Guide
What is Galfan? Galfan and Zn-Al coatings explained
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Galfan is a hot-dip coating for steel of about 95 percent zinc and 5 percent aluminium, with a very small addition of rare-earth mischmetal. Galfan is a registered trademark, not a general name for every zinc-aluminium (Zn-Al) coating. SIMO Securon's fence wire carries its own 90/10 Zn-Al coating, which is not Galfan.
What is Galfan made of?
Galfan is a zinc-aluminium alloy used to coat steel by the hot-dip process: about 95 percent zinc and nearly 5 percent aluminium, with a very small addition of mischmetal, a mixture of the rare-earth metals cerium and lanthanum. According to GalvInfo, the zinc industry’s technical information centre, the mischmetal improves how the molten alloy flows over and wets the steel, and makes the coating more ductile. The coating is used on steel sheet and on steel wire, fence wire included.
Where does the name Galfan come from, and who owns it?
The alloy came out of a research project organised by the International Lead Zinc Research Organization (ILZRO) and carried out at the Centre de Recherches Métallurgiques (CRM) in Belgium; ILZRO obtained worldwide patents on it in 1981. Galfan® is a registered trademark. The United States trademark register names its owner as Galfan Technology Centre LLC; GalvInfo’s 2017 note names the Galfan Technology Center, Inc.
Galfan is therefore a trade name, not a general word for every zinc-aluminium coating. GalvInfo notes that zinc-5 percent aluminium coated sheet is also made and sold under other trade names, and coatings with other shares of aluminium exist too. The general term is zinc-aluminium, or Zn-Al.
Which standards cover Galfan and Zn-Al coatings?
| Standard | What it covers |
|---|---|
| ASTM B750 | The Galfan alloy itself (zinc, 5 percent aluminium and mischmetal), in ingot form for hot-dip coating |
| ASTM B997 | Zinc-aluminium alloys in general, in ingot form for hot-dip coating |
| ASTM A875/A875M | Steel sheet hot-dip coated with zinc-5 percent aluminium alloy |
| ASTM A856/A856M | Carbon steel wire coated with zinc-5 percent aluminium-mischmetal alloy |
| EN 10244-2:2023 | Zinc and zinc alloy coatings on steel wire: coating mass, other properties and testing |
A standard listed here says what a coating must meet; it does not mean a particular product meets it. Ask a seller which standard their wire is classified to, and for the test report.
How does a zinc-aluminium coating protect steel compared with zinc?
GalvInfo explains the difference in three steps:
- Zinc protects by sacrifice. If the coating is cut or scratched, the zinc next to the bare steel corrodes first, so the steel does not.
- Aluminium protects as a barrier. It forms a thin, very passive oxide layer, so it corrodes more slowly than zinc in most air, but it gives less sacrificial protection.
- A zinc-aluminium alloy combines the two: better barrier protection than plain zinc, while keeping zinc’s sacrificial protection.
GalvInfo reports field studies in which zinc-5 percent aluminium coated sheet had at least twice the outdoor corrosion resistance of galvanised sheet with the same coating weight, in rural, industrial and marine environments. That finding is about coated sheet of that alloy; it says nothing about any particular fence.
How do you read a coating specification for fence wire?
Three figures tell you more than a coating’s name:
- The coating type: zinc (galvanised), or a zinc-aluminium alloy, with its share of aluminium.
- The coating mass, in GSM: grams of coating per square metre of the wire’s surface. Standard galvanised wire carries about 40 to 60 GSM of zinc. Compare like with like: the same alloy at twice the mass protects for longer.
- Salt spray hours without red rust: how long the wire lasts in a salt spray test to IS 9844 before red rust appears, from a test at an NABL-accredited laboratory.
Ask for the test report behind each figure, and for the standard the coating is classified to. More on how SIMO Securon tests is in quality and testing.
What coating does SIMO Securon use?
SIMO Securon Alpha and Zeta Nova carry a zinc-aluminium alloy coating of 90 percent zinc and 10 percent aluminium: Zn-Al 90/10, 240 GSM minimum on Alpha and Zn-Al 90/10, 120 GSM on Zeta Nova. Pi has a zinc coating instead (Zinc, 80 to 100 GSM, with topcoat). SIMO calls its coating Zn-Al, because Galfan is another company’s trademark: SIMO’s coating is not Galfan and is not sold as Galfan.
Its evidence is SIMO’s own, from NABL-accredited laboratories: salt spray to IS 9844 without red rust of 2,000 hours for Alpha and 1,200 hours for Zeta Nova, and about 200 hours (estimated) for Pi. Coating composition is checked by X-ray fluorescence (XRF), and coating mass by gravimetric and gaseous volumetric methods. Alpha is classified Class A to BS EN 10244-2:2001 and Class W10 to AS/NZS 4534:2006.
| Specification | Alpha | Zeta Nova | Pi |
|---|---|---|---|
| Coating | Zn-Al 90/10, 240 GSM minimum | Zn-Al 90/10, 120 GSM | Zinc, 80 to 100 GSM, with topcoat |
| Salt spray | 2,000 hours without red rust (tested) | 1,200 hours without red rust (tested) | About 200 hours to red rust (estimated from the coating specification) |
| Rated life | 35+ years | 20 years | 10 years |
See SIMO Securon Alpha and SIMO Securon Zeta Nova, and how rated life is worked out on quality and testing.
Galfan® is a registered trademark of Galfan Technology Centre LLC. SIMO Securon is not affiliated with it.
FAQ
Galfan and Zn-Al coating questions
Is Zn-Al the same as Galfan?
Not necessarily. Zn-Al (zinc-aluminium) is the general name for coatings of zinc alloyed with aluminium. Galfan is one such alloy, about 95 percent zinc and 5 percent aluminium with a little mischmetal, and a registered trademark. SIMO Securon's coating is 90 percent zinc and 10 percent aluminium, and SIMO calls it Zn-Al.
Is Galfan better than galvanised wire?
GalvInfo, the zinc industry's technical centre, reports field studies in which zinc-5 percent aluminium coated steel sheet resisted outdoor corrosion at least twice as well as galvanised sheet with the same coating weight, in rural, industrial and marine air. The coating mass matters too: compare the GSM and salt spray hours on a test report.
What coating does SIMO Securon use?
SIMO Securon Alpha carries Zn-Al 90/10, 240 GSM minimum and Zeta Nova Zn-Al 90/10, 120 GSM; Pi has a zinc coating instead (Zinc, 80 to 100 GSM, with topcoat). SIMO calls its coating Zn-Al, because Galfan is another company's trademark. Salt spray to IS 9844 runs without red rust to 2,000 hours for Alpha and 1,200 hours for Zeta Nova, tested at NABL-accredited laboratories.
What does GSM mean on a wire coating?
GSM is grams of coating per square metre of the wire's surface. More coating of the same kind means more metal to protect the steel before red rust starts. Standard galvanised fence wire carries about 40 to 60 GSM of zinc; check the GSM on the test report, not only the coating's name.
Sources
- GalvInfoNote 1.9: Zinc-5% Aluminum Alloy-Coated Steel Sheet (Rev 1.2, December 2017) (opens in a new tab), GalvInfo Center, International Zinc Association
- ASTM B750-22: Standard Specification for GALFAN (Zinc-5 % Aluminum-Mischmetal) Alloy in Ingot Form for Hot-Dip Coatings (opens in a new tab), ASTM International
- ASTM B997-26: Standard Specification for Zinc-Aluminum Alloys in Ingot Form for Hot-Dip Coatings (opens in a new tab), ASTM International
- ASTM A875/A875M-25a: Steel Sheet, Zinc-5 % Aluminum Alloy-Coated by the Hot-Dip Process (opens in a new tab), ASTM International
- ASTM A856/A856M-03(2020): Zinc-5 % Aluminum-Mischmetal Alloy-Coated Carbon Steel Wire (opens in a new tab), ASTM International
- BS EN 10244-2:2023: Steel wire and wire products. Non-ferrous metallic coatings on steel wire. Zinc or zinc alloy coatings (opens in a new tab), BSI
- GALFAN, US Registration 1414721: status and owner (opens in a new tab), USPTO, the United States trademark register
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