Paint "crackling" over future?

You're welcome!

Old paint may settle, leaving a clear resin/solvent over the pigment. If the pigment can be redispersed adequately, the paint may still be useable. If, on the other hand, the paint seems even faintly ropey or stringy, just throw it out. It has started to polymerize in the jar, and even if you seem to have dissolved it in solvent, it will never perform properly. This applies to both acrylics and organic solvent systems. It does not apply to true lacquers.

Paints have different shelf lives. Shelf life is strongly dependent on formulation, and formulation is a trade-off process. Producing an accurate color, good bond to substrate, acceptable cure time, proper degree of gloss, hide, flow, etc. not to mention economics, all govern formulation. Shelf life is low on the list—the paint has to be at its best when opened. If it's no good five years later, that may be quite acceptable. Very few paints are formulated to have a shelf life that long, especially after the container is opened.

Hmmm, Thanks Triarius, thats good to know.
 I used Windex and removed all the old paint, It's back down to the plastic now (not exactly an easy feat considering the Future had a week to dry and there was 3 layers of paint, hehe).
 
 But reading what you have posted leads me to believe one of two things has happened. The paint was old (it was pretty thick in the jar), and therefore I had to thin it too much, and/or the combination of the two lead to the crawling. The crawling started as the paint started to dry, it wasn't instant, but happened pretty fast.
 The temp. was constant. I painted in my house, the same place everything else had been painted, without any adverse effects before. Also, I was using all Model Master paint and thinner, so I don't think it is a compatability issue.
 Thanks for all your input. It is really apreciated, so I can figure out how not to let it happen again.

Cracking, or "alligatoring" "snakeskin" or crawling, as it it properly called, is usually caused by poor bond between the paint and the substrate.

In your case, this could result from:

1. Something on the surface of the Future that interfered with the bond.
    Clean surface.
    Dry surface—even the slightest amount of condensation (less than you can see) will interfere with paint adhesion. Was the model colder than the surrounding air, or was the room relatively cool?
2. Poor adhesion of the overlying paint. This, in turn, can result from:

1. Fundamental incompatibility between paint and substrate—the paint beads  up before it dries.
2. Incompatibility of paint and reducer (thinner) used for spray dilution. This causes the paint to

partially cure before it hits the surface, or
causes the paint to shrink more than normal when it dries, or
interferes with coating polymerization, causing increased shrinkage or weaker resistance to shrinkage cracking.

    Check compatibility of reducer with paint.
3. Rapid loss of reducer, reducing initial paint adhesion. This usually causes dusting, but  can also cause crawling.
    Increase proportion of reducer, use slower evaporating reducer, increase relative humidity.
4. Partial polymerization of the paint in the container—was this an old jar of paint?

That's all that comes to mind at the moment. If I think of anything else, I'll post it.

Hmmm, interesting.  I could only really see the paint cracking from that if it was put on really thick or something, still that's odd.  Never seen that happen before.  Good luck with getting it "fixed".  :)

O.K., I showed the crackling paint to a friend and he instantly said "Oh, your paint dried too quickly, how much thinner did you use?", so I can assume I found out what caused the negative results. I'm on my way out to get some Windex now (the glass cleaner I have here is amonia free,lol). I'm still not sure about the paint drying too quickly though. Seems a bit odd, but it did crackle worse in the areas where the paint was less thick.

Just be careful that you don't get the Windex where you don't want it.  I accidentally had a little on my thumb when I picked up my FW190 the other day, put some nice fingerprints on the rear deck of the cockpit.  No biggie though, a couple of cue tips, windex and some careful cleaning got the paint off, then I repainted it.  Works great!  :)

private thud wrote:

Ahh Windex!. I had heard of using it to clean up Future, but never thought of using it to clean this up. Thanks for the tip.

If you soak it in Windex, most, if not all of the paint will rinse off—I just did that with my paint hulks.

Ahh Windex!. I had heard of using it to clean up Future, but never thought of using it to clean this up. Thanks for the tip.

Hmmm, not sure what the deal is there.  I haven't had that problem.  The only thing I can think of is maybe the MM thinner "dissolved" the future a bit?  I know when I "mess" up a paint job with acrylics I use some windex, Q-tips and a soft cloth to take it off.  The amonia cuts right through the acrylic and makes it very easy to gently wipe the paint off the model.