I believe that a correctly passivated stainless steel must be exposed to air to enhance and continually reinforce the passivated microscopic layer present on the surface. It is this thin layer that permits, even regenerates, the active chemicals that provide the resistance. Sealing this passivated surface interrupts the oxygen flow and begins the actual degradation of the surface. Subsequent layers of additional coverings would only speed up the degradation of this effect. It would be better to acid etch in desired colors prior to construction. G.D.
I don’t know, G.D. I don’t know how I can explain this to the brothers at the next lodge meeting of the Ancient and Venerable Order of Paint Chemists. I usually scratch my head anyway when people want to paint stainless steel, but this is the first time I heard this reason. I hope this is neither an urban legend nor an old wives tale. As an organic chemist, I am out of my element, but if you noticed, never at a loss for words. I guess I’ll have to defer to the metallurgists. However I will ask for a second opinion. Do any of my loyal Painting Clinic readers have an opinion on this subject?