Length of coiled tubing A paint circulation system for supplying a paint mixture to a paint booth in an automobile manufacturing operation, the paint circulation system comprising a number of paint drop lines, the number of paint drop lines including a first paint drop line and a second drop line, the first paint drop line including a first color change valve for connecting a first paint spray gun assembly thereto, the first each paint spray gun assembly being operative to spray a paint mixture received from the first paint drop line at a first operative flow rate, the first paint drop line being positioned downstream of a first paint supply node and upstream of a first paint return node, the first paint drop line further comprising a means for generating a first differential pressure according to a first operative flow rate popular oil paintings, the means for generating the first differential pressure including at least one length of coiled tubing that is shaped to generate the first differential pressure, the first paint drop line being substantially free of any component or dead spot of sufficient size to cause accumulation of settled solids from a paint mixture to cause pressure changes to a degree requiring that the system be recalibrated or to cause settled solids to be deposited on a painted surface to a degree requiring remedial repair thereof. Wherein the first paint drop line is free of pressure regulators, pressure reducing valves, pressure gauge assemblies, tees, standpipes, isolation valves, isolation diaphragms, or a combination thereof, the second paint drop line including a second color change valve for connecting a second paint spray gun assembly thereto sunset oil paintings, the second paint spray gun assembly being operative to spray a paint mixture received from the second paint drop line at a second operative flow rate, the second paint drop line being positioned downstream of a second paint supply node and upstream of a second paint return node, the second paint drop line further comprising a means for generating a second differential pressure according to a second operative flow rate. The means for generating the second differential pressure including at least one second length of coiled tubing that is different than the first abstract flower oil paintings length of coiled tubing and shaped to generate the second differential pressure and is substantially free of any component or dead spot of sufficient size to cause accumulation of settled solids from a paint mixture to cause pressure changes to a degree requiring that the system be recalibrated or to cause settled solids to be deposited on a painted surface to a degree requiring remedial repair thereof, wherein the second paint drop line is free of pressure regulators, pressure reducing valves, pressure gauge assemblies, tees, standpipes, isolation valves, isolation diaphragms, or a combination thereof. Related articles: High quality painted product