The Four Most Common Finish Defects, Their Causes, and Their Solutions

The finish of your product says a lot, after all it is the first thing a prospective customer sees. With so much riding on the coating appearance of your product it is important to minimize negative effects that can occur when finishing is not done right.  Below we will cover the most common finish defects and their typical causes.

1. Fish eyes – Fish eyes are the result of oil in your finish. The source of the oil could be the room air or from the atomization air if you’re using an air fed spray gun. To eliminate oil from your paint environment, you should utilize intake filters or isolate your booth from your shop with an air make up unit.  Additionally taking steps to minimize use of any silicone based lubricants near your finishing department or in rare cases in the plant will help eliminate fish eyes. This is because your spray booth will bring oils across the plant as it draws air for the booths operation. If you have a booth with proper filtration and have minimized any oil sources from your shop air, it is most likely coming from your atomization air. To properly eliminate oil from your atomization air you should utilize an air filter with at least an oil water separator.
2. Sandpaper finish – If your finish appears to be gritty or rough like sandpaper this is due to having excessive air pressure and not enough fluid being supplied to the gun during finishing, the solution is to decrease air pressure or increase fluid pressure. You may also need to reevaluate the air cap and fluid nozzle you are using.
3.   Excessive paint leading to runs – If your finish has runs in it most likely this is due to excessive paint coming from your spray gun. To reduce this you should either reduce your fluid pressure or use a smaller fluid nozzle allowing you to keep excessive coating use down to a minimum.
4. Air pockets in your finish – This is most often due to water in your atomization air. To eliminate this defect ensure you have an oil/water separator and if needed a desiccant dryer to remove all moisture from your atomization air.

These four problems are the most common finish defects we encounter. What other finish defects have you experienced and what caused them?