Raven 581 is a 100% solids, no VOC, modified polyurethane designed for use as a manhole “chimney seal”. Raven 581 can be used in high humidity conditions with minimal bubbling and loss of adhesion. The 581 adheres well to properly prepared substrates such as steel, aluminum, wood and concrete. Some substrates exhibit much better long term performance if a primer is used prior to application. For example, a steel substrate coated with Raven 581 performs much better in corrosion conditions testing if the steel is treated prior to coating with the proper preparation method (i.e. shot blasting), proper primer (i.e. that includes rust resistant additives), and then top coated with Raven 581. Contact Raven for primer recommendations for various substrates.