OOPS, What have I done?

Discussion in 'Painting Questions, Tutorials and Guidebooks' started by Dr. Wartenberg, Dec 3, 2010.

  1. Dr. Wartenberg

    Dr. Wartenberg New Member

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    #1 Dr. Wartenberg, Dec 3, 2010
    Last edited: Dec 4, 2010
    WTF?
    Can some one help me figure out how I went from this:
    [​IMG]

    Then a coat of flat clear, then drying like this:
    [​IMG]
    ???? GRRRR, I'm so mad right now!
     
  2. lesofprimus

    lesofprimus Active Member

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    Gotta tell us what steps u did leading up to this disaster.... Was there old varnish/glosscoat/flat matte prior to the "new" work??? There seems to be either some sort of interaction with compunds or ur paint was completely and utterly sh!t....
     
  3. otftch

    otftch Active Member

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    I've had that happen when the overcoat paint can had frozen or some other way gone bad. The paint and propellant have seperated, hence the whitish dusting.
    Ed
     
  4. Thorlifter

    Thorlifter Well-Known Member

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    Interesting "crackle" effect also.

    I would also lean towards bad paint/clearcoat. Too bad Doc. Fantastic looking plane too.
     
  5. JohnAnthony

    JohnAnthony Member

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    #5 JohnAnthony, Dec 3, 2010
    Last edited: Dec 3, 2010
    I'm guessing you used Tamiya Flat COAT instead of Flat Clear. Flat Coat is something you add to glossy acrylics to make them duller. You can't apply it directly to a model or you get exactly what's pictured - a silver frost when it dries. Unfortunately the only course of action now is to strip everything and start over.
     
  6. vikingBerserker

    vikingBerserker Well-Known Member

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  7. Airframes

    Airframes Benevolens Magister

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    I agree with JA. However, similar effects can be caused by the following, given that you are using an airbrush.
    Previous coat(s) of paint/varnish not fully hardened.
    Too heavy an application, and/or second clear matt coat applied before first has fully hardened.
    Clear matt varnish not fully stirred before use, allowing the matting agent to dry 'white'.
    Combination of all of these.
     
  8. Dr. Wartenberg

    Dr. Wartenberg New Member

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    #8 Dr. Wartenberg, Dec 3, 2010
    Last edited: Dec 3, 2010
    well, I got the plane all ready for its first coat of sealer. I used a flat clear spray can by Valspar, which I had just purchased that same night, so it was brand new. I shook the paint very well, and even held it in front of my small heater to warm it up a bit(the temp in my garage is about 60F). I hung the plane on a hook from the hole for the rear wheel. I sprayed the entire plane evenly with the first coat. I came back 1 hour later to check on it and found what you see in the second pic.

    Before, while painting the wings, I layed the light green coat, then glossed cleared them so i dont peel the light green when masking off for the next camo color. I noticed the crackled white coat is more on the flat dark green than on the glossed light green...

    notice the white is more noticable on the olive drab than the lighter green that has been previously sprayed with a clear coat:
    [​IMG]
     
  9. N4521U

    N4521U Well-Known Member

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    This is typical of spraying a chemically hotter coat over over another. Like lacquer over enamel. It happens all the time in automotive applications. I had a friend who had a '29 Ford sedan delivery painted in enamel when he bought it. Took it to a painter, wanted it painted Porche RED, lacquer! The shop didn't seal the enamel. Looked like an old piano finish a couple of days later. Had to strip the whole car!

    Tough mate, it was an absolute ripper before that top coat.
     
  10. Airframes

    Airframes Benevolens Magister

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    Yep. The matting agent and carrier has reacted with the matt paint, and I think might have been applied rather heavily. Spray cans are a sod to use on models, as there is no real control. They must be used in light coats. However, it would seem that the varnish itself is the main problem - in the UK, the 'Valspar' brand provide enamel, polyurethane or laquer-type clear coatings, so I'm guessing it's the same elsewhere. These will certainly react with acrylic paint finishes, and can sometimes do likewise with some enamel - based finsihes, if the paint finish is thin, or not totally stable.
     
  11. Dr. Wartenberg

    Dr. Wartenberg New Member

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    It looks very heavy where its cracked, but i sprayed it evenly. maybe it was a thin viscosity and pooled up at certain points... i dont know...

    Oh well, my anger has subsided, i put on the Rolling Stones, grab a beer, removed the antennas, handles and small delicate pieces to start stripping the paint to start over. . .

    Any tips on how to recover the detail from rivets and panel lines? just take a knife or needle tip and re-score?
     
  12. Airframes

    Airframes Benevolens Magister

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    First off, use an ammonia-based cleaner to remove the paint/varnish, if it's acrylic, or alcohol-based thinner. If the varnish is enamel/laquer -based, then you could try an appropriate thinner, but this will tend to make the surface very tacky and bubbled (the coatings, not the plastic). A relatively mild oven cleaner is better here.
    Best to rub down, use a scalpel blade or similar to carefully get any 'gunge' out of panel lines etc, then clean-up.
    If you're careful, you shouldn't need to re-engrave.
     
  13. Dr. Wartenberg

    Dr. Wartenberg New Member

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    I'll try some oven cleaner on a wing and see what happens...

    I work on old Cadillacs and have a bunch of cars stuff around, would brake fluid or engine degreaser work?
     
  14. Vic Balshaw

    Vic Balshaw Well-Known Member

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    Wojetk put me onto brake fluid for the Spit I did in the last GB, I had to strip back gloss enamel that had be painted on by the original owner, it worked reasonably well but I also had the gently scrape the really hardened paint off, this also meant some re-scribing was required as the kit had raised panel lines.
     
  15. Wurger

    Wurger Siggy Master
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    #15 Wurger, Dec 4, 2010
    Last edited: Dec 4, 2010
    For cleaning of these panel lines use a toothbrush with quite stiff hairs. Of course it works with the brake fluid. The kind of panel lines ( recessed or raised) doesn't meake any difference.
     
  16. Wayne Little

    Wayne Little Well-Known Member

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    OUCH....that looks rather nasty.....my first thought was the matt coat, possibly not stirred enough and going on too thick and concentrated....??
     
  17. Dr. Wartenberg

    Dr. Wartenberg New Member

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    #17 Dr. Wartenberg, Dec 15, 2010
    Last edited: Dec 15, 2010
    I managed to get all the old paint off with minimal loss of detail. some rivet detail was lost on the top side of the wings so i re-created them using small drops of glue from the tip of a needle all along the rivet lines.
    This is the first kit ive used a clear finish on, so I'm still learning here and there. I may have applied the finish to thick again, as there are small bubbles on the crosses on the wings...
    [​IMG]
    hopefully I'll be posting it soon in the finished section.
     
  18. Airframes

    Airframes Benevolens Magister

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    Looking good so far, and nice recovery. If you're spraying the clear coat, do it in even, thin coats, and never go back over an area until it has thoroughly hardened. All clear finishes are more susceptible to the pressure of a second coat, which, whilst not showing up in a paint finish, will show as depressions or bubbles in a clear coat once it has dried. This is emphasised by the colour beneath the clear coat acting as a background which is literally magnified by the clear acting as a lens.
    When spraying, keep the brush moving at a steady rate, in one direction, with minimal overlap, staring before the 'target', and finishing off 'target'. Wings are normally best done, if possible, along their span, and fuselage along the length, starting at the top, end to end, working down.
     
  19. Crimea_River

    Crimea_River Well-Known Member

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