Short answer: Halar (ECTFE) is a thick-build fluoropolymer barrier coating designed for severe chemical environments. It provides exceptional permeation resistance at film builds of 200–1800 µm — far thicker than standard Teflon coatings — and is used to protect chemical process vessels, tanks, pipes, valves and pharmaceutical equipment from aggressive chemical attack.
Halar is the trade name for ECTFE (ethylene-chlorotrifluoroethylene), a fluoropolymer manufactured by Solvay (now Syensqo). It sits in a different category to PTFE and PFA. Where Teflon coatings are typically applied at 25–72 µm for non-stick and moderate chemical resistance, Halar is applied at hundreds or even thousands of microns to create a genuine chemical barrier lining on the substrate.
What makes Halar different from Teflon coatings
The fundamental difference is purpose. PTFE and PFA (Teflon) coatings are selected primarily for non-stick performance, release properties and moderate chemical resistance. Halar is selected when the primary requirement is a thick, impervious chemical barrier — when the coating needs to prevent chemicals from reaching the substrate at all.
Halar's permeation resistance is its defining characteristic. In aggressive chemical environments — concentrated acids, caustics, solvents, chlorinated compounds — chemicals will eventually permeate through thin-film coatings and attack the substrate. Halar's thick build and polymer structure create a barrier that chemicals cannot penetrate under normal operating conditions.
Key properties of Halar (ECTFE) coating
| Property | Halar (ECTFE) | PTFE (for comparison) |
|---|---|---|
| Film build (DFT) | 200–1800 µm | 25–35 µm |
| Continuous service temp | 150°C | 260°C |
| Chemical resistance | Exceptional barrier — very low permeation | Good general resistance |
| Primary function | Chemical barrier lining | Non-stick / release |
| Holiday testing | Standard (required) | Not standard |
Temperature considerations
Halar is rated for continuous service at 150°C — lower than PTFE and PFA at 260°C. This means Halar is not the right choice for high-temperature applications. It is selected for environments where chemical aggression is the primary concern and operating temperatures remain within its service range. For combined high-temperature and chemical resistance requirements, PFA is usually the better option.
Film build: the 200–1800 µm advantage
The ability to build Halar to 1800 µm (1.8 mm) is what makes it a true barrier lining rather than a surface coating. At these thicknesses, the coating provides mechanical durability, impact resistance and a physical wall between the chemical environment and the steel substrate. This is why Halar is specified for the inside of chemical process vessels, tanks and piping — applications where thin-film coatings would not survive.
How Halar is applied
Halar application is a multi-stage process that requires specialist equipment and expertise. It is significantly more complex than standard PTFE or PFA application:
- 1Abrasive blast the substrate to the required surface profile
- 2Preheat the substrate to 290–400°C
- 3Apply Halar primer and bake
- 4Apply Halar topcoat via electrostatic spray (first coat)
- 5Build subsequent topcoats using hot flock application to achieve required thickness
- 6Final cure and holiday testing to verify coating integrity
The two-part system (primer + topcoat) and the combination of electrostatic and hot flock application techniques require equipment, skill and process control that not all coating applicators can provide. This is specialist work.
Typical Halar applications
- Chemical process vessels and reactor internals
- Storage tanks for acids, caustics and solvents
- Pipes, valves and fittings in chemical process lines
- Pharmaceutical processing equipment
- Semiconductor manufacturing components
- Heat exchangers and scrubber systems
- Any application where chemical permeation to the substrate must be prevented
Holiday testing: verifying coating integrity
Holiday testing (spark testing) is standard practice on Halar coatings — unlike PTFE or PFA, where it is not typically performed. A holiday test uses high voltage to detect pinholes, voids or discontinuities in the coating film. Because Halar is applied specifically as a chemical barrier, any defect in the film could allow chemicals to reach the substrate. Holiday testing verifies that the coating is continuous and defect-free before the equipment enters service.
Not all coating applicators can handle Halar
Halar requires specialist equipment (electrostatic spray guns, hot flock capability, large ovens for substrate preheating to 290–400°C), process expertise and holiday testing capability. Many fluoropolymer applicators only handle PTFE and PFA. If you need Halar coating, verify that the applicator has specific experience with ECTFE systems and the equipment to apply them properly.
Halar coating from AST
AST applies Halar (ECTFE) as part of our full fluoropolymer coating range. As the only Chemours-licensed industrial fluoropolymer applicator in Australia, New Zealand and South East Asia, AST has the equipment, process capability and technical expertise to handle Halar projects — from individual valves and fittings through to large chemical process vessels.
All Halar work is holiday tested as standard, and every project is covered by our lifetime workmanship warranty. If you are specifying Halar for a chemical or industrial application, talk to us about your requirements.