Can anyone help,I am having trouble getting a decent paint flow from my airbrush. When I think I have a good mix,paint spits out in splotches, so after a few drops of thinners all I get is watery tinted paint spraying out. I mainly use Humbrol enamels

Not knowing what kind of brush you have,but it sounds like a dirty tip,might need to be disassmbled and thoroughly cleaned.

Often I have noticed that if the brush sits too long with paint, even a few moments, it can develop clogs and cause it to sputter. Sometimes cleaning the tip with some proper thinner works, or removing the nozzle and giving that a thorough cleaning every so often works too. Hope this helps. Cheers,

Another possibility is that you have water, in your system.

I used to get the same problem. I was using water to thin the paint. After switching to thinners I no longer get irregular flow from the AB. And of course make sure your AB is clean.

since you said you thinned with water, let's assume that's an appropriate thinner for your paint (acrylics). I would add some alcohol or windex to the paint--not just water. That helps it flow better in my experience. Keeping the tip clean is very important and often troublesome with acrylics since they dry so fast.

If you're using tamyia paints, you may try thinning with lacqure thinner. That helps some. If you're using testors acrylics, STOP. I've never been able to make them work with any airbrush, ever. As someone else suggested, you may have water in your system somewhere, probably from the compressor. I'd add a water trap of some kind to the hose.

There's also a chance that the issue is not just the consistency of the paint but how you're applying it. If the pressure is too high or you're too close to the model, this will cause it to run, even if it's perfectly thinned. You may also try applying a primer coat from a rattle can. Often the very slick nature of plastic makes otherwise eel-mixed paint to run. There's ways around this (such as spraying from a greater distance, 'misting' the surface, to get some grit, etc) but a good primer coat goes a long way. You may find that, after the primer, you're paint lays down just fine. One last thing to keep you from ruining your models, test your spray on some scrap first. Not model boxes or paper towels as they suck up moisture and can be deceptive. Get some old/cheap models and test your paint on them first. That'll save a lot of frustration. Truth is, though, there are so many things that can go wrong (and right) when spraying paint, even the best of us sometimes get frustrated! Just keep practicing. Soon you'll learn what paints work best in what consistency at what pressure for your airbrush.

Hope some of this helps.

EDIT: I reread your post and saw that you're using humbrol enamels. My first two thoughts here are 1) If you're not already, use humbrol's thinner, at least until you figure your mix out. That'll remove one more variable. 2) make sure the paint is thoroughly mixed in the bottle, and then in your paint cup.

The other suggestions about your spray technique and water in the line apply all the same.

Thanks everyone for your responses and help. I will try your suggestions and post my results. JU-88 with splinter camo on my workbench