Wha' Happen'

[ShutterAce]

What did I do?

Base colors are Tamiya thinned with ISO. ID band is PollyScale thinned with Future. The base coats were sprayed a year ago. ???

 

[Glorfindel]

Temperature and perhaps even humidity is my first guess. If it's dry and warm in the room where this is kept it's possible the paint will shrink and crack. After all even DaVinci's works have been restored. Heck I have molding on my ceiling that the paint has cracked due to temp and humidity. I think that's your answer. Maybe even the mix of Polly Scale with Future created an unstable bond thus rendering the combination susceptible to cracking over time with changes in the surrounding environment. Plausible.

 

[ShutterAce]

I dunno. I painted that stripe today and it has been raining off and on. The cracking appeared within minutes of application. And like I said, I know that Tamiya paint is cured.

This is the second time lately that I have had this problem. The last time it was Alcad over Walmart gloss white. that gloss white had been sitting for over a year too. :-\

 

[ScaleModelMadman]

Due to the fact that the base coat had been sitting for so long, I would have to say it's not a case of the underlying paint still 'gassing out' through the top layer.

I have to wonder if it's a reaction between the pollyscale and the future, like perhaps one drying faster than the other. I also wonder if it was just applied too thick, too fast?

I would think about re-masking and maybe filling the cracks with filler, then re-spraying with thin misted coats allowing each to dry a bit before applying the next?

 

[WayneBt]

If the Polyscale paint is flat then the Future and the paint have 2 different drying times. Even when mixed they would dry at a different pace and the paint would crack. I know from experience that if a flat paint is painted over top of a gloss coat the flat paint will crack.

 

[ShutterAce]

I think you're on to something Ken. I brushed this and it was two coats. The second one went on as soon as the first one flashed off. They were a little thick too.

WayneBT, I'd have to do some experiments but I have been spraying PollyScale thinned with future for a long time and I'm not the only one. You end up with a semi-gloss finish but it works just fine usually.

 

[Dusky]

I wouldn't mix different brands of paints. Even among the same brand paints can have subtle differences in formula. Pollyscale sprays so well thinned slightly with distilled water. I don't know why you would want to thin it with Future.

 

[fumblethumbs]

On the upside Jim, if this could be figured out and contolled, it would make for a great technique on a dilapidated house or other structure!

 

[ShutterAce]

Spit', all I can say is that that was the advice given to me when I Started using them and it has worked fine


FT, you just may be on to something there.

I have sanded and put two more coats on and it worked fine. Who knows.

 

[Dusky]

It's likely due to the mix of two paints not being fully mixed and drying at different rates. One of the paints may be past its prime. The other problems that could cause that are shrinkage/expansion of the material the paint is applied to or absorption of the substrate/solvent by the substance underneath, but they don't seem likely in this situation.

 

[Chris S]

I think you're on to something Ken. I brushed this and it was two coats. The second one went on as soon as the first one flashed off. They were a little thick too.

I think you answered your own question there Jim . The first coat was in the proccess of drying (shrinking) when you applied a fresh coat .I have seen this happen before when brush painting . But like you I also mix some Acrylics with Future /Klear and used through the AB its not a problem because it dries nearly instantly

Chris.