Mixing can be a challenge. I've done enough of it over the years that it has become kind of second nature knowing what your gun likes, but I always use a large piece of cardboard to set my pattern and check viscosity. If it runs on the cardboard just add a little more paint and stir it in the gun cup. There is a range that will work, and while it's a little more effort, spraying with a decent gun definitely leaves a nice finish. I spray straight thinner through my gun after use, and totally disassemble and clean my gun inside and out. really only takes a few minutes, and I've been using the same old #7 Binks for 40 years. Mike