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        Discussion Paint over Dope ???

#1 ledpole Jan 21, 2013 10:12 PM

Paint over Dope ???
 
have the opportunity to pick up an older plane that the current owner also purchased used but never finished. It currently has a primer dope finsih. No idea of type of covering or type of dope used. Is there any paint on the market I can safely use. The plane is wood construction. Prefer rattle can or air brush if necessary.

Thanks

#2 Wolpertinger Jan 22, 2013 10:12 PM

By "Primer Dope" do you mean clear dope? It would be good to know if it was nitrate or butyrate dope. Almost any type of paint can be applied over nitrate. Butyrate can be a bit fussier, but I suspect that you won't have any problems airbrushing almost any type of paint over top. Even with rattle cans, I think the only ones you might have a problem with is automotive lacquers. Test a small patch and see.

#3 kenh3497 Jan 23, 2013 12:39 PM

I may be wrong here but I think.... Automotive lacquer should be one of the first choices. Dope and lacquer are kind of in the same family as both are solvent based. I would just make sure the dope finish is well sanded and very clean. Try some rattle can lacquer on the bottom of the fuse, ( a small patch) and double check for a reaction. There should be none. If all is OK then spray away. Sand off 99% of the first coat then re-spray a light coat just enough to cover. VERY lightly sand and shoot on your color.

Ken

#4 Wolpertinger Jan 23, 2013 01:12 PM

Quote:

Originally Posted by kenh3497 (Post 23905015)
I may be wrong here but I think.... Automotive lacquer should be one of the first choices. Dope and lacquer are kind of in the same family as both are solvent based. I would just make sure the dope finish is well sanded and very clean. Try some rattle can lacquer on the bottom of the fuse, ( a small patch) and double check for a reaction. There should be none. If all is OK then spray away. Sand off 99% of the first coat then re-spray a light coat just enough to cover. VERY lightly sand and shoot on your color.

Ken

Exactly, they are of the same solvent base, which may, and I stress may, eat into the surface of the clear dope and cause crazing. But if it doesn't, then it's good to go. As you said, try some light coats first. It always pays to test compatibility first.

#5 kenh3497 Jan 23, 2013 07:26 PM

Quote:

Originally Posted by vonJaerschky (Post 23905345)
Exactly, they are of the same solvent base, which may, and I stress may, eat into the surface of the clear dope and cause crazing.

That is one of the beauties of lacquer paint. The following coat will slightly soften and bond to the under laying coat. You always , well, almost always;) have a perfect bond. I would not expect lacquer over dope to cause any problems. The other way around though I would have more concern.

Ken

#6 edwin1 Jan 29, 2013 09:04 AM

I sprayed warbird colors over a doped fabric covered cub. Worked fine. But this was his old formula. I hear his supplier changed formula and he's having to change some things. Last I heard he doesnt use the catalyst anymore and recommends you use a clear coat, which I usually do anyway. Nelsons would probably work too.
Edwin

#7 Jack1950 Feb 04, 2013 12:22 PM

Paint over dope
 
I've just purchased a refinished airplane that was supposedly recovered and painted with a butyrate primer on the fuselage and clear over fabric on the wings. This had been done quite a while ago so the dope finish was well cured. I painted the entire airplane with spray cans of indoor/outdoor gloss "Krylon" paint, red fuse with tan wings, and it seems to have adhered real well. Also, rubbed some raw nitro fuel on it and doesn't seem to bother it. If any future problems arise with the paint adhering to the dope or with softening from the fuel I will repost and pass on the info. The "Krylon" didn't add much weight and is a quick dry paint.

#8 edwin1 Feb 04, 2013 12:59 PM

Most of us use rustoleum, we know it is fuel proof. Some have reported that krylon is not fuel proof. Just an FYI. I dont know how new you are to rcg but I would suggest a search on krylon here on rcg and see what others say. This is just my opinion and someone else may have found a way to make it work.
Edwin

#9 TomCrump Feb 05, 2013 07:56 AM

1 Attachment(s)
Quote:

Originally Posted by edwin1 (Post 24031717)
Most of us use rustoleum, we know it is fuel proof. Some have reported that krylon is not fuel proof. Just an FYI. I dont know how new you are to rcg but I would suggest a search on krylon here on rcg and see what others say. This is just my opinion and someone else may have found a way to make it work.
Edwin

I'm with you on using Rustoleum. It may dry slower, but I feel that it is a far superior product, for our usage, when compared to Krylon.

#10 buzzard bait Feb 16, 2013 05:10 PM

I don't think you can trust Rustoleum. I think the formula must change, or vary between colors. Some report excellent results, but others get problems. I wound up with a mess using Rustoleum downstream from the exhaust, and that was after it had cured for a couple of weeks.

#11 TomCrump Feb 17, 2013 07:31 AM

Use what you are comforable with.

I haven't experienced problems with Rustoleum. That is why I suggest it to others.

After 30+ years in the paint manufacturing industry, I can tell you that I have never seen a formulation change, for different colors,, in the same product line.

There are many variables in a paint's performance. Surface prep, application, and cure time, are just a few. Get something just a little bit wrong, and problems can arise down the road.


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