auto primer question

Ready to paint my Olympic. All wood was coated with Nitrate. Then, wings and tail feathers covered with Silkspan, using LiteCoat to adhere the covering. Fuse was covered with carbon veil using litecoat. Open bays coated with three coats of Supercoat. Other areas covered with litecoat/thinner/micorballoon mixture and sanded.
If I use auto primer as my basecoat, do I spray over the open bays or not? I once used a dope/thinner/cornstarch solution over open bays and ruined a plane. Will auto primer sand easiy with 400 or 600 sandpaper without cutting through the silkspan?

Thanks, Mitch

Yes...

Reference Godzilla's autopaint method write up in the product review forum. Standard acrylic lacquer Grey primer (or something like rustoleum sandable grey)does sand easily. Cant figure out how you could ruin a wing by using dope and talc.

Dont know about the k36 catalyzed primers and sanding.

Put it on thin. sand it until it is nearly see thru or flat and then use a color blocking coat.

What do you plan to use for top coating?

I use K-36 mostly and it is very easy to sand. Sand until very thin, but try not to sand through. A lot depends on what you're going to use for color and clearcoat.

Sig/Brodak dopes for color and Matrix two-part clearcoat are my plans.

m,

I'd stick with a dope based filler if you're going that way. Maybe Zinc Sterate or similar. Even talc. Your likely to maintain better compatability. I've had trouble putting dope over K-36. It seems that you can put K-36 over just about anyting, but stuff that goes over K-36 needs to be compatable. The Brodak colors would probably cause a problem.

You might consider non-catalyzed urethane auto colors instead of Brodak. then you could use K-36 with urethane auto color and the Matrix over the top and maintain reasonable compatability.

LAST EDITED ON Aug-14-03 AT 07:47 AM (CDT)
 
I agree here...dont use the auto primer if you intend to us dope for color. My experience is the dope will lift the primer..even if it doesnt at first, any repair will be a problem. I suspect the clear over dope colors will be fine. It is like puting clear over a nice lacquer job.

This (lifting) is probably not the case with the k36 but adhesion problems are just as bad.

FWIW

LAST EDITED ON Aug-14-03 AT 10:26 AM (CDT)
 
Cap,

Exactly right. Don't put any sort of lacquer over K-36. It might be OK, but probably not. My experience is that putting dope over urethane, even catalyzed urethane will get you crinkles, lifting and all manor of uglies. It's fine to use dope up to clearcoat and use a catalyzed urethane for a topcoat, but mixing and matching is just asking for trouble.

I'm just finishing up some new elevators for my PA plane (don't ask ). From bare wood I used Polycrylic 2 coats and sand - K-36 and sand- non-catalyzed urethane autocolor and just sprayed 2 to 1 catalyzed clearcoat as a topcoat. Everything compatable and it worked great. and I can repair it without worry about what is under or over what.

Well heck Mitch, I thought you had developed a new fangled way to automatically prime an inverted engine

Well, it's not quite automatic, Bob, but the way I've normally done it is to squirt way too much fuel into the intake or cover it and flip it about one time too many. Then, read magazine until model sits for a while and try to start it. Once in a while, I time it just right!

Mitch:
What was the deal with the cornstarch/dope/thinner? Should have worked fine with lots of thinner, plenty of dope underneath to adhere, and sand with say 400 or even 600 and go easy on the capstrips and edges.
Rustoleum auto primer wet sands pretty well with 400 used wet but never tried it on open bays. It seems pretty heavy BTW.
Suggestion: use $$kote on open bays and dodge the problem.