So what is ETFE?

‘Ethylene Tetra-Fluoro-Ethylene’ is part of a group of materials called Flouropolymers. Others include PTFE, FEP. They are technically described as plastics due to their material properties – but do not confuse them with traditional hydrocarbon (oil) based plastics such as PolyEthylene and PET – their similarities stop with the term ‘plastic’.

ETFE is made from a mineral called Flourite, traditionally used in the production of Aluminium. It is abundant throughout many continents such as Europe (notably Switzerland and Germany) China, Mongolia, South Africa and Mexico.

The grade quality required for ETFE Films is currently sourced mainly in China.

Flourite

To make ETFE, Flourite is combined with hydrogen sulphate and trichloromethane. These ingredients make chlorodifluoromethane, that by pyrolysis, yields tetrafluourethylene (TFE), a colorless gas, that is joined with ethylene to make the ETFE copolymer. ETFE resin is produced either in a powder form or compressed into pellets and finally extruded into the intended product.

These can range from:

High temperature protective wire coatings  Pipework – ideal for highly corrosive materials  Protective  Heat shrink sleeving  Film sheets for glazing – typically between 60 micron and 300micron thicknesses

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So what makes this glazing film material so special?

its 10 key properties speak for themselves

1. UV and environmentally inert – this film does not break down under the suns radiation, irrelevant of location.

2. Very durable – currently most architects in this new field are quoting a service life of films as over 50 years, but in reality no one really knows just how long it will last for – some say ‘forever’.

3. Very strong – can take 400x its own by weight and can elongate under intense stress (earthquakes for instance) to over 3 times its length, then return to its original shape.

4. Weighs only 1% the weight of glass –enabling the construction of energy efficient multilayer structures. Added to the high light transmissions and life span, at last there is a product available to the building industry that justifies the expense of such structures.

5. Very high tear resistance –holes do not propagate into tears, and easily repaired long term with patches and specialist repair tapes.

6. Very high light transmission – 94%, with no significant degradation over time.

7. Very low reflective index (4%) compared to glass (which is up to 19% typically) meaning valuable light for crop growth or buildings is not reflected back to the sky.

8. Can be formed into films with light properties of:

* Fully ‘natural’ light – transmission in across the entire spectrum including in the UV

* Diffused – over 70% diffused, creating cloud cover conditions that plants and we ‘recognise’. In greenhouses, this enables light to penetrate deep into the crops, and even out crop development. In the build environment, it enables the use of ‘natural’ sunlight that could combat conditions such as Season Affected Disorder, whilst softening the glare of light. very useful in high radiation locations

* UV blocked – IF UV light is not desirable, there are films with various degrees of UV block up to 100

* Coloured Films – if light transmission is not the crucial factor, there are now numerous colour film options – and even the ability to print customer specific designs

9. PROVEN – with 3500ha of this material in Japanese Greenhouses, a centre of earthquakes, some of which is over 30 years old – this is not a ‘new’ product – its just new to the rest of the world. IT is no longer one of Japans best kept secrets!

10. And FINALLY – if all the above wasn’t too good to be true – its classed as a ‘self cleaning’ material – it is a relation of Teflon, used extensively for non-stick cookware. Whether an architect wishing to do away with expensive glass cleaning systems built into the building envelope, or greenhouse growers wanting to REALLY get all the light claimed by the glazing manufacturer – the benefits of this material property are obvious.

No wonder in architecture ETFE is rapidly gaining the reputation as the ‘miracle construction material’!