Abstract: A paint spray gun comprises a body having a compressed air supply to atomize paint from a paint source external to the gun. The gun has a needle which is spring urged forwardly and retractable by a trigger to control the opening and closing of a nozzle in a spray head. There are two sealing joints between the needle and the body of the spray gun, and they surround a portion of the needle which is upstream from the paint in the direction that the paint flows along the needle and out the nozzle. A sealing cartridge comprises a cylindrical body enclosing the two sealing joints surrounding the needle, and a prestressed compression spring surrounds the needle and is disposed between the two joints and urges the two joints away from each other against solid surfaces that deflect the joints into sealing contact with the needle. A needle support in the form of a single piece opens at one end in the spray head and at its other end contains the sealing cartridge.