Unique Research Explains Subtle, But Costly, Automotive Finishing Challenge

An original equipment manufacturer (OEM) noticed something wasn’t quite right in their automotive paint shop after holiday breaks. Certain colours or metallics that previously provided Class A, new car finishes went flat or lacked lustre when the factory resumed production.

The now defective paint had to be cleared out of their circulation system. In addition to hundreds of litres of waste, many parts had to be redone or discarded.

Why was this happening? The automotive OEM asked liquid finishing experts in Graco’s Industrial Division to figure it out. What they learned equipped them to go back to the OEM to teach them about paint degradation and how to solve their post-holiday problem.

Graco published their findings in a five-page white paper titled Paint Degradation in Paint Circulation Systems. Blake Erickson, the white paper’s author and Graco’s global product manager for circulation and supply pumps, recently answered our questions about the unique research.

Paint degradation is the change in light reflection on a finished surface due to changes in the coating’s ability to reflect light. It usually happens when you have metallic particles your paint. As they repeatedly move through a circulation system, the particles crash together and deform. As a result, the light reflecting properties of the paint change – usually not in a good way.

To achieve that really classy new car finish, automotive OEMs and their subsidiaries use metallics and special colours. Those coatings are prone to shearing issues that can lead to paint degradation.

When we’re trying to figure out if an automotive factory has paint degradation concerns, we’ll ask whether they’re happy with things like colour match or paint quality. We’ll also ask about wasted material and rework of vehicles. In plants where they have this issue, you might see a line of cars or parts that have to be sanded down and sent back through the finishing line.

It depends on a lot of factors, but a big one is paint waste. Let’s say your paint circulation system has a 1136 litre (250) gallon tote and there's another 455 litres (100 gallons) in the line itself. That's 1591 litres (350) gallons. The price of your metallic paint or special colour is about $100 to $125 per 4.55 litres (one gallon). Having to dispose of that particular colour can cost you $35,000 to $43,750. Multiply that out over a couple of colours in that plant and you're finding a huge expense.

We did a lot of testing and realised we needed to get very scientific about it, so we came up with a process to figure out where the problem was coming from. Along the way, we learned a lot about paint degradation.

Paint shear happens. Proper circulation system design and active management techniques can keep it from leading to paint degradation and waste. To learn more, download the white paper from graco.com/paint-degradation.

Anyone who needs to know how to keep making good, Class A finishes, while avoiding the high disposal costs of paint that no longer produces the appearance desired.

We’ve upgraded seals and checks in our circulation pumps, designed a low shear back pressure regulator (BPR) with a unique flow path geometry, and developed a non-production or sleep mode in our Intelligent Paint Kitchen System.