We were tasked we specifying and implementing a long term solution to protect the ferric metal structure on these cupolas.
Being on the roof, they receive full exposure to sunlight and all environmental conditions. Their severely degraded condition was a result of being out-of-sight, out-of-mind. Not having renewed their protective coatings for many years left the raw metal exposed to the elements. Fortunately, the rust was not cancerous.
We pulled from our many years of experience and training in coating existing metal surfaces. Working from the SSPC standards, we pressure washed, sanded, and ground the substrate by hand and with power tools and then solvent wiped them clean prior to applying coatings.
We installed two coats of two-component, high-performance, 85% solids epoxy primer and finished coated with a two-component, polyester-acrylic aliphatic polyurethane.
The results were phenomenal. The expectation is that this system will provide protection for 10+ years. A typical architectural coating system of clean, spot prime and finish coat in an alkyd enamel provides a 2-4 year solution. Assuming reasonably well-prepared surfaces.