But untreated bronze as used by Panerai PAM382 will acquire a patina, which is actually oxidation, over time. Once the surface layer of bronze has oxidised, it forms a protective layer over the rest of the metal.

The changes to the surface of the bronze alloy are front loaded, most of the patina occurs early in use because of the oxidation layer which gradually forms. That contrasts with conventional watch metals like steel or gold, which constantly suffer wear and tear with use.

The prototype Bronzo at SIHH

The prototype shown during SIHH was largely new and thus had only minimal patina; it still retained the copper tone of the bronze alloy.

Incidentally the Panerai bronze alloy is significantly more reddish than the bronze used Anonimo or Gerald Genta, which I assume means it has a higher proportion of copper.

Recently I had the opportunity to examine a PAM382 that had been handled over a longer period, resulting in significantly more oxidation. This watch is a prototype that has been shown to members of the press around the world. Though the patinated Submersible Bronzo looks somewhat like a grimy watch, it is actually attractive. The surface is variegated, with spots and patches of different shades. It sounds almost like the description of skin ailment but as the cliche goes, the case has character. And the resulting patina on the case matches the green dial perfectly.

Panerai collectors rank up there with vintage Rolex collectors as connoisseurs of patina, witness the reverence for vintage Panerai, or the attempts to artificially age leather straps by dunking them in olive oil for example, and so this watch will be a hit.

That, however, brings to mind an interesting issue. One of the key attractions of Panerai watches is the potential for appreciation and liquidity; Panerai watches are some of the most heavily traded.

But since the Bronzo acquires a patina over time, how will the watches be received on the secondary market? I can imagine bizarre attempts to keep it patina free. – SJX Update 17 March 2012: Photos of a month old Panerai Bronzo which has already developed a noticeable patina.

A closer look at the Bronzo with character

The Negretti Burton book (below right) is an excellent reference on Panerai; the other is a book on a yachting race that Panerai sponsors and authored by its CEO Angelo Bonati.