Zinc

Zinc anodizing forms a thin conversion coating on zinc parts for corrosion protection, better paint adhesion, and controlled matte or decorative finishes.

Overview

Zinc anodizing is a chemical conversion process that grows a controlled oxide/hydroxide layer on zinc or zinc-alloy parts, especially die castings. The porous coating improves corrosion resistance, serves as an excellent base for paint or powder coat, and can provide a uniform matte or slightly colored decorative finish. Coating thickness is typically thin, so dimensional change is minimal on most features.

Use zinc anodizing when you already have a zinc or Zamak part and need low- to medium-cost corrosion protection without the buildup of thick platings or paints. It works well for housings, brackets, and small hardware where appearance and paint adhesion matter more than wear resistance. Tradeoffs: the coating is softer and less abrasion-resistant than hard anodized aluminum, color options are more limited, and process control is critical for uniform appearance across complex die-cast geometries. Complex pockets, sharp edges, and heavy casting defects can lead to non-uniform coating, so good upstream casting and clear specs are important.

Common Materials

  • Zinc die casting
  • Zamak 3
  • Zamak 5
  • Zinc sheet
  • Zinc bar

Tolerances

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Applications

  • Die-cast electronic housings
  • Automotive small brackets and clips
  • Architectural zinc trim components
  • Consumer product zinc handles and knobs
  • Zinc hardware requiring paint or powder coating

When to Choose Zinc

Choose zinc anodizing when your base material is zinc or Zamak and you need improved corrosion resistance with minimal dimensional change. It fits well for medium to high production volumes of small to medium parts that need consistent appearance and a good paint or powder-coat base. Use it where cosmetic uniformity and adhesion are more important than extreme wear resistance.

vs Aluminum

Choose zinc anodizing over aluminum anodizing when the part is already designed and sourced in zinc or Zamak, especially complex die castings. It avoids redesigning the part for aluminum and lets you upgrade corrosion resistance and paint adhesion on existing zinc hardware and housings.

vs Titanium

Pick zinc anodizing instead of titanium anodizing when cost and manufacturability push you toward zinc die casting for volume production. It suits decorative or lightly loaded parts where corrosion protection and finish matter, but you don’t need titanium’s strength, temperature resistance, or medical-grade performance.

vs Magnesium

Use zinc anodizing instead of magnesium anodizing when you want the casting and finishing to be more forgiving and less reactive. Zinc die castings with zinc anodizing usually offer better corrosion robustness in everyday environments and simpler handling than magnesium components, at the expense of higher density.

vs Niobium

Select zinc anodizing over niobium anodizing for cost-sensitive, high-volume consumer or industrial parts where you’re already tooling zinc die castings. Niobium is typically reserved for niche high-tech or medical uses, while zinc plus anodizing gives practical corrosion resistance and aesthetic control at much lower part cost.

vs Tantalum

Choose zinc anodizing rather than tantalum anodizing when you do not need extreme chemical resistance or specialized electronic properties. Zinc parts with anodized finishes are far cheaper and better suited to general industrial, automotive, and consumer applications than tantalum-based designs.

Design Considerations

  • Call out coating type, target thickness range, and acceptance criteria for color and gloss so finishers can process and inspect consistently
  • Identify and dimension critical fits and threads that must be masked to prevent coating buildup or adhesion issues
  • Avoid very deep blind holes, sharp internal corners, and tight crevices where solution flow and coating uniformity will be poor
  • Provide small drain/vent holes on pockets and enclosed features so parts can be processed and rinsed without trapping chemistry
  • Specify allowable cosmetic defects and which faces are cosmetic vs non-cosmetic to control cost and rework
  • Coordinate with your caster to minimize porosity and flash, since surface defects telegraph through the anodized zinc finish and increase scrap