696 Section 5 Refinishing Copyright Goodheart-Willcox Co., Inc. brush to clean the air cap and fluid tip. If the orifices are clogged, use a toothpick to remove dried paint. Never use a metal tool to clean the orifices as this may enlarge the hole. Remove the needle and wipe it with a thinner- moistened rag. See Figure 28-43. Use a brush to clean inside the inside of the paint tube. A dirty spray gun may require fluid tip removal and brushing the entire paint passage. Clean the threads of the paint cup and lid with a thinner-moistened cloth. Rinse the spray gun with thinner. Only the portion of the spray gun that holds or carries paint needs to be cleaned. The cleaning thinner is hazardous waste, so minimize the amount used. A siphon feed or gravity feed spray gun can be cleaned in a gun cleaner, Figure 28-44. The spray gun and cup are separated, the paint passage of the spray gun is positioned over a nozzle, and the gun trigger is blocked open. The cup is placed over another nozzle. After the lid is closed and the gun cleaner is turned on, a pump in the cleaner forces thinner through the paint passages and into the cup. How clean the spray gun becomes is related to how clean the thinner is. Once the cleaning cycle is completed, the gun is removed and wiped off. Waterborne Cleaning Do not use solvents, like lacquer thinner, to clean the waterborne paint from a spray gun. The solvent will change the waterborne paint into a hard, diffi- cult to remove crust inside the spray gun. Empty any basecoat remaining in the spray gun into the aqueous waste barrel. Fill the cup one fourth full of water and trigger the gun into the aqueous waste barrel, then take off the air cap, filter, and cup. See Figure 28-45. Goodheart-Willcox Publisher Figure 28-42. Trigger the spray gun (without air pressure) over the waste thinner barrel while squirting thinner through the spray gun. The thinner is squirted from an aerosol can. Goodheart-Willcox Publisher Figure 28-43. The needle is removed and wiped. Goodheart-Willcox Publisher Figure 28-44. In this gun cleaner, the gravity feed cup and gun are positioned on nozzles so thinner can be pumped through them. Goodheart-Willcox Publisher Figure 28-45.With the trigger pulled, aqueous cleaning fluid is pumped through the spray gun.