Problem with Tamiya XF-1

Sounds like contamination of some sort. I don't think it's an age problem, as I have some Tamiya acrylics which are in the 25+ years old range and they are still going strong.

What did you thin the paint with? Please don't say tap water.

Water/moisture in the air hose perhaps? Or remnants of enamel thinner in the airbrush? 

PS: XF-1 is flat black

Oops...I meant Flat Red...I used distilled water....I have been thinking all evening about it an realized I usually use Tamiya thinner or ISO.  I have both on the shelf.  I guess I wasn't thinking....thanks for the response.

Ahh, ok. I find that when you thin Tamiya with water of any description, the paint tends to separate and you get a whitish scum on the surface. If you lay down the paint heavily and it starts to pool on the surface. it will often separate again and it looks like swirls of dirty scum on the wet paint.

Would that be a fair description of your problem?

Bingo....It was chalky overall and there was separation in many places.  Again, I kicked myself for making such a rookie oversight. But you are spot on.

I started my corrections by sanding with some really fine sandpaper.  Washed it down and it is ready for my second round of pre-shading and base coat. 

Thanks for the attention on this.

You're welcome Hutch.

I hate it when so simple a mistake makes things go so wrong. I once picked up a squirt bottle of water inatead of alcohol to thin some gloss white Tamiya acrylic. It took hours to dry and dried with an eggshell finish...