The present invention generally relates to a cleaning agent for a spray gun and a method and apparatus for cleaning the spray gun, and more specifically, to the agent and method of use thereof for cleaning a water-based spray gun using a novel cleaning agent comprising a solvent of n-butanol, a solvent of n-propanol, a surfactant of ethoxylated nonylphenol, and water. The cleaning agent may also be used under specific pH conditions and an emulsifier or a foam suppressor may be used. What is also contemplated is the use of a spray gun having smooth interior and exterior surfaces. The method contemplates the contacting of the cleaning agent with the spray gun, the recovering of the cleaning agent, the separating of the cleaning agent and the reuse of the cleaning agent. What is also contemplated is the use of the cleaning agent in an automatic washing apparatus and the use of the cleaning agent as part of a fluid supply to an automated spray gun to clean the spray gun access.