Spectra Line

All You Wanted To Know But Were Afraid To Ask

Spectra line is mainly used by sport kite and power kite enthusiasts. They fly everything from small 2-line Deltas right up to large traction kites used by surfers and land-board riders. This line material is so good for this purpose that it is also used for those experimental giant parafoils which help to tow large ships and thus cut down their fuel costs. Mind you, those lines are as wide as your thumb!

If you ever come across a single-line kite flier using Spectra, you can bet they are up to something interesting, like setting altitude records! Or perhaps they just like the low weight of this material. Very large kites need quite a weighty and bulky spool of line otherwise.

Are you ready for some concentrated info on Spectra line? After digging around a little, some interesting facts popped up. Just to be different, I've decided to use a Question / Answer format to present it all...

Try this if you're not living in the U.S.

Q: What is Spectra?

A: Spectra is a trade-name for a very high molecular density form of polyethylene. Like other synthetic materials, it is made in other forms beside long flexible line. Like bullet-proof vests! Polyethylene, by the way, is the most widely used plastic on the planet. Think 'plastic bags'.

In Spectra, the very long chains of molecules are aligned which gives the material its very low stretch and high strength. In fact, the strength-to-weight ratio is more than 10 times better than steel.

Q: How does Spectra compare with other kite line materials?

A: It is more expensive than most other line materials. Such as cotton and nylon. For a given strength, it is much thinner and lighter than the other commonly used line materials. That explains why it has been used for altitude record attempts! In fact, Spectra is about 1/3 the diameter of nylon line of the same breaking strain.

On top of this, Spectra has very low stretch, which is important for flying steerable multi-line kites. Can you imagine steering your car with a couple of big rubber bands tied to the steering wheel...

Q: When was Spectra invented?

A: Gel-spun polyethylene was invented by DSM High Performance Fibres of Holland in the 1990s. At that time, the company called the material Dyneema. It was later licensed to Allied Signal in the U.S. and Toyobo in Japan. Dyneema is very similar to Spectra, and is used a lot with paragliders. Spectra is the trade-name used by Allied for its version of the material.

Q: How is Spectra line made?

A: Gel-spun, that's how. OK, I'd never heard of that either... While the hot polymer is still in a gel state, it's forced through a rotating spinneret to form individual strands which bond together as they cool. After this the strands pass through an air-drying and cooling stage before being cooled even more in a liquid bath.

It's no coincidence that spiders spin their incredibly strong web material the same way. Man copies nature.

Q: Who makes Spectra line?

A: Spectra is the trade-name for polyethylene kite line coming from Allied Signal, a U.S. manufacturer. Actually, the name 'Spectra' is a registered trademark for the material, held by Honeywell International. This company was known as Honeywell Incorporated before being bought and re-named by Allied in 1999.

Q: Does Spectra have any special properties?

A:

• It floats on water! That's more of interest to fishermen rather than kite-fliers of course.
• It has a rather low melting point. 147°C (297°F) to be precise, which is not a lot hotter than boiling water! For this reason, it must be kept well away from lines of other types while in the air. A back and forth sawing action by the other line will soon friction-heat the Spectra to the point of failure. Bye-bye kite!
• It is naturally very slippery, which multi-line fliers love since crossed lines don't inhibit the control of the kite.
• It is susceptible to 'creep', meaning it will very slowly get longer if it is held under continuous heavy tension. Kite fliers would not notice this, I'm pretty sure.

A colorful Delta sport kite down at the beach. There's a good chance it's flying on Spectra lines...

Photo courtesy of Rick Audet.

Hope you found some of this info on Spectra line interesting, useful or even both!

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