Zn99.995 SHG Zinc Wire: ASTM B833 Thermal Spray Guide

If you are sourcing Zn99.995 SHG zinc wire for thermal spray or electric arc spray applications, understanding the difference between 99.9% and 99.995% purity — and how ASTM B833-20 governs wire specification — is critical to coating performance, project lifespan, and procurement compliance.This guide covers everything a procurement manager, corrosion engineer, or thermal spray contractor needs to know about SHG (Special High Grade) zinc wire with 99.995% purity, with a focus on the popular 3.2 mm (1/8″) diameter used in electric arc spray systems. We include real-world case studies, market data, chemical specs, and a purity comparison to help you make an informed sourcing decision.

✅ASTM B833-20 Compliant
✅Zn99.995 SHG per ASTM B6
✅Ø3.2 mm / Ø1.6 mm
✅ISO 14919 / DIN 14919
✅SGS MTC per Batch

1. What Is Zn99.995 SHG Zinc Wire?

Zn99.995 denotes a zinc purity of 99.995% minimum — the highest commercially available grade of pure zinc, also known as Special High Grade (SHG) as defined by ASTM B6 (Standard Specification for Zinc). The total impurity content is limited to a maximum of 0.005% (50 parts per million).

When drawn into wire for thermal spray and metallizing applications, SHG zinc wire must additionally conform to ASTM B833-20 (Standard Specification for Zinc and Zinc Alloy Wire for Thermal Spraying for the Corrosion Protection of Steel) and ISO 14919 (Wires, rods and cords for thermal spraying).

Key fact: Zn99.995 is the only purity grade that guarantees full compliance with ASTM B833-20, ISO 14919, and DIN 14919:2001 for critical infrastructure corrosion protection.

Common diameters for thermal spray wire include Ø1.6 mm (1/16″) and Ø3.2 mm (1/8″), with 3.2 mm being the preferred diameter for high-deposition electric arc spraying on bridge, marine, and industrial steel structures.

2. Chemical Composition – Zn99.995 vs. Lower Purity Grades

The table below compares the chemical composition limits for Zn99.995 SHG zinc wire against industry requirements. The difference in impurity control directly affects coating quality, nozzle life, and long-term corrosion performance.

Element	Zn99.995 SHG (ASTM B6)	Zn99.99 (Standard Grade)	Zn99.9 (Commercial Grade)
Zinc (Zn) min	99.995%	99.99%	99.9%
Lead (Pb) max	0.003%	0.005%	0.02%
Iron (Fe) max	0.002%	0.005%	0.02%
Cadmium (Cd) max	0.002%	0.003%	0.01%
Copper (Cu) max	0.001%	0.002%	0.01%
Tin (Sn) max	0.001%	0.002%	0.01%
Total Impurities max	0.005% (50 ppm)	0.01% (100 ppm)	0.1% (1,000 ppm)
ASTM B833-20 Compliant	✅ Yes	✅ Yes*	❌ No
ISO 14919 Compliant	✅ Yes	✅ Yes*	❌ No

* Zn99.99 may qualify if individual impurity limits still meet ASTM B833 Table 1 requirements. Always verify with Mill Test Certificate.

3. ASTM B833-20 – What the Standard Requires

ASTM B833-20 sets the following key requirements for zinc thermal spray wire:

3.1 Chemical Composition

The wire must meet the chemical limits shown in the table above. For pure zinc wire, the standard references ASTM B6 Special High Grade as the base specification.

3.2 Dimensional Tolerances

Nominal Diameter	Tolerance	Out-of-Roundness
Ø1.6 mm (0.063″)	± 0.05 mm	≤ 0.05 mm
Ø3.2 mm (0.125″)	± 0.07 mm	≤ 0.07 mm
Ø4.0 mm (0.158″)	± 0.08 mm	≤ 0.08 mm

3.3 Mechanical Properties

Tensile Strength: Typically 100–180 MPa, depending on diameter and temper
Elongation: ≥ 15% for optimal feedability through arc spray guns
Surface Condition: Clean, smooth, free of oil, grease, and oxide inclusions

3.4 Testing & Certification

Mill Test Certificate (MTC) per EN 10204 Type 3.1 covering full chemical analysis and mechanical properties
Tensile and elongation testing per ASTM E8/E8M
Chemical analysis per ASTM E536
Third-party inspection (SGS, Intertek, Bureau Veritas) available on request

4. Why 3.2 mm (1/8″) Is the Standard for Arc Spray

The 3.2 mm diameter is widely regarded as the workhorse size for electric arc spray systems because:

Wire feed stability: 3.2 mm wire provides sufficient stiffness for reliable push-feed through 10–25 meter hoses without buckling
Deposition rate: A single arc spray gun with 3.2 mm SHG zinc wire achieves a typical deposition rate of 12–25 kg/hour depending on amperage and air pressure
Atomization efficiency: The 3.2 mm cross-section produces a consistent droplet size distribution when atomized at 4–6 bar air pressure, giving a dense, low-porosity coating
Compatibility: 3.2 mm wire feeds through standard contact tips for Thermion, Metco, Praxair, Oerlikon, and Castolin Eutectic arc spray guns

5. Arc Spray Parameters for 3.2 mm SHG Zinc Wire

Parameter	Recommended Range
Wire Diameter	3.2 mm (1/8″)
Voltage	28–35 V
Current	150–350 A (higher current = higher deposition rate)
Spray Distance	150–250 mm
Atomizing Air Pressure	4–6 bar (60–90 psi)
Wire Feed Speed	1.5–3.5 m/min
Deposition Efficiency	60–75%
Coating Thickness per Pass	75–200 µm
Bond Strength (per ASTM C633)	> 8 MPa (steel substrate, Sa 3 blast)
Coating Density	> 90% theoretical density

Note: For maximum bond strength and density, the steel substrate must be abrasive-blasted to Sa 3 (white metal) per ISO 8501-1, with a surface roughness profile of 75–125 µm (Rz). A sealer coat applied within 4–6 hours of spraying extends service life by 2–3x in aggressive environments.

6. Why Purity Matters: Zn99.995 vs. Lower Grades

Using lower-purity zinc wire (99.9% or ungraded material) introduces several risks:

Non-compliant coatings: Projects specifying ASTM B833 or ISO 14919 may reject coatings applied with non-certified wire
Increased impurity content — particularly lead and iron — can create galvanic micro-cells within the coating, accelerating localized corrosion
Nozzle clogging from oxide inclusions and tramp elements, increasing downtime and reducing deposition efficiency
Inconsistent coating quality: Variable feed and atomization behavior due to hardness and surface quality variations

“For bridge, marine and long-life anti-corrosion work, we recommend 99.995% zinc wire, with Fe, Pb, Cd, Cu and Sn limits clearly checked on the Mill Test Certificate. The additional cost of SHG grade is minimal compared to the cost of premature coating failure on a $50M+ bridge structure.”
— Industry sourcing recommendation, published on China Ferroalloy Network

7. Real-World Application: Zinc Metallizing on Bridges & Infrastructure

Thermal spray zinc has a decades-long track record in critical infrastructure. Key studies and projects include:

7.1 U.S. FHWA Study (Federal Highway Administration)

The FHWA concluded after long-term exposure testing: “Metalized systems consistently provided the best corrosion protection performance. All metalized coatings tested showed no corrosion.” Thermal spray zinc was tested alongside multi-coat paint systems and outperformed all alternatives in coastal and industrial environments.

7.2 Rainbow Bridge, Niagara Falls (USA-Canada)

The Rainbow Bridge — a major international crossing — was metallized with zinc-based thermal spray coating. The project specified the 85/15 Zn-Al alloy for its dual-phase corrosion protection, and the coating system has delivered maintenance-free service for over 20 years in a challenging freeze-thaw and deicing salt environment.

7.3 Norwegian Road Bridges (MDPI Study, 2019)

A peer-reviewed study published in Coatings (MDPI, 2019) examined thermal spray zinc duplex coatings on Norwegian road bridges. The study found that thermal spray zinc with a sealer coat provided 25+ years of corrosion protection in Nordic conditions, with minimal maintenance intervals compared to conventional paint systems.

7.4 Steel Bridges Across Australia

Metal Spray Supplies Australia reports that thermal spray zinc has been specified for numerous Australian bridge projects, with coating systems designed for 30-year life expectancy in coastal and marine environments.

8. Market Outlook: Zinc & Thermal Spray Industry 2025–2035

8.1 Thermal Spray Coating Market

According to Global Market Insights, the thermal spray coating market was valued at USD 15.7 billion in 2025 and is projected to reach USD 29.5 billion by 2035, at a CAGR of 6.5%. The metals and alloys segment (including zinc wire) dominates material types, with aerospace & defense holding a 34.5% market share.

8.2 Zinc Price Trends

Per SunSirs market analysis, SHG zinc prices in China opened 2025 at 25,846 RMB/ton and closed at 23,276 RMB/ton, a decline of 9.94% for the year. Market analysts from Macquarie Group project that China’s growing refined zinc production — driven by new smelting capacity — may keep prices under pressure through 2026–2027, creating favorable procurement conditions for thermal spray wire buyers.

8.3 Infrastructure as Demand Driver

The U.S. Infrastructure Investment and Jobs Act, EU bridge refurbishment programs, and China’s “New Infrastructure” initiative are driving sustained demand for thermal spray zinc wire. Bridge rehabilitation and corrosion protection represent one of the fastest-growing application segments for SHG zinc wire globally.

9. How to Verify Zn99.995 SHG Zinc Wire Quality

When sourcing Zn99.995 SHG zinc wire, always request and verify the following documentation:

Mill Test Certificate (MTC) per EN 10204 Type 3.1 — must show Zn ≥ 99.995% and all impurity elements below ASTM B833 limits
Certificate of Conformity to ASTM B833-20 (or latest revision)
Dimensional inspection report showing wire diameter tolerance and out-of-roundness
Third-party inspection (SGS, Intertek, Bureau Veritas) — recommended for first orders or critical infrastructure projects
Traceability — batch numbers linking back to SHG zinc ingot source and production records

10. Conclusion: Choosing the Right Zinc Wire for Your Project

Zn99.995 SHG zinc wire conforming to ASTM B833-20 is the gold standard for thermal spray and electric arc spray corrosion protection. For 3.2 mm wire specifically:

For bridge, marine, and infrastructure projects: Always specify Zn99.995 SHG with full MTC. The purity premium is a fraction of the cost of coating failure.
For less critical indoor or temporary applications: Zn99.99 may be acceptable, but verify that impurity limits still meet ASTM B833.
Never use Zn99.9 or ungraded zinc wire for ASTM B833-specified projects — it violates the standard and voids coating warranties.

As global infrastructure spending accelerates and coating performance requirements tighten, the demand for certified SHG zinc wire will only increase. Procurement professionals should build relationships with suppliers who can provide consistent quality, full traceability, and third-party-verified MTCs for every batch.

About ZhenAn International Co., Limited

ZhenAn International is a China-based supplier of Zn99.995 SHG zinc wire for thermal spray and metallizing applications. All products are manufactured to ASTM B833-20, ISO 14919, and DIN 14919:2001 standards, available in Ø1.6 mm and Ø3.2 mm diameters. Each batch ships with a full Mill Test Certificate (EN 10204 Type 3.1). Third-party inspection by SGS, Intertek, or Bureau Veritas can be arranged upon request. We offer FOB Tianjin/Shanghai and CIF delivery to all major ports worldwide.

Need certified Zn99.995 SHG zinc wire for your next project?

FAQ

What does Zn99.995 mean in zinc wire?

Zn99.995 means the zinc wire has a minimum purity of 99.995% zinc by weight — also known as Special High Grade (SHG) zinc per ASTM B6. This is the highest commercially available purity grade for thermal spray wire, with total impurities limited to a maximum of 0.005% (50 ppm).

What is the standard specification for zinc thermal spray wire?

ASTM B833-20 is the governing standard — Standard Specification for Zinc and Zinc Alloy Wire for Thermal Spraying (Metallizing) for the Corrosion Protection of Steel. It covers chemical composition, dimensional tolerances, mechanical properties, and testing requirements.

Why is 3.2mm the most common diameter for arc spray zinc wire?

3.2 mm (1/8 inch) is the standard diameter for electric arc spray systems because it offers the optimal balance of wire feed stability, deposition rate, and atomization efficiency, and is compatible with most industrial arc spray guns.

How long does a thermal spray zinc coating last on steel?

Thermal spray zinc coatings provide 20–40+ years of corrosion protection depending on environment. Marine and industrial environments typically see 20–30 years with proper sealer application; less aggressive environments can exceed 40 years per FHWA and NACE studies.

What is the difference between 99.9% and 99.995% zinc wire?

The key difference is impurity limits. 99.9% zinc allows up to 1,000 ppm total impurities, while 99.995% SHG limits total impurities to 50 ppm. Higher purity means more consistent coating quality, better corrosion performance, reduced nozzle clogging, and full compliance with ASTM B833 and ISO 14919.

What certificates should I request when buying SHG zinc wire?

Always request a Mill Test Certificate (MTC) per EN 10204 Type 3.1 showing Zn ≥ 99.995% and all impurity elements. Also request Certificate of Conformity to ASTM B833-20, dimensional inspection report, and third-party inspection if required.