Is this is? Its in the Sherwin-Williams industrial and marine coatings side: COROTHANE® I MASTIC Corothane I Mastic is a single component, moisture curing urethane with micaceous iron oxide, designed as a primer or intermediate coat for previously painted steel surfaces, including lead overcoating. It is high solids and VOC compliant. Product is designed to be topcoated. or: Epoxy Mastic Aluminum II was applied next. This high-build mastic is ideal for added corrosion resistance and provides additional film build. While it can be applied at temperatures down to 35°F, the Thruway Authority approved its use on the bridge in condtions where the air and surface temperatures are 50°F or above. Its used on bridges, tanks, and other commercial/industrial apps, likely better stuff then POR 15! see: http://www2.sherwin-williams.com/im/bridgehighway/corothaneimastic.asp?nav=Products - Bill
If you sandblast it properly (I'm talking industrial style here, not some hand held thing with a bag of sand), the entire frame will be bare metal inside and out...easy to check for issues, easy to touch up rough areas (bad welds etc). Also smooths over rough spots due to rust etc but need ot be careful you don't erase codes or numbers. We are lucky here to have a rental place like that, cost 150.00 for time at blaster, another 500.00 for powdercoating plus other parts as well. That was a few years ago.
