• Solid brass (H65, 8.4–8.5 g/cm³) wins on heft and mirror-proof fields, but cold-struck relief caps at 0.80 mm (0.031").

  • Zinc alloy (Zamak 3, 6.6–6.7 g/cm³) wins on deep 3D sculpture, through-cutouts, and complex edges. Molten zinc injected at 410°C (770°F) fills cavities that a press cannot reach.

  • Same blank, different weight: a 38 mm × 3.0 mm (1.50" × 0.118") brass coin runs 32–38 g. The same coin in zinc alloy runs about 20% lighter.

  • Get the thickness right: 3.0–3.5 mm (0.118–0.138") is the range that feels like a coin instead of a token. Standard MOQ is 300 pieces; sampling takes 3–7 working days.

Hold two 40 mm coins in one palm and the difference needs no explanation. One sits heavy and still, its flat field polished bright enough to catch your reflection. The other carries a raised warship, a wolf's head, or a gear-toothed rim standing proud of the surface. Both are well-made coins. They are simply made for different artwork, and picking the metal before reading the artwork is how budgets get wasted.

What your hand notices first: weight and mirror

Brass is dense. At 8.4–8.5 g/cm³ against zinc alloy's 6.6–6.7 g/cm³, a brass coin of the same size carries roughly a quarter more weight, and your hand registers it immediately. For military challenge coins, official crests, and anniversary editions, that heft is part of the message: the coin is meant to feel substantial when it changes hands.

The second thing brass does better is the flat field. Brass coins are struck cold under hundreds of tons of hydraulic pressure. The metal is already solid, so the grain stays dense and free of pores, and a cloth-wheel polish brings the field up to a true mirror proof. Zinc alloy, by contrast, starts as a liquid. As it cools in the mold, the surface keeps faint flow lines that no amount of polishing fully removes. A zinc coin can be bright. It cannot hold a mirror the way brass does.

So when the artwork is flat and heraldic — a clean crest, a perimeter motto, fine lettering — and the brief calls for weight and a mirror field, brass is the right answer. Our commemorative coins are built on exactly this logic: restrained relief, dense metal, and a polished field that does the talking.

What your artwork demands: relief depth and cutouts

The trade-off appears the moment the artwork leaves the flat plane. Cold striking has a hard physical ceiling: relief deeper than 0.80 mm (0.031") cannot be pressed into brass without tearing the metal or cracking the die. If your design carries a high-relief battleship, a rearing animal, a skyline in layered depth, or a through-cutout at the center, brass will fight you — and the tooling pays for it.

Zinc alloy has no such ceiling. Injected molten at 410°C (770°F), it flows into every corner of the die cavity and freezes there, which is why deep, asymmetrical 3D sculpture and pierced centers belong to zinc. Gear-toothed rims, interlocking shapes, mascot heads that stand clear of the field — all of these are routine for die casting and impossible for a cold press. This is the territory our custom 3D challenge coins are made for.

There is one honest caveat. Die casting brings thermal shrinkage: where wall thickness changes abruptly, thicker sections cool slower and can leave faint sink marks on the surface. Our tooling engineers handle this by coring out thick sections from the back and holding a 1.5°–3.0° draft taper on vertical walls. It is a solvable problem, but it is why zinc tooling deserves an engineering review before cutting steel — send the vector file first and the feasibility answer comes back with the proof.

What the budget says: tooling, quantities, and reorders

Brass tooling costs more. The die steel has to survive hundreds of tons of cold pressure, so a small brass run carries a heavy mold cost per coin. At 50 pieces, brass is almost never the economical choice; the mold amortization alone can double the unit price. Zinc tooling is kinder to small and mid-size runs, which is one reason gaming tokens and event coins usually go the zinc route.

Our standard MOQ is 300 pieces, which is where mold cost spreads thin enough for either metal to make sense. Sampling runs 3–7 working days, bulk production 12–18 working days, and a mold stays good for 50,000–100,000 strikes — reorders within that life carry no new mold fee. If you expect repeat orders across years, that last number matters more than the first quote.

A simple decision rule

Comparison table (Brass H65 vs Zinc alloy Zamak 3):

  • Density: 8.4–8.5 g/cm³ — heavy in the palm / 6.6–6.7 g/cm³ — about 20% lighter

  • Forming: Cold-struck, 300–1,000 tons / Hot-chamber die-cast at 410°C (770°F)

  • Relief: Up to 0.80 mm (0.031") / Deep 3D sculpture, no cold-press ceiling

  • Field finish: Mirror proof / Bright polish, faint flow lines

  • Cutouts / odd edges: No / Yes — pierced centers, gear rims

  • Best for: Crests, mottoes, anniversary editions / 3D mascots, vehicles, gaming tokens

  • Watch out for: Mold cost on small runs / Sink marks if walls change abruptly

💡 Factory rule of thumb: if the artwork would still read clearly as a wax seal — flat, crisp, symmetrical — choose brass. If it needs height, holes, or an outline that is not round, choose zinc alloy. When in doubt, the deciding question is never which metal costs more. It is which forming process your artwork can survive.
📋 Copy-paste spec for your custom challenge coin RFQ: 40 mm (1.57") diameter × 3.5 mm (0.138") thick · Zamak 3 zinc alloy, hot-chamber die-cast / H65 brass, cold-struck · relief per artwork (note if any element exceeds 0.80 mm) · antique silver / bright gold / dual-tone plating · 300 pcs MOQ · 3–7 working days sampling.

Frequently Asked Questions

Q: Can a brass coin carry two-tone plating?

A: Yes, and it is one of the strongest looks brass offers. A mirror-polished field in bright gold plating against an antiqued relief in nickel or bronze gives a high-contrast finish that reads as premium without adding a second metal.

Q: Why can't zinc alloy match brass for a mirror finish?

A: The difference is in how the surface forms. Brass is pressed solid under high tonnage, so the grain is dense and pore-free before polishing. Zinc alloy solidifies from a liquid, and the cooling metal leaves microscopic flow lines in the surface. Polishing improves it, but the reflection never reaches the clarity of a cold-struck brass field.

Q: Will a zinc alloy coin feel light and cheap?

A: Not if the thickness is right. At 3.0–3.5 mm (0.118–0.138"), a 40 mm zinc alloy coin still has real presence in the hand — about 20% lighter than the same coin in brass, which most people read as comfortable rather than cheap. Thin coins feel cheap. Correct thickness does not.

Choosing a coin metal is a forming decision before it is a budget decision. If your artwork is already drawn, send it over — our tooling engineers will check the relief depths and wall transitions against the process limits and tell you which metal fits before any steel is cut. You can reach us through the contact page, and if you want the design side of the story first, our notes on challenge coin design cover how a single story becomes a coin people keep.