Primers are essential in increasing the adhesion of the plastisol onto metal surfaces. Without primers plastisols normally have very little adhesion to bare metal. Loes manufactures two series of solvent-based primers, PA3011 and the 8400 Series. The 3011 series can be used when the substrate is either heated or cold dipped, and is approved for use with MIL-P-20689D Plastisols. The 8400 series should be used only if the substrate is preheated, and is more economical. Primers are clear and non-settling, and can be colored to distinguish application.