Zinc Plating, often referred to as Galvanization (in its hot-dip form) or Electro-zinc, is an electrochemical process where a thin layer of zinc is deposited onto a steel or iron part. Because zinc is more chemically active than steel, it acts as an “anode.” When exposed to moisture, the zinc reacts first, forming a white powder (zinc oxide) rather than allowing the steel to form red rust (iron oxide).

Best Industries:

Performance Types:

Best Materials:

Cost-effective zinc plating services for steel fasteners, brackets, and automotive parts. Get superior sacrificial corrosion protection with a high-quality finish.

ASTM B633 compliant zinc electroplating in clear (blue), yellow, and black chromate finishes. Enhance the lifespan of your components with our ISO-certified zinc finishing process.

Key Advantages: Cost-Effectiveness and Protection

Zinc is the “budget-friendly” alternative to Cadmium or Stainless Steel for high-volume manufacturing.

Sacrificial Protection: Even if the coating is scratched or dinged, the surrounding zinc continues to protect the exposed steel through a galvanic reaction.
Excellent Paint Base: Zinc-plated surfaces provide a much better “tooth” for paint and powder coatings to stick to than raw steel.
Aesthetic Variety: Depending on the post-treatment, zinc can look like blue-chrome, yellow-gold, or even matte black.
Low Cost: Zinc is an abundant metal and the plating process is highly automated, making it the most economical choice for bulk hardware.

The Role of Supplemental Coatings

Raw zinc is very reactive and will develop “white rust” quickly. To prevent this, zinc plating is almost always followed by a Chromate Conversion Coating:

Clear/Blue (Trivalent): Provides a silvery, modern look. It is environmentally friendly (RoHS compliant) and common in the automotive industry.
Yellow/Gold (Hexavalent): Traditionally offered better corrosion resistance, though it is being phased out in many regions due to environmental regulations.
Black Zinc: Used for aesthetics and light-reflection reduction; it typically offers slightly less corrosion resistance than yellow chromate.

Specifications

Specification	Comments
ASTM B 633
Type I	As plated, no chromate
Type II	With supplementary chromate treatment
Type III	With supplementary colorless chromate treatment
Type IV	With phosphate conversion treatment. Used to provide a paint base.
SC 4 (very severe)	.0010″
SC 3 (severe)	.00050″
SC 2 (moderate)	.00030″
SC 1 (mild)	.00020″
Corrosion resistance requirements	Type II 96 hours Type III 12 hours

Industry Applications

Zinc is the standard finish for the construction, automotive, and appliance industries:

Fasteners: Bolts, nuts, and screws used in indoor and mild outdoor environments are almost always zinc-plated.
Automotive Brackets: Under-the-hood components that aren’t exposed to extreme heat but need protection from road salt and humidity.
Construction Hardware: Hinges, brackets, and plates used in home building.
Retail Displays: Wire shelving and racks often use “bright zinc” for a clean, chrome-like appearance at a fraction of the cost.

Finish Comparison

	Zinc Plating	Zinc-Nickel Plating	Cadmium Plating
Coating Thickness	Thin (5–20 µm)	Thin (8–15 µm)	Thin (5–20 µm)
Corrosion Defense	Moderate	Very High (1,000+ hrs)	Extreme (Marine)
Precision	High (Good for threads)	High (Excellent for threads)	N/A (Is SolderHigh
Appearance	Bright / Decorative	Semi-bright / Grey / Black	Silvery / Yellow
Environment	Indoor / Mild Outdoor	Automotive / High-Salt	Marine / Aerospace

Zinc Plating
Coating Thickness	Thin (5–20 µm)
Corrosion Defense	Moderate
Precision	High (Good for threads)
Appearance	Bright / Decorative
Environment	Indoor / Mild Outdoor

Zinc-Nickel Plating
Coating Thickness	Thin (8–15 µm)
Corrosion Defense	Very High (1,000+ hrs)
Precision	High (Excellent for threads)
Appearance	Semi-bright / Grey / Black
Environment	Automotive / High-Salt

Cadmium Plating
Coating Thickness	Thin (5–20 µm)
Corrosion Defense	Extreme (Marine)
Precision	N/A (Is SolderHigh
Appearance	Silvery / Yellow
Environment	Indoor / Mild Outdoor

Why Choose One Over the Other?

Zinc Plating: The “Industrial” Choice

As noted with automotive brackets and hardware, Zinc is the global standard for general rust protection. It is extremely cost-effective and provides excellent “sacrificial” protection in standard atmospheric conditions. However, in high-moisture or stagnant environments, zinc can develop a bulky, white powdery corrosion product known as “white rust.” To prevent this, it is almost always finished with a chromate conversion coating (Clear, Yellow, or Black).

Best for: Automotive chassis parts, construction fasteners, and indoor/outdoor brackets that do not face extreme salt exposure.

Zinc-Nickel: The “Modern” Choice

Since Cadmium is a toxic carcinogen, many industries are switching to Zinc-Nickel (Zn-Ni) as a safer alternative. Zinc-Nickel bridges the gap: it offers much higher corrosion resistance than standard zinc (often exceeding 1,000 hours of salt spray testing) and provides better thermal stability. It is rapidly becoming the new “Gold Standard” for automotive and aerospace components that need cadmium-level protection without the environmental hazard.

Best for: Engine compartment parts (high heat), electric vehicle components, and modern aerospace fasteners.

Cadmium Plating: The “Marine & Aerospace” Choice

Cadmium is the “ultimate” sacrificial coating for the most punishing environments. Unlike zinc, cadmium is exceptionally resistant to salt-water corrosion and does not produce the bulky white corrosion products that can jam moving parts. It is also naturally “lubricious” (slippery), which prevents galling—the tendency of threaded parts to lock up or seize under high torque. Because it is highly toxic and regulated (RoHS), it is strictly reserved for high-stakes industries.

Best for: Aircraft landing gear, naval ship hardware, and military parachute buckles where failure or “seizing” is catastrophic.

A Note on Hydrogen Embrittlement

Just like with Nickel and Cadmium, high-strength steel parts (Grade 8 bolts or parts with hardness > HRC 31) are at risk of Hydrogen Embrittlement during the zinc plating process. To prevent catastrophic failure, these parts must be baked in an oven shortly after plating to allow the hydrogen to escape before it becomes trapped in the metal’s grain structure.