Ask the Expert Question-and-Answer Archive

by Ron Joseph

May, 2009

Orange Peel

Q. I am restoring and old farm tractor and am having difficulty with orange peel. My first attempt was probably caused by low pressure on the gun. I followed the mixing directions on the can. I then purchased a HVLP gun. I set the regulator at the gun handle to 30# (book recommended. I realize now that the pressure at the compressor was low and probably did not keep constant pressure at the gun. Orange peel again.

Is the HVLP gun capable of shooting acrylic enamel? What ratio of mix should I use?

A. To eliminate orange peel you need more volume. First, 30 psig on the compressor is not very high, and more likely you should have a pressure of approximately 50 psig at the handle of the HVLP spray gun. To preserve the volume of air, the air hose should be 3/8 inch and you should insure that you don't have more than one quick disconnect in the air hose, since QDs rob you of pressure and consequently also volume.

Under the circumstances you can try to reduce the volume of paint passing through the needle. Unfortunately, this might slow you down, but if you do cut down on the fluid supply, you might just have sufficient compressed air to eliminate the orange peel.

When purchasing a compressor, the psig output is important, but so is the volume of air. To operate an HVLP spray gun efficiently you should have a volume of approximately 15-205 SCFM, depending on the spray gun.

Good luck.

Regards,

Ron Joseph