Painting Radiators a Complete Guide
Radiators can be difficult to spray paint on as they have a variety of unique considerations from fins that block the internals of the radiator to concerns about paint bridging across the radiator fins blocking proper air flow across the radiator. I spent my day this previous week helping a radiator repair shop achieve success in effectively painting their radiators. In particular, they wanted to be able to spray paint inside the radiator so that the radiator would be completed painter both externally and internally, the goal of this being to reduce corrosion problems and improve the longevity and quality of their radiators.
How we sprayed the inside of their radiators (Equipment Choices)
The current solution that was being used were gravity fed HVLP spray guns which would work after thinning the paint and would only paint the exterior of the radiators with a relatively thin enamel. However to improve protection for the radiators and paint internally a two part epoxy paint was selected for its improved durability. This paint wouldn’t spray well without excessive thinning due to being thicker (more viscous).
In order to be able to force paint through the radiator well and move the paint to the spray gun efficiently we chose a 2 gallon pressure pot with a conventional spray gun. The benefit of using a pressure fed spray gun system is that it allows control of your fluid pressure to be separate from your atomization air. The benefit of the conventional spray gun over HVLP Spray Guns is that it allows for better atomization of thicker paints and pressure can be turned up high to force material through the radiator fins. While gravity and suction are limited in the force that material is fed to the spray gun.
The Way We Set The Equipment
Typically you keep air pressure as low as you can while still achieving the desired break up of your paint. However, we wanted to force material past the radiator fins and into the radiator itself to provide coating protection of the interior of the radiator. To accomplish this we used a lot of air pressure (about 50 PSI in our dual regulated pressure pot). We also left fluid pressure lower (around 10 psi) so that the paint would be sprayed at a high speed and be able to get past the fins. We used a Binks 2100 Spray Gun with a large air cap so that the paint would be effectively broken up. The end result was that we could spray the paint in a fine break up past the radiator fins and achieve a smooth finish that coated the outside and insider of the product.
Other potential options for painting radiators
While we used a conventional spray gun it may be possible to use other options like an airless paint sprayer but the waste would likely be higher. If your fins are not really close together you may also be able to achieve the same result with an HVLP spray gun while reducing waste. However, we found the conventional spray gun and 2 gallon dual regulated pressure pot worked well. If you have questions or need equipment to paint your radiators inside and out we can help.