I figured out a few things when I primed my plane with Smooth Prime.
First, sand it with 3M Sandblaster paper. This stuff is incredible. It does a great job, takes forever to wear out, and most importantly, it doesn't clog like all the other sandpapers I have used. I used 150 at first, then switched to 220 on the primer. I also use the Sandblaster paper on everything else I sanded with equally good results. The other thing I figured out, of course on my last few parts that I was priming, is that you have to get rid of the bubbles before the last coat of primer. The reason you get pin holes is because there are small bubbles in the primer. The bubbles never pop and you wind up with a small crater with a very thin dry bubble top on it after the primer is dry. If you just put another coat on top of it you still have the bubble underneath. You can put on five coats, but as soon as you sand you take off the tops of the bubbles and are left with the craters. Then you have to sand all the way down to get rid of the craters and of course you take off all the primer doing that. What I did that worked very good is to roll on as many coats as I needed minus one coat. After it fully dired I sanded just a little bit with 150 paper to get all the bubbles popped. Then, very important, remove all the sanding dust and go over the surface once with a tack cloth to make sure all the dust is gone. They you apply one last thinned coat. The last thinned coat fills the craters so you have a lot less sanding to do when you are done. I suppose that you could try sanding a little every other coat, or the last two coats, but I was almost done when I discoverd this and sanding just before the last coat worked very good for me. One other thing I tried when I was out of primer and had just a few very small scratches to fill was to take a bunch of smooth prime dust, mix it with water, then roll it on. This was a failed experiment. It just turned back to dust after the water dried out of it. I guess that there is some right solvent that can make dust back into usable primer again, but I don't know what it is. Dan Heath wrote: I have applied this stuff for the last time. I have almost removed, almost all of it for the last time. Better than 95% of it will end up in my Shop Vac. This stuff creates more pin holes than it fills. I now remember why I didn't like it when I applied it to the bottom of the plane, over a year ago I may try an experiment with the remaining stuff by thinning it out so it will flow and see if it does any filling, but other than that, this is way too expensive to send to the trash pile. It took me about an hour to apply 16 oz of it and I have over 2 hours in sanding it off. You can't wet sand it so the dust it terrible. The bottom line for me with UV Smooth prime is a big thumbs down.
