How long can paint be left in an airless sprayer?

How long paint can be left in an airless sprayer depends on paint type, temperature, and how you store it, but general guidelines help prevent clogging and damage to expensive pump and hose. For water-based latex paint, if you leave pump submerged in paint bucket, relieve pressure, and seal gun and tip with damp rag or plastic wrap to prevent air, you can leave paint in airless sprayer for up to 12 to 24 hours overnight and still spray next day without cleaning, which many pros do on multi-day jobs. However, beyond 24 hours, latex can start to skin, thicken, and clog tip, filter, and pump, risking damage. For oil-based paints and primers, you can leave overnight similarly, but longer than 24 hours increases risk of gumming. Manufacturers like Graco recommend cleaning if you will not use sprayer for more than 24 to 48 hours, and for long-term storage, you must flush with water for latex or mineral spirits for oil, then pump storage fluid or Pump Armor to protect pump. Leaving paint for several days or weeks will cause paint to cure inside pump, hose, and gun, requiring expensive rebuild. So short term overnight is okay with precautions, but for more than a day, clean sprayer thoroughly and store with storage fluid.