My second time spraying urethane prime, and I’m struggling to get it to lay flat. It sprays like its too dry but does flatten (not completely) after it drys a bit. I’m using an Eastman 2k urethane primer in a 4 to 1 mix sprayed from an Eastman Contours 2 spray gun with a 1.7 tip. The tech sheet recommends a 1.5-1.7 tip and sprayed at 25-30 psi at the gun. I have a pressure regulator attached to the gun and tried 25 to 30 psi. The temperature in the garage at the time I sprayed was about 55°.
It’s not a big deal as I’m block sanding it anyway, but you’re supposed to be able to use it as a sealer then top coat it without sanding, so I’m sure my technique needs to be improved.
The pictures are immediately after spraying, then after it settled a bit, in addition the tech sheet.
Any suggestions would really be appreciated.
Last edited by Phak1; 12/06/20242:19 AM. Reason: Typo
Phil Moderator, The Engine Shop, Interiors and Project Journals
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Maybe lay it down a little heavier (slower gun travel?) Also your data sheet suggests using up to 20% reducer. That will help it flatten.
I haven't sprayed urethane primer, but adding some reducer sure helped with my top coat, which says it can be sprayed right out of the can.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
55 degrees is pretty cold for spraying auto finishes but that would normally result in sags, runs, very long flash time. What was the temperature of the metal? did you have a lot of air movement? It appears that you have too high air volume/too little liquid, or the gun is too far from the panel or moving too fast across the panel. I would cut the mix with the fast reducer due to low ambient temperature and practice on some disposable surface. The PPG epoxy primer that I have used lays very smooth and needs zero sanding, I use a conventional siphon gun at lower pressure than recommended or an airbrush.
1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy
I had a similar experience and was advsed to lower my pressure which may align with 78buckshot's comment about too much air volume. It seemed counter intuative to me but I do not hav much experience.
If I were painting that, I would turn up the air pressure to get the material to atomize more. If it was still giving me issues, I would reduce the product a little, if I could.
