I have a report for you guys about this primer. I just finished sanding my Ringmaster completely after applying this primer. I used 400 grit on the solid balsa surfaces and 600 on the open bays (the wing was covered in Polyspan) and I have NEVER EVER had that smooth of a surface ready for paint since I have been building. It dried in minutes but I waited an hour before I started sanding. Before you sand if you run your hand over it, the surface feels kind of gritty but when you start sanding it smoothes out to a slick smooth surface. I cannot remember having such a smooth surface getting ready to paint.
Note: Here is how I did the preparation on the solid balsa surfaces and On a Ringmaster that is everything but the wing.
I sanded all solid surfaces as smooth as I could ending with 400 grit.
I then took Minwax Polyurethane right out of the can and brushed two coats of it on the surfaces, letting it dry overnight between coats.
I then sanded all the surfaces down as smooth as I could get them.
Then I took some Dap Vinyl Spackling compound and mixed it with enough water in a glass to get a consistency of Pancake Batter. Get it as smooth as possible.
Brush a coat of this on and let it dry good. In the summer outside it will dry quick. I have applied a second coat in as soon as an hour.
Sand the first coat smooth and then apply a second coat of this slurry and let it dry.
Sand again as smooth as you can get it. I usually start with 180 grit, go to 220 and then to 400 for the final sanding.
Then spray your primer (NAPA COLORLINE) and sand it as I explained above.
Paint with anything you want to paint with. I will probably use Duplicolor and spray a urethane clear coat over that.
Mike
Oh PS...I covered the wing in Polyspan and applied the first coat of Nitrate dope right out of the can and did not thin it. The second and third coats were thinned 50/50. I lightly sanded with 400. Then I put two filler coats of 50/50 dope with zinc steerate and then sanded again LIGHTLY with 400 and applied my primer. Sand the primer with 400 or 600 grit. I did the edges and the center sheeting area with 400 and the open bays with 600 and as my grandpappy used to say , "It is slicker than a minnows peter." Thats an old country saying..