Sounds like you do need another water trap on your line.If it is an acrylic laquer (and not a water based acrylic) or an acrylic enamel, you can only use the solvents that are designed to reduce them.You cannot use any water based reducers or thinners.It won't do anything but cause a huge mess and an even bigger headache. There are a number of things you can use to reduce water based acrylics. However, almost always you should use the thinners that were made specifically for them.It typically isn't wise to mix and match.You also pretty much want to stick with "ONE KIND OF PAINT" . Its one thing to start with an enamel or laquer primer on your model, but after that you need to decide on using either a water based acrylic like Tamiya,Testors,Model Master,or artist grade acrylic;or an enamel like testors,Model Master, Humbrol etc or some other paint. If you bounce between different paints and brands, due to chemical incompatibility you are possibly setting yourself up for a monstrous disaster.However, basically you are safe as long as you stick with one kind of paint, so if you are using enamels, you can apply between dried/cured coats (but I advise not to custom mix between brands for the above reason mentioned).You can typically thin water based acrylics with distilled water (reccomended) as all the impurities are out of the water.Some folks will do a 50/50 mix of H2o&99% rubbing alcohol and thin their paints a good 25%-30%. There is a fudge factor with most acryics, and you can use the an airbrush medium like Liquitex's with most acrylics I imagine.Advice I have been given was to mix airbrush medium with distilled water 50/50 and then you can greatly reduce your acrylic paint.More than 25% I was told...possibly up to 50%.The airbrush medium has *acrylic* in it, so instead of just thinning with water and over diluting the paint, you are not messing with its chemical or structural properites as much.Sounds complicated, but not really.Windex has been used and many times some folks will add a drop of liquid dish soap to a thinned and mixed bottle paint.The soap reduces the surface tension of the water in the paint.As they say, there is always more than one way to skin a cat but there are some things you do have to keep in mind concerning airbrushing.