no one has said a thing about air pressure I spray vinyal paint, but if the air pressure is to high and I thin to much it will spit and splatter because it pushs air past the paint and starts to dry and plug the tip. I may have missed if you said what the air pressure is but you need to lower it as you thin and for detail work, and if your air is comming from a hot compresser it can cause plugging from dring at a high rate before the paint can leave the brush.