Where did I go wrong? splotchy, not-drying

[chang-kuao-lo]

I was attempting to paint some modelflex super gloss black on to my madmax interceptor, with an aztec a430 at about 15psi, with the general purpose (gray) nozzle. I had the paint thinned to 10:1 with dH2O, the surface was primed with G-S mr. surfacer 500 which had been long since cured. The first coat came out splotchy, almost like a leopard-skin pattern, as though the surface was contaminated with oil. I cleaned the surface off with some ammonia windex, and tried again after it had dried, a little better (not much) and with little bubbles appearing in the paint, and it did not seem to want to dry between coats. In the end, it looked like hell. I cleaned the whole coat off as best I could, and would like to try again if I can find out where I went wrong.

I previously used the same set-up with G-S flat black thinned about 10:1 99% IPA, and it worked beautifully, I couldn't have been happier. I have a tank-style compressor with a moisture trap which seems to be doing its job. The super gloss black seemed to spray quite nicely on the cardboard I test it on, no luck on the model. Could there be a non-compatibility issue with modelflex and mr. surfacer? Or is this not the best paint, or is my technique faulty? Too much/not enough thinner, pressure? Could one make a basecoat of future for a better surface? Any help is greatly appreciated.

[macfrank]

The distilled water may be the problem. The paint's surface tension may be causing it to bead up when it hits the model. Use a very, very small amount of liquid soap (or Photo-Flo, if you've ever done film developing) in the water, go back to either isopropyl or denatured alcohol, or use Windex/windshield wiper fluid (it has some soap/alcohol in it).

[roguepink]

Using a water based paint, you can also try Testor's Acryl thinner.

If the surface of the model is too smooth, paint may bead through surface tension.

As my general rule, I thin my paint to a 3:1 for flat or 2:1 for glossy, favoring the paint.

Third, step up your pressure to 20 - 25 psi. Too low a pressure setting will not properly atomize the paint in the air flow. 10 psi is far too low to get good results, especially with a gloss paint.