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Waterproof zip for performance outerwear
When using a jacket containing one of the latest water resistant zips (fig 1a), and having spoken to several friends who have used these zips, there was a general consensus that they leaked.
For my undergraduate student project I set about quantifying the leakage observed by users of the water resistant zip. In doing so I discovered a failure mechanism which occurred during movement or gaping of the zip.
The zips are nominally water resistant because two stiffened silicone membranes positioned just above either set of zip teeth meet when the zip closes and provide a water resistant seal or cover above the zip. How do the zips fail? When such a zip is compressed along its length i.e. there is motion in the upper body such as power walking or climbing that tends to compress or bend the zip, the two halves of the membrane separate enough (~ 0.3 mm) to allow water in. Clearly a zip that is only water resistant when not compressed i.e., when the user does not move, is not an effective product for mountaineers and outdoor enthusiasts.
Having found the problem and cause of the leakage I decided to see if there was an alternative, more water resistant, fastening device that could be used in a jacket. I initially looked around the outdoor market particularly at fishing and diving kit where near waterproof zips are already in use, but the weight of the zips and the force required to operate them means that they would be total impractical for use in mountaineering jackets. It was the stationary market where I found my ideal fastening device, a zip used on an A4 plastic file bag (fig1b); it uses a tongue and grove method of joining the two halves, overlapping each edge in a continuous fashion.
To test the stationary zip against the market zips I constructed an experimental rig (fig 1c) which simulates what happens during use, it uses a rotating finger to apply pressure from the inside of the jacket to simulate usage or motion and a spray of water to simulate rain.
I compared the plastic-file zip and a current market water resistant zip on the test rig and showed the water resistant zip leaks whilst the file zip remain water tight.
The file zip has a smooth sealing mechanism and is durable, the only real problem occurs when in the closed position part of the zip can come apart, this does require a huge amount of lateral force and a simple reopening and closing of the zip soon sorts it out.
So far the file zip has only been incorporated into a custom pocket so that it could be tested against the water resistant zip on the experimental rig. Organising a donor jacket so it can be put in to a real dynamic mountaineering test situation is the next step.
Images
Image I
Video
No video has been submitted with this project.
Notes
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I am a student from the University of Leeds who has an interest in staying dry outdoors! I am currently working on a PhD project; I am a member of the Performance Research Clothing Group in the School of Design and so am in an ideal position to further develop my zip concept.
Comments
Hi Euan,
thanks for the input. The next stage of my project is to test the zip in real life and compare it to water resistant zips currently on the market.
Hello Barney,
Nice to see that someone I know has submitted an idea. As a user I’ve more often found that wind penetration not water penetration was the biggest problem with these zips. Another problem is in just how resistant they are to being opened and closed – they typically require two-handed operation!
As a sportswear designer I recognise that possibly the largest problem with these zips is their stiffness. The genuinely waterproof zips used in dry suits and on hovercrafts aren’t used in other areas of apparel because they are too inflexible. Stiff zips look terrible because they don’t drape well (they create large buckling) and they’re uncomfortable if they’re not strategically placed.
I guess ziplock type zippers for apparel have been experimented with in the past but haven’t proven durable enough. Scaling them up may solve this, but may result in too much friction of the zipper slider. Adding PTFE coatings to working parts maybe a solution not tried in the past, but this would need to be a localised application (around the zip track but not a the sides) because PTFE can’t be reliably laminated to other materials.
Good luck with it,
Oliver
I would like to speak to you with a view to putting your zip into production.
I am an experienced invention promoter and you can see my site inventors-showcase ltd - I will finance this project 100%.
I can’t see what all the fuss is about! If you go into any supermarket you can pick up freezer bags that have waterproof zipper style fastenings. Aren’t these designed to stop water leaks? So as such, couldn’t the technology be side-styled to fit on outdoor clothes.
The trouble with this design is that the fasteners have to be closed at one end and thus would restrict the styles of jackets to short and mid length fasteners.
As my wife just pointed out to me, they would be waterproof, windproof and airtight, so the pro’s far out way the cons.
Just wanted to say I find your blog very informative. Thanks for writing 
Thanks for the post. Can you give me any idea about,water resistant zips currently available in the market?
i am currently working on a waterproof flexable medical boot for animals. i have pattent pending on my designs but still have a problem finding a siutable zip,i would be very interested in any ideas you might come up with.I too have looked into a4 type zips and diving zips and can see what you are getting at. thanks.keith
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I suppose my first question would be: is the zip strong enough to cope with use on a mountain jacket? Maybe you could look into different materials to make the folder zip stronger if not..