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General control line discussion => Open Forum => Topic started by: Darrell Mims on November 27, 2006, 04:30:30 AM
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8) Has anyone else had a problem with priming a plane with Brodak primer ,then using Sig color dope over it ? I've seen on a couple of planes that when the color was sprayed over Brodak primer ,if sprayed too thick would attack it , make it wrinkle up . Then when it was drying it would smooth out .
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I believe that mixing manufacturers of dope isn't the hot set up...
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I only use one brand of dope from start to finish. I do not have any problems, except for the fact that it is either to cold or to humid to spray dope here in West Michigan.
Leroy
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So far I guess I have been lucky in that I have not had problems of SIG over Brodak or vice versa. Maybe you are spraying it to thick. DOC Holliday
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Using the same thinner in all your dope helps. If it is butyrate, it is not usually a problem as to which "brand" it is. The old Aerogloss didn't nix with Testors, but those are both gone now. (I have my firesuit on, flame away!)
ANY lacquer (and dope is a *lacquer*), and especially if you use a *HOT* thinner, will craze, or attack the layer you are applying it to if you put it on too heavy. Lacquer paint is a chemical reaction bond, so it must "eat" into the layer below it. If you get it heavy, and especially if you have a hot thinner, it will do as you have described.
I know I'm the "Blind Hog" with about everything I do concerning these models, but I use aotomotive lacquer, Sig, Randolph's, and a little Brodak, all on the same planes. After many years, it hasn't messed up yet!
Even use two part urethanes over dope bases and two part clears over dope colors................
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Leroy,
I LOVE to spray dope when it's "too cold"! I simply make sure the dope and the target (airplane in this case) are both at room temp inside before going out to the outer shop to spray. The dope really doesn't care about room temp as much as it does the target temp and by the time you have a coat sprayed on it has started to cure already before it's "chilled" too much for proper chemical reaction.
I've done it this way for over thirty years including recovering full scale airplanes and have never had a temperature induced problem. The rerason I love it this way is because there is no way I can get the dreaded blush in the winter if I properly filter my air supply. Not so in the ehat/humidity of summer. (Besides, I'm flying in the summer!) Wish I could say the same for other problems with finishes! Like fillets?
Blessings,
Will #^