Hi Bill,
Thanks for taking the time to share your experience with your TrueCoat 360 DSP. Spitting can happen for a couple of reasons but the best way to avoid that would be to strain your paint before you fill the cup (regardless of the age of the paint) and to make sure to clean the sprayer well after each use. If you have any further questions or issues, please don't hesitate to call our Tech Support team at 888.541.9788 M-F 7:30-5:30 CST.
-KR