Zinc Aging and Weathering
Zinc is one of the few materials designed for long-term projects. Whereas an aluminum facade is only specified to last a few decades, zinc is a noble metal that can last upwards of 120 years.
In environments with prolonged direct moisture, the outward facing of the zinc may be susceptible to white-gray areas and streaks, with our without a patinated surface. Typical conditions will darken the patina over time. However, in moisture-heavy regions, the material will lighten over time. The combined result is that the patina will grow over time. Zinc is a sophisticated material that ages with integrity not unlike the elegance of a copper patina.
For best performance, the back face of the zinc material should not be exposed to moisture. If exposed to moisture attack from the reverse side, it may result in perforation/disintegration of the surface over time. This is why the back facing of zinc is sometimes covered with plastisol or a similar coating.