I'm using Sherwin Williams 21 Polyester primer-surfacer on my fiberglass '34. Since this type of primer is a 1st cousin to the fiberglass resin, it's the right one to use . . . but, it's driving me crazy. I simply cannot get it to lay reasonbly flat. There's a slight orange peel to it that's really agravating. It's not hard to sand off, but I just shouldn't have to.

I'm using a DeVilbiss HVLP with a 1.8 tip. 23 psi in should give me about 10 psi at the cap, and I have a regulator right in front of the gun. I have a 7hp, 60 gallon compressor with all the filters, so I have plenty of good air. I've used this gun to lay down urthane primers, basecoats and clear coats - no problem. I used it to put the urethane primer on my '34 frame - no problem. However, I just can't make it work with this two-part catylized primer.

I'm not really looking for suggestions on how to spray this smoother, since I'm pretty well done with the last coat, and I've tried just about everything in the book (more air, less air, more distance, less distance, more fluid, less fluid, etc.) However, I'd like to know whether this type of primer is more difficult to spray than regular urethane primers.

. . . or maybe, I've just lost it.