Your Gore Questions Answered

Last week we asked you what you you wanted answered about Gore-tex waterproof / breathable boots - see this forum thread - then we wrote down all your questions on microfilm, took a plane to Gore's secret mountain-top research and testing centre in the Bavarian Alps, clung to the underside of a cable car for ten minutes then finally cornered Gore's top footwear technicians and made them drink Weissbier till they'd given us the answers.

So, real questions from real people. Here's what they told us:

Q: How will I know if the Gore-Tex membrane is worn out?

Gore footwear is tested for abrasion resistance, flexing - for 300,000 flexes in water - and twisting. Gore say they offer a lifetime guarantee for waterproofness and will take appropriate action if a boot leaks because of a problem with the membrane. In other words the membrane shouldn't wear out through simple flexing and use, though it can still be punctured or damaged if the boot isn't looked after. (Editor's note: my calculation is that 300,000 flexes is equal to about 500 kilometers of walking assuming around 60 double paces per 100 metres, remembering that each boot flexes every other step).

Q: Why doesn't anyone make Gore-Tex socks or removable boot liners? Is there a technical reason?

Gore says there's no particular technical reason that this couldn't be done, if one of the manufacturers they work with asked them to develop such a technology, though at the moment no-one has, but technically it would be possible. (Editor's note: Berghaus used to sell a Gore-Tex sock, but it was bulky, uncomfortable and poorly shaped with too many seam)

Q: How many times can Gore-Tex flex before failing?

The Gore-Tex test centre has a flex tester which simulates walking through water, flexing the boot at the normal flex point behind the toe. An electrical sensor inside the boot detects if water's getting in and stops the test. Gore say that the normal number of test cycles is 300,000 and in their experience, if a boot doesn't leak within this time, it shouldn't leak at a much higher number of flexes. Normally, they say, if a boot does leak a the flex point it's because a lack of care has allowed the leather to harden and crack so a sharp edge can rub against the membrane and abrade it leading to leaking. Because of this, stiffer boots, which flex less, sometimes last longer.

Q: Could you reinforce the flex point to prevent this happening?

Gore says it supplies manufacturers and they are responsible for the designs, no-one has ever asked them to do this, but a manufacturing partner could do this if they chose to.

Q: Is it right that if just one thorn penetrates a Gore-lined fabric boot it will leak?

Gore says yes, but then if you drive a nail through a Wellington boot, that will leak too and the same is true of leather boots. If you hole the membrane it will leak, but that's life and not a problem unique to Gore.

Q: The outers of my Gore-lined boot allow water in by capillary action and wicking - they are four years old. Any comments?

Gore says all materials including laces and stitching as well as the materials used for uppers, both leather and fabric, are now tested to make sure that they don't wick. Laces and stitches are abraded to simulate use, so new Gore-Tex boots shouldn't wick water up over the ankle cuff.

Q: How breathable are the other fabrics used in Gore-Tex boots?

Gore say that they test all the different components of the boot and ultimately lab tests are designed to make sure that the whole boot functions as a unit and meets breathability standards. Construction is important too - in the past some factories have used glue to hold the uppers together before stitching or even glued the membrane to the outer. Glue, unfortunately isn't breathable, so if there's too much of it, performance suffers. But the bottom line, they say, is that any fabric or leather used with current Gore boots should meet their standards of breathability of the breathability of the whole package will be compromised.

Q: Is it possible to alter the fit of Gore-lined boots using a 'rubbing bar' to expand tight spots and accomodate things like bulky toes, big toe knuckles etc?

The Gore technician said that he wouldn't advise anyone to do this with a Gore-lined boot, though he wasn't absolutely certain that it was impossible, he didn't think it was a good idea. So no.

Q: Why are Gore boots more expensive than those equipped with other waterproof liners?

In the course of a day with Gore, it became apparent that they spend an enormous amount on research and development and working with factories and manufacturers to make sure materials and standards meet their requirements. The programme which has produced the new XCR boot liner cost a reported £10 million.

All the materials used in Gore footwear are tested and approved by Gore, actual boots are then tested in pre-production stage, field tested when in production and samples both from shops and the factory are also regularly assessed. There are five laboratories across the world and in 2001 Gore says that they fully tested 3300 pairs of boots, did 422,412,780 flexions in water and assessed 3000 raw materials. The bottom line is that whether you believe Gore-Tex lined boots are the cats whiskers or not, the company invests a lot of time, effort and money in making them as well as they can. Either that or they're telling shameless porkies. The company's annual revenue, by the way, is around $1.3 billion and they have 30 different patents covering their footwear products.

Q: Are leather-lined boots more durable?

Gore says that in their tests it is actually less durable, in terms of abrasion, than some of their best performing fabric linings and that any boot made using Gore-Tex meets their standards for breathability. The main attraction of leather linings, they say, is that they are perceived as being more 'upmarket'. So there you go.

Q: Do Gore view the customer as a pain in the butt?

The Gore man smiled enigmatically at this one and shrugged... Journalists more like, we reckon.