I have recently purchased paint to repaint the exterior of my house. It's Valspar Duramax Flat Latex for exteriors. It is extremely thick. It causes my Wagner 220 to sputter and clog up. Should I thin the paint down (which I'd prefer not to - but if I do what do I use and how do I do that) or can I change the size tip. I have the spray tip that came with it (Pink 0.8mm) and if I don't use this - what size would I use. Thanks! Martha