Well I bought a athearn model last week and I put it together and got out my airbrush to give it a quick weathering job this weekend, but ran into some problems. I use the Floquil Polly Scale water based paint. I haven't had my paint out for a couple of month and I made sure to mix it up well. I put a little airbrush thinner (the kind for floquil paint) in a jar then put some paint in with a dropper. Once I got my dropper cleaned out I was heading over to start airbrushing and noticed the paint had clumped all up onced mixed with the airbrush thinner. After retrying because I thought I had a bad mix it happened again and I had even taken a panty hoe and strained the paint first thinking I had dry chunks in it. The pigment still seperated. So I proceded to do 100% straight paint to airbrush and it got the job done, but has my paint went bad or is it the thinner? My dullcoat I used wasn't floquil and it mixed with the thinner alright. I use Model master dullcoat.