clean surface using Eastwood’s PRE Painting Prep. Repaint surface. Mixing in Fisheye Eliminator into your urethane coatings to help flow out the coating and reduce fish eyes. Install an Inline Fisheye Filter to reduce contaminates from entering the paint gun.

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 compatibility of topcoat and substrate coatings and primers before reapplying paint.

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