How should rust and corrosion be prepared?
If there is a rust stain on wood or stucco, it should either be drilled out at least 1/4″ – 1/2,” primed, filled and then coated over. Simply treating the stain or rusted fastener with osforic acid and spot priming is not adequate and the rust stain will come back in a short time. On iron brackets, electrical conduit, hinges, etc., if the rust cannot be removed by either cutting it out or sandblasting, the rust will come back. There are some coatings that offer years of protection against bleed-through, but if the rust is not properly removed, it will come back eventually.
