Galvanically. Zinc is more electrochemically active than iron, so when the two are connected in the presence of moisture the zinc corrodes preferentially and the steel does not. This is why a galvanised coating keeps protecting steel at a scratch or cut edge, where a paint film would simply expose bare metal and allow rust to start.

A layer of basic zinc carbonate that forms naturally as the surface weathers, changing bright rolled zinc to a stable matte blue-grey over months to years. It is adherent and self-healing at scratches, and it substantially slows further corrosion, which is what allows zinc roofing and cladding to be installed bare with no coating maintenance.

Its melting point is low enough that ordinary ambient temperature is a substantial fraction of it in absolute terms, so the diffusion processes that cause creep in other metals only when hot are already active in zinc when cold. Sustained static loads therefore produce slow permanent deformation, and zinc should not carry continuous structural load.

Acids and strong alkalis. In practice the common offenders are run-off from fresh cement, mortar and concrete, which is strongly alkaline, and water carrying tannins from unseasoned oak or western red cedar. Copper run-off is also damaging because it plates out and sets up a galvanic cell. Detailing has to keep all of these off the sheet.

Architectural sheet is typically zinc-copper-titanium: small copper and titanium additions raise strength and, importantly, sharply improve creep resistance over pure zinc, which is what makes it viable as a roofing material. Die casting uses a separate family, the ZAMAK zinc-aluminium alloys.

Soldering is the traditional joining method for gutters, flashings and rainwater goods, using a zinc chloride flux, and it is well established in the roofing trades. Fusion welding is possible but rarely used on site. Most architectural work relies on folded and welted seams, with soldering reserved for joints that must be watertight.

Low melting point, excellent fluidity and high dimensional accuracy. It fills thin sections and fine detail readily, holds tight tolerances, needs little finishing, and because it is cast at low temperature the dies last far longer than aluminium dies. That combination makes it economical for small, complex, high-volume parts such as locks and connector housings.