Brett;
So you sprayed clear dope over the finish on the fuselage, which was K&B/Hobbypoxy? Or was the fuselage dope? Just want to get this straight in my mind! Was it heavily thinned and lots of plasticizer? Like Flex-All?
Type at you later,
Dan McEntee
No. I finished putting the fillets on, the airplane was completely assembled and covered and I put one more coat of clear nitrate on it, from a new can, but labelled no-shrink nitrate, just like the can before. I put it on a chair, went to work. It was about 100 degrees, usual 10% humidity. I came home late that afternoon, as soon as I walked in the door, I could see a *severe* starved horse on the airplanes turtledeck. It was something lik 3/16" depression between the formers, 2" apart. This was a disaster, of course. I thought about how I could cut it off and redo it, but that would put me way behind. For once, I called Ted with a finish problem (which normally went the other way, like the 6 in the morning call asking about K&B thinner...). He suggested putting on another coat with plasticizer. I did that, with WAY more than recommended in a small amount of dope, because I had to loosen up maybe 6 coats of dried dope already on it. Put it on very thin ,and in about 15 minutes, it mostly went away. Then I finished over it as described, K&B Primer, etc.
So, after re-reading the earlier post, I see your confusion, but I would never, ever, use dope on the outside of the airplane. Clear dope is only uses to stick the silkspan or carbon on, after that, it is all synthetic material.
This was OK in most places, but once all the joints got steamed open on the bottom, oil got in, and since then it has been pretty much impossible to keep the paint attached for long. The primer/color/clear is intact, but the damn dope dissolves and then lets oil into the wood. I was keeping up with it OK for a long time, but once the stab got torn off and a big hole poked in the wing (when the airplane was flipped upside down onto my toolbox and fuel can), I more-or-less gave up.
Bottom line is that if you can at all manage it, just don't use dope aside from the most minimal applications, and don't use any Brodak products because (as many others have found) you have no idea what is in the can from batch to batch. I have no idea if the second can of supposed nitrate actually was, it acted like high-shrink butyrate. The later airplane uses SIG nitrate, just enough to stick everything down, followed by all epoxy or urethane. It is built the same way, same 3.8 LB A-grain, straight as an arrow.
I also note that in all cases, I was in a *massive hurry* both because it was right before the NATs (1999, 2006 and 2020) and also because I have to impose on my friends to do the paint, so I will do the best I can, but "fixes" are out of the question because that means someone has to put up with me again. So I put up with a lot of things other people correct in the process. Given that, I still manage a consistent 17-18 points, which is plenty good enough to keep me in contention on Top 20 day.
Other than the white yellowing a bit, the finish doesn't degenerate over time. I still have part of the the wing from the 1995 airplane, that is nearly 30 years, it is as good as the day I painted it, aside from being driven into the pavement.
Brett
p.p.s. The difference between what I described in the thread and what I did on the 2020 plane is as follows:
Carbon fiber veil instead of OO silkspan
SIG Nitrate instead of whatever was in the Brodak cans
Klass-Kote "fast" white primer instead of K&B primer. Klass-Kote is MUCH better, builds more, and took much less total mass
Klass-Kote colors mixed to Federal standard Red and Blue vice Klass-Kote "dark red" - covered vastly better with less paint
Difference in the quality - The carbon fiber seems to repel dings much better than silkspan. Keith Trostle just went to hold the 2006 airplane and just poked a divot into it just brushing his fingernail across it. This repair is nearly dead-center in the picture below, right on the top. You can't see it in the picture or in person. The 1995 airplane also had carbon, same observation.
I overestimated the coverage of the white, and there are a few spots where you can see things through the paint. The FS red (mixture of Bright Red, Dark Red, and some black) covered far, far better than the straight Dark Red, which was a nightmare and still took an amazing amount to get mostly opaque. The carbon lead to a fair number of pinholes and due to lack of time and being unwilling to impose further on my friends, I didn't fix any of them. To fix it, Bondo works very well, after sanding the primer, the holes will stick out like a sore thumb. Mix up Bondo, put a skim coat on with a soft plastic applicator, remove almost all. Let it set, sand back down, then just paint over it.
The clear was the usual PTG stuff that Jim also uses, can't complain about 2 20-point and multiple concours winners, same on 2006 and 2020 airplanes.
p.s. here is the turtledeck on the 2006 airplane, exaggerating the effect. It was VASTLY WORSE before the plasticized dope, and it hasn't moved since late June 2006. 18 points every NATs, missed the top 5 only once, won in 2006 (on only the 26th flight), second in 2008 by a hair. Aside from the shrink-wrap effect, the color and surface finish is absolutely front-row, at least on the top of the fuselage.
Topic: Paint process (Read 896 times)
