Steel Buyers Basics: Painted Steel

In recent years coil coated painted steel (where a full coil of steel is painted on a continuous coil coating line) has been replacing post-painted steel (where steel parts formed bare are then painted one-by-one).  It seems unlikely at first glance that painted coil coated steel can been formed into finished parts (like roof panels or air-conditioner pans) without damaging the paint coating – after all this coating is only about 1/1000 of an inch thick and is essentially plastic.  Nevertheless, even the most extreme forming process works reliably with coil-coated steel.

Furthermore, paints used to coat steel come with very good warranties (depending on what you buy) many lasting as long as the projected life of the part.  In short, painted steel coil is a great product and the suppliers know it, so how does a buyer, with significant volume, negotiate the best possible deal?