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Author Topic: Dope finish -- painting after flying  (Read 869 times)

Offline Tim Wescott

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Dope finish -- painting after flying
« on: August 15, 2021, 03:48:14 PM »
Can I get away with finishing a plain out in white, then flying with a nitro engine, then bringing it home and doing the final finish?  How much more work is it to finish a plane that's had castor slobbered on, and how much risk is there to paint adhesion?

The NW Regionals is two weeks away, and I have this plane -- and a day job, so I can't just spend the next ten days working on the plane.  I might be able to get it into white paint, but no further -- I'd like to compete it for what I can get this year, then finish it out over the winter.
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Offline Dan McEntee

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Re: Dope finish -- painting after flying
« Reply #1 on: August 15, 2021, 09:34:34 PM »
  Jack Sheeks mentioned many time sin his articles that he would get a model finished up to the point of all the clear build ups done, then test fly the model. Then if there was a major issue that meant that he needed to cut into the model, then it was easy to patch up before the final finish. He told me once that he did the pattern on the first flight of each one also. If it wouldn't do it then there wasn't any point in continuing!! If everything is doped up properly, I don't see  why a few test flights would leave that much on the top coats. A good wiping down with some Prep-Sol, a light over all sanding and another wipe down with some solvent and you should be OK. 5 or 6 flights, but maybe not 50 or 60!!
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Offline Tim Wescott

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Re: Dope finish -- painting after flying
« Reply #2 on: August 15, 2021, 10:06:49 PM »
Thanks Dan -- I seem to remember reading something like that.

It's a scale plane, and the Northwest Regionals is Labor Day weekend.  So I'm thinking I'll squirt white on it, put it together, and assuming that it test flies, go to the contest.

Barring bad things during test flights, it'll be maybe ten flights, tops, then it'll be back in the shop for color.
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The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline kevin king

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Re: Dope finish -- painting after flying
« Reply #3 on: August 19, 2021, 06:27:11 PM »
Sounds high risk to me. Color paint is porous. Best to seal it with a 2 coats of clear at the least.

Offline Brett Buck

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Re: Dope finish -- painting after flying
« Reply #4 on: August 19, 2021, 09:09:27 PM »
Sounds high risk to me. Color paint is porous. Best to seal it with a 2 coats of clear at the least.

  His dilemma has been resolved, thanks to extensive wildfires in CA and OR.

   Brett

Offline PJ Rowland

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Re: Dope finish -- painting after flying
« Reply #5 on: August 20, 2021, 06:18:04 AM »
To answer the question.

Theoretically... you could do it..

But you would need to 100% guarantee you were able to get all the oil residue off the entire plane and I suspect that to be very difficult. The main issue is going to be the airframe will fly through exhaust residue.. oil is really hard to remove completely.

For the effort, I wouldn't bother.

Pyromania is/was probably an extreme resolution to this issue, perhaps you could have just not flown it?


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Offline Tim Wescott

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Re: Dope finish -- painting after flying
« Reply #6 on: August 20, 2021, 09:10:22 AM »
  His dilemma has been resolved, thanks to extensive wildfires in CA and OR.

   Brett

Unfortunately, yes.  The NW Regionals is the only CL scale contest of the year.  So I now have until May.
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The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Dan McEntee

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Re: Dope finish -- painting after flying
« Reply #7 on: August 20, 2021, 09:47:07 AM »
Unfortunately, yes.  The NW Regionals is the only CL scale contest of the year.  So I now have until May.

       You know what the other Murphy's law is, don't you?? " All work expands to fill the time you have to complete it in!" That means that you need to finish it as if the contest were being held, or you may end up having to rush it next year!!
    Type at you later,
    Dan McEntee
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Offline Tim Wescott

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Re: Dope finish -- painting after flying
« Reply #8 on: August 20, 2021, 10:10:52 AM »
       You know what the other Murphy's law is, don't you?? " All work expands to fill the time you have to complete it in!" That means that you need to finish it as if the contest were being held, or you may end up having to rush it next year!!
    Type at you later,
    Dan McEntee

That's my plan.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Avaiojet

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Re: Dope finish -- painting after flying
« Reply #9 on: August 20, 2021, 10:20:13 AM »
That's my plan.

You could spray the entire model with an automotive 2 part primer of any color than what the model currently is.

Fly the thing and generously clean the nicks and crannies.

Repeat the cleaning every time you fly it.

When you're ready to finish the model, simple sand away the top color primer. This could work as a "tracer" coat as it was once called, now they, there's always a they, they now call this a "guide" coat.

Might also help in finding imperfections.

Just a suggestion.
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Offline MikeyPratt

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Re: Dope finish -- painting after flying
« Reply #10 on: August 29, 2021, 01:42:54 PM »
Hi Tim,
Iíve done that a few times and it worked out pretty well on the repaint.  But you have to make 100% sure the wood and tissue are filled completely before flying it.  After flying it, I would rub the model down with solvent (Maxy Hester airplane cleaner or Mineral Spirits).
 
Then scrub it with Windex and paper towels at least two or three times to make sure it clean.  Lightly sand the model again, then spray on 1 or 2 more coats of dope.  The reason for spraying two more coats was to make sure you donít have a reaction when adding the sanding sealer or color coats.

Later,
Mike Pratt


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