John W. Cropper

ePTFE (aka Goretex)

ePTFE (aka Goretex) - John W. Cropper

If you search through the wardrobes of your house, you are likely to have some. The waterproof fabric known as Gore-Tex is a technological marvel – it lets sweat and moisture out, but protects against wind and rain. It’s smooth to touch, it’s a multi-billion dollar industry – and it should have been ours!

This is a sad tale, another near miss and another lesson on protecting intellectual property. It’s also a good lesson in how patent law works, and what inventors need to think about before they go public with their ideas.

In 1966, in New Zealand, one John W. Cropper developed and built a machine that could create a material called ‘expanded polytetrafluoroethylene’ (or ePTFE for short). Cropper was an engineer, building machines to manufacture industrial components, when American chemical giant DuPont approached him and asked if he could build a machine to manufacture Teflon tape. That’s just what he did.

Before we go any further, we should explain this stuff. PTFE is essentially a product which we also know as Teflon, but stretched. Teflon, as it is now widely understood, is a brand name for a substance that is very slippery and non-reactive. It coats pots and pans, and often politicians. If you work out how to take PTFE and stretch it, then it will form a tape, the sort of thing plumbers use in tap joints to stop them from leaking. Stretch that tape sideways and it forms an expanded version – like a wide strip of Teflon. It keeps many of its properties but adds some new ones – it’s now full of about 3 billion tiny holes per square centimetre, but they are about 1/20,000 the size of a water droplet. So liquid water can’t get through, but water vapour molecules, which are much smaller, can. For those who can remember fourth-form chemistry, it’s a long chain (poly) with four (tetra) atoms of fluorine (fluoro) hanging off two carbon atoms with two hydrogen atoms attached to each (ethylene).

You can find a more comprehensive description of it here.

The almost magical properties of this membrane make it sought after and suitable for a number of uses – we all know it from its use in clothing, where the ePTFE is the core of a layered set of fabric which is waterproof yet breathable, fantastic for the outdoors. It’s also used in the medical industry – it turns out that human body tissue can grow through it, effectively making it a scaffold for the body – and for protecting old manuscripts. But its most valuable feature today is probably its name. Gore-Tex is a trademarked brand of W. L. Gore & Associates Inc, whose founder, one Wilbert Gore, came up with a process for creating ePTFE in 1969. You’ll note that was three years after our Cropper had invented his machine to do the same thing – so how come we aren’t all wearing Cropper-Tex?

It’s clear and undisputed that Cropper made his machine, and the first ePTFE tape, three years before Gore did. But Cropper didn’t patent his machine or his process; instead he decided to try to keep his method a secret. In some ways, that’s a valid decision – when an inventor comes up with an idea, they can choose a number of ways to protect it. A patent means that the world gets to find out all about the idea, but that the inventor has a 20-year head start on commercialising its use. A trade secret means that no one gets to find out the secret behind the invention, and the inventor can do whatever they want with it for as long as they can keep it a secret. Coca-Cola is probably the most famous example of a product that remains a trade secret – if you can find out the recipe you are free to make it yourself.

Looking back, Cropper says that if he knew then what he knows now, he would have taken out a patent, but he was under the (mistaken) belief that he couldn’t patent a process. So instead, he manufactured the machines and asked customers to keep its process secret. It was a unique machine, producing better quality, softer Teflon tape than anyone thought possible. In fact Cropper believes a UK company attempted industrial espionage – sending someone to work for him to find out all about its manufacture and methods.

In 1968, Cropper sold one of his machines to a US company – the Budd Company. He contractually bound them to secrecy, but the folks at Budd consulted with a third party about how they might make Cropper’s machine more effective, and there is some suggestion that secrets were leaked.

Not making the same mistake, in the early 1970s Gore filed for a patent for his process and the product, and it was granted. He set about commercialising and marketing Gore-Tex and it quickly became clear it was going to be a big money spinner. The US Army – and your dad – had been hunting for a lightweight, waterproof, breathable material for years.

In 1979, Gore found out that another company (Garlock) had been using the Cropper-invented machine to churn out an alternative product to Gore-Tex, and sued them for breach of patent. Garlock, using Budd’s machine and Cropper’s invention, defended the suit, claiming that Cropper was the original inventor of the ePTFE process so they had a right to make it. The US courts originally sided with Budd and Cropper, saying it was clear that the process was first created by Cropper. However, with so much at stake and a legal case to make, Gore appealed the decision, and the US Court of Appeals, after much debate, many expert witnesses and an examination of the facts, overturned the original finding. They essentially found that because Cropper had kept his invention a secret, he had no rights when someone else created their version of the product. In fact, by continuing to create the alternative product, Garlock were now infringing on Gore’s patent, and they were forced to stop. Gore was legally recognised as the inventor of ePTFE, and went on to win awards in recognition of ‘his invention’. Cropper kept on working, among other things making parts for Fisher & Paykel and inventing a new type of macadamia nutcracker, but he can’t help wondering what might have happened if he’d known a little more about patent law at the time.

You might call foul here, and try to make an argument that Cropper was hard done by – perhaps he was, and New Zealand missed out on the multibillion dollar industry that Gore-Tex became. Fundamentally, though, it’s a lesson that while creating the original invention is important, equally important is how you set about commercialising and protecting your idea. Without careful consideration of the right approach, you too might come a Cropper.

More Information

More detail on the court case