Marks on unpainted metals will bleed through primers and top coat before a sealant is applied. Remember to keep the tip saturated for proper bleed-thru capability. IM-13, IM-14, & IM-15 are to be used with oil-based primers. IM-63 is to be used with water-based primers. To seal your marks and stop bleed through on IM-13, 14, and 15, you must apply a water-based or alcohol based sealant. To stop bleed through on IM-63, you must use an oil-based sealant.