mottling, explained in detail?

John Long

I have been following this thread with interest. Remember, I am a street rodder and paint a car every couple of years, but I have a couple of thoughts that might interest the hobbyists who read this.

In the old days, painting Acrylic enamels, a light tack coat was a great idea and would really help you spray wet which was necesary in those days. Without a tack coat it would really turn loose on you. A final coat at 8-10 inches would evenly distribute the metallic and greatly reduce mottling.

The modern urethanes are a completely different animal. A lot of guys really hang on to the old methods and the things they are told by those who were doing the work 20 years ago. The first coat of the urethane needs to go on wet just like the second or third but wet does not mean loading it on. Wet means shooting it so the paint becomes a smooth and shiny surface. The other thing that is different is the metallics don't need to be flooded on. They need a wet surface only, and to be honest, it is better that the last coat be a little dry than too wet. The temptation to really lay it on the hood, trunk, or roof, has messed many new painters up. Careful, even application with gun parallel to the surface, with the 50-75% overlap will get you there. Don't worry that your base flashes dull. It is designed to be that way. The clear furnishes your shine.

There has never been a time when metallics were more user friendly but, that does not mean they do not require additional care and skill than the solid colors. I personally prefer painting the solid colors but am amazed at how far the technology has developed. With a gun that is performing properly, a quality job is very do-able for a lesser experienced painter.

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This is the Standox TDS. They recommend using the intercoat (colorless base) and reducing pressure and using the droplet technique if needed. So, it's apparently not an unnecessary process.


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NextGen Classics

Floor sweeper
What I do to make sure I avoid metallic issues: use a quality (clean) paint gun, base and clear on a test panel to assure gun setup,number of coats for coverage and correct air pressure. Take panel outside in sun and look at it closely.Your air supply set up is critical.also good lighting.

You want to be physically fit to paint a car properly,if you're arm gets tired you got problems. I also do a dry run over the car just prior to cleaning and tacking,this helps me decide the best route to take over difficult areas while maintaining proper distance,hose routing and step stools if needed.

As with all the other good advise above,have a good,well thought out plan and it will go just fine.