What is Zamak? It is the name of a family of zinc alloys used to cast a large share of fashion's metal buttons, buckles, rings, zip pullers and decorative hardware. The name comes from the German words for its ingredients: Zink (zinc), Aluminium, Magnesium and Kupfer (copper). This article explains exactly what Zamak contains, which grades are used, why it dominates garment hardware, where its weaknesses lie and when it makes sense to choose brass instead.
Glossary: the key terms
- Zamak / ZAMAK / Zamac – the trade and everyday name for zinc-aluminium die-casting alloys.
- ZnAl4 – the European designation by composition: zinc with about 4% aluminium.
- EN 1774 / EN 12844 – the European standards for zinc alloys in ingot form and as castings respectively.
- Die casting – molten alloy is injected under high pressure into a steel mould.
- Electroplating – a thin metal layer applied by electrolysis that provides colour and protection.
- White rust – the whitish corrosion product of zinc when the plating is damaged.
Plastic bra sliders and rings
Metal ring and slider R&R – 8 mm bronze set
Metal rings E-2315 Nickel – Buckle type, Oval model with beads – 2.5 cmComposition by grade
| Grade | European designation | Aluminium | Copper | Magnesium | Character |
|---|---|---|---|---|---|
| Zamak 3 | ZP3 / ZnAl4 | about 4% | trace | about 0.04% | the most widely used; good dimensional stability |
| Zamak 5 | ZP5 / ZnAl4Cu1 | about 4% | about 1% | about 0.05% | harder and stronger thanks to copper; common for buttons |
| Zamak 2 | ZP2 / ZnAl4Cu3 | about 4% | about 3% | about 0.04% | strongest and hardest, less common in trims |
| Zamak 7 | – | about 4% | trace | very low | flows better, for thin-walled parts |
The rest – roughly 95% – is high-purity zinc. The standards limit impurities such as lead, cadmium and tin because they cause intergranular corrosion. In fashion hardware, Zamak 3 and Zamak 5 are the grades you will meet most often.
Why Zamak dominates garment hardware
1. Low casting temperature
Zamak melts at around 380–390 °C and is cast at roughly 385–450 °C. That is far lower than brass and allows hot-chamber die casting – fast, and kind to steel moulds, so one mould can produce a very large number of castings.
2. Excellent detail
The molten alloy fills even the finest relief in the mould: crests, logos, textures, openwork buckles. Shapes that would have to be stamped and assembled from brass sheet come out of Zamak in a single shot.
3. Easy to finish
Castings are easy to trim, polish and tumble, and the surface takes electroplating very well. The same casting can be finished in nickel, gold, gunmetal, antique brass or black.
4. Cost and weight
Zamak is cheaper than brass both as raw material and in processing complex shapes. Its density is about 6.6–6.7 g/cm³ – lighter than brass (about 8.4–8.7 g/cm³) but heavy enough to feel like quality.
How a Zamak button or buckle is made
- Mould – a steel die cut to the design, often with several cavities.
- Casting – the alloy is injected and solidifies in seconds.
- Cleaning – runners are cut off and parts are tumbled smooth.
- Polishing – for bright finishes.
- Electroplating – usually a copper underlayer, then the final finish; nickel-free versions use nickel-free plating systems.
- Lacquer – optional, for extra protection and a matt or gloss look.
The weaknesses you should know
- It needs plating. Bare zinc is greyish and dulls over time. Appearance and protection come from the plating.
- Corrosion under damaged plating. If plating is scratched or incomplete, zinc reacts with moisture and sweat and forms white rust. Sweat, sea water and chlorine speed this up.
- It dislikes bending. Zamak is more brittle than brass. Parts that deform during setting – snap prongs, rivets that are flattened – are usually brass or steel, with Zamak used for the decorative cap.
- Heat. Under sustained high temperature and load the alloy can slowly creep – irrelevant for clothing in use, but worth knowing for some industrial processes.
Zamak and safety
The alloy itself contains no nickel, but plating often does. Under REACH, metal parts in prolonged contact with skin must not release more than 0.5 µg/cm² of nickel per week. So for jeans buttons, belt buckles and anything against the skin, ask for a nickel-free finish. REACH also restricts lead in articles – a standard-grade alloy meets these limits with a wide margin.
Caring for Zamak hardware
Well-plated Zamak lasts for years in normal wear. Wash garments fastened and inside out so metal parts don't knock against the drum, dry them promptly – especially after sea water or a pool – and avoid bleach and harsh detergents that attack the plating.
When to choose brass over Zamak
- When the part is bent or crimped during setting – prongs, rivets, eyelets.
- For swimwear, marine and sports gear exposed to constant moisture and chlorine.
- When you want more weight and an "old gold" that ages beautifully without plating.
- For luxury jackets and coats where the button must last for decades.
A detailed comparison of the two metals is in our article on zinc alloy versus brass – see our button articles.
Tip: you can't tell Zamak from brass by colour, because the plating looks the same. If it matters, ask the supplier about the base material and request a specification.
FAQ
Is Zamak a "cheap" material?
No. It is an industry standard used by premium brands too. Quality depends on the alloy, the mould and the plating, not just the metal.
Can Zamak rust?
Zinc doesn't rust like iron, but it corrodes with a white bloom if the plating is damaged.
Is it magnetic?
No. If a button sticks to a magnet, it contains steel or iron.
At Bul-tex you will find metal buckles, snap buttons and buttons in a range of finishes. For questions about the material of a specific item or custom hardware, get in touch.
