Wrought and Specialty Zinc
Everything zinc that is not a die-casting alloy: rolled Zn-Cu-Ti sheet and strip (EN 988) for roofing, cladding and formed architectural parts, the gravity-poured tooling and slush-casting alloys, refined zinc ingot in its commercial purities, and the sacrificial anode alloys. Zn-Cu-Ti holds about 0.1–1 % copper and 0.1–0.2 % titanium, which cut the creep of pure zinc by an order of magnitude and give sheet of about 150–200 MPa tensile that weathers to a self-healing gray patina. Kirksite (essentially Zamak 2 poured into a mold) makes prototype stamping dies and injection molds that last a few thousand shots.
Popular wrought and specialty zinc grades
Compare in the explorer| Grade | Yield, MPa | Tensile, MPa | Density, g/cm³ | Machinability | Weldability | Best for |
|---|---|---|---|---|---|---|
| Zn-Cu-Ti | 120 | 165 | 7.2 | Very good | Fair | Rolled roofing, cladding and pressed-sheet hardware |
| Slush Metal | 130 | 180 | 6.6 | Very good | Poor | Hollow decorative castings and spin-cast prototypes |
| Kirksite | 190 | 227 | 6.7 | Excellent | Poor | Prototype stamping dies and short-run injection molds |
| SHG Zinc | 20 | 30 | 7.14 | Good | Fair | 99.99 % melt stock for Zamak and plating anodes |
| Prime Western Zinc | 20 | 35 | 7.14 | Very good | Poor | Hot-dip galvanizing bath grade |
| Zinc Anode Alloy | 50 | 80 | 7.13 | Very good | Poor | Sacrificial anodes for hulls and seawater structures |
| Zn99.99 | 65 | 145 | 7.14 | Good | Poor | High-purity ingot for alloying and thermal spray |
All 8 wrought and specialty zinc grades
Choose wrought and specialty zinc for
Roofs, façades, gutters and flashings that must last 60–100 years without paint; spun, pressed or deep-drawn architectural and lighting hardware in sheet; hollow decorative castings and spin-cast prototypes; short-run stamping dies and prototype injection molds in Kirksite; sacrificial anodes for hulls, piers and buried steel; and refined zinc for galvanizing, plating and alloying.
Look elsewhere when
The part is a structural or precision casting in volume (Zamak 3 or ZA-8 die castings), it carries load above about 100 °C or is a spring (zinc creeps — brass or aluminum), it must be bent cold below about 10 °C or on a tight radius across the grain (5052 aluminum or copper sheet), the tooling must run more than a few thousand shots (P20 or H13 steel), or a marine anode has to work in fresh water or soil, where magnesium anodes or high-purity zinc grades are used instead.
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Wrought and specialty zinc by application
- Roofing, cladding and flashings
- Zn-Cu-Ti sheet in 0.65–0.8 mm, natural or pre-weathered, standing-seam or panel systems; it self-heals scratches with a zinc carbonate patina and needs no coating in atmospheric service.
- Soft tooling and prototypes
- Kirksite cast to shape and machined for prototype draw dies, stretch blocks and injection-mold cavities that see hundreds to a few thousand parts; Slush Metal or ZA-12 spin-cast in silicone or graphite molds for prototype castings without a die.
- Cathodic protection
- Zinc Anode Alloy (ASTM B418 Type I) for hull, rudder, pier and offshore anodes in seawater — about 780 A·h/kg and a potential of –1.05 V against silver chloride; Type II high-purity grade for brackish water and soils where the aluminum-doped alloy passivates.
- Galvanizing and plating stock
- Prime Western Zinc for hot-dip galvanizing baths, SHG Zinc for electrogalvanizing and plating anodes and as the melt stock every Zamak and ZA ingot is made from.
Working with wrought and specialty zinc
- Forming and fabricating sheet
- Zn-Cu-Ti bends, folds, seams and spins readily at room temperature above about 10 °C — colder than that it turns brittle, so warm the sheet or the shop in winter — with generous radii across the rolling direction and tighter along it. It shrinks and grows about 2.2 mm per metre per 100 °C, twice as much as steel, so long panels need floating clips and expansion joints; it also work-hardens little and stays formable through multiple operations.
- Joining
- Soft-soldered with tin-lead or lead-free tin alloys and a zinc-chloride flux — the traditional roofer’s seam — or mechanically seamed; TIG welding is possible but uncommon because zinc boils at 907 °C, close to its melting point. Kirksite and slush castings are usually not welded; defects are filled by pouring or brazing with zinc-based rod.
- Casting soft tooling
- Kirksite is melted at about 400 °C and poured into sand, plaster or ceramic molds around a pattern, then machined to finish — a stamping die pair in days rather than weeks, at about 100 HB, good for aluminum and mild-steel sheet in the hundreds to low thousands. Slush casting pours the alloy into a two-part mold, waits a few seconds for a skin to freeze, and drains the rest for a hollow part.
- Finishing
- Architectural zinc is left bare to weather from bright to blue-gray in one to five years, or bought pre-weathered; it must not be in contact with copper runoff or uncoated steel, and acidic timber (oak, cedar) or bitumen drips will stain it. Slush and Kirksite castings polish, plate (copper strike first) and paint like Zamak. Pure zinc ingot and anodes are used bare.
Other zinc alloy series
Wrought and Specialty Zinc — frequently asked
What is wrought and specialty zinc?
Everything zinc that is not a die-casting alloy: rolled Zn-Cu-Ti sheet and strip (EN 988) for roofing, cladding and formed architectural parts, the gravity-poured tooling and slush-casting alloys, refined zinc ingot in its commercial purities, and the sacrificial anode alloys. Zn-Cu-Ti holds about 0.1–1 % copper and 0.1–0.2 % titanium, which cut the creep of pure zinc by an order of magnitude and give sheet of about 150–200 MPa tensile that weathers to a self-healing gray patina. Kirksite (essentially Zamak 2 poured into a mold) makes prototype stamping dies and injection molds that last a few thousand shots.
Which grade of wrought and specialty zinc should I use?
Zn-Cu-Ti for any rolled zinc product — standing-seam roofing, façade panels, flashings, gutters, spun and pressed hardware — in 0.65–1.0 mm for architecture and heavier gauge for pressed parts; it is the only zinc sheet with useful creep resistance. Slush Metal (a Zn-Al-Cu alloy of about 380 °C melting point) for hollow lamp bases, figurines and trophy parts poured into an open mold and drained, and for spin-cast prototypes without a steel die. Kirksite for soft tooling: draw dies, stretch-forming blocks, short-run stamping dies and low-volume injection-mold cavities that are cast, machined and later remelted. SHG Zinc (99.99 %) is the melting stock for Zamak and the electroplating anode grade; Prime Western Zinc (about 98.5 %, lead-bearing) is the hot-dip galvanizing bath grade. Zinc Anode Alloy (ASTM B418, MIL-DTL-18001) is the aluminum-cadmium-doped grade for hull, pier and pipeline anodes in seawater; Zn99.99 and Zn99.5 are the high-purity and commercial ingot grades for alloying, thermal-spray wire and chemicals.
Which grade of wrought and specialty zinc is the strongest?
Kirksite has the highest yield strength in the series at 190 MPa; Slush Metal follows at 130 MPa. Values are for each grade's default condition.
Which grade of wrought and specialty zinc is easiest to machine?
Kirksite (machinability excellent, 85/100), then Zinc Anode Alloy (80/100).
Is wrought and specialty zinc heat-treatable?
No. These grades are strengthened by cold work and softened by annealing, not by heat treatment; the conditions are listed on each grade page.
Why alloy roofing zinc with copper and titanium?
Pure rolled zinc creeps and sags under its own weight on a warm roof and tears at seams because it has almost no strength above room temperature. About 0.1–1 % copper raises the tensile strength to 150–200 MPa and 0.1–0.2 % titanium forms fine Zn-Ti intermetallics that cut creep by an order of magnitude and refine the grain so the sheet folds without cracking. The alloy still weathers to the same protective patina as pure zinc, which is why EN 988 Zn-Cu-Ti replaced commercial rolled zinc for every architectural use.
How long does a Kirksite die last?
Typically a few hundred to several thousand hits in aluminum, brass or mild-steel sheet up to about 1.5 mm, at roughly 100 HB — enough for prototype stampings, pre-production runs and one-off drawn parts, and the die is remelted afterwards at about 400 °C. Injection-mold cavities in Kirksite run hundreds to a few thousand shots in unfilled thermoplastics before wear and flash set in. For anything beyond that, or for glass-filled or abrasive resins, a P20 or H13 steel insert is the tooling answer and Kirksite is the bridge to it.