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jmyers 10-21-2008 05:39 PM

Waterproof/Breathability - CONFUSED/EXPLAINED
Can someone explain to me the waterproof and breathability number given to jackets? Thank you.

Kjerstin Klein 10-21-2008 06:30 PM

Waterproof/Breathable EXPLAINED
Since the fabrics today are so technical it is easy to get confused by the jargon. The key thing to remember is that 2 things make you wet on the slopes. First - ambient moisture, the moisture in the air that can come in the form of SNOW, RAIN and even FOG and Second internal moisture, this is the moisture that comes from sweat.

It is easy to make a jacket waterproof, a plastic sack is waterproof. What is hard is to make it waterproof AND breathable. The breathabiltiy of a jacket is the measurement of how much moisture vapor can escape from the jacket. This is measured in grams of water vapor that can pass through a square meter of fabric in the space of 24 hours. This formula is written as g/m2/d and abbreviated as simply g or gm.

Now different coatings and laminate layers add to the external weather protection of a garment but the over all water resistence of the fabric itself is measured by suspending a tube of water over the fabric to determine how many millimeters (abbreviated as mm) of waterpressure the fabric can withstand before the water begins to leak through to the other side.

Keep in mind many factors go into how dry you stay while you ride. The quality of the garment is found in more than just the numbers. Let me know if you have more questions along this line!

Ride Hard!

jmyers 10-21-2008 06:36 PM

Thank you so much! I get very confused by all the numbers and wonder the actual effectiveness of the kacket. I am looking at a DC jacket with the following info:

Material: Exotex 5000
Waterproof Rating: 5K
Breathable Rating: 5000g

It is said to be super waterproof and breathable, does this make sense?

landonk5 10-21-2008 08:07 PM

5k is on the lower end but it'll hold up pretty well. My pants last year had a 5k waterproof rating and I survived. But generally you're going to want soming around 10k-15k waterproofing and breathability.

PaoloSmythe 10-22-2008 04:42 AM

my understanding of the ratings whose units are expressed in millimeters is as follows.

imagine an area of fabric about the size of your average droplet of liquid. now imagine that droplet being 5000mm tall. that is a 5000 rating of water 'proofness'.

as far as breathability goes.... my memory fails.... presumably if the same logic as above was applied, the preferred rating would be smaller.... you don't want to sweat 5000mm of body juice before it is allowed to escape your clothes!

yeah i got nuffink! fekkin jet lag.... but i know somewhere that does:

Ellis Brigham Performance Fabrics Glossary

Kjerstin Klein 10-22-2008 11:42 AM

Exotex 5,000 Slope Worthy Value
The DC Shoe Co. Makes some great gear. Personally, I love 'em. Exotex 5,000 is their opening price point weather protection but at that price point they seam seal all of the critical seams - meaning those seams that are most likely to leak are sealed shut with a special tape. The 5K stands for 5,000 mm of water resistance and the 5,000 g is the breathability. For most conditions that is more than sufficient and at the price you can't beat it.

The real question is what are you going to be doing in the jacket and will the basic level of weather protection be enough. If you are hard core - stay out in the rain all day 5,000 mm probably isn't going to be enough to keep you dry. If you ride really hard, hike the pipe, do the back country etc. then 5,000 g breathability may not be enough - but then that is what you have vents for!

If you like the jacket I'd say go for it - it is a good deal and should cover you in all basic conditions. If you find it just isn't keeping up with what you need next year you can invest in something with a better rating and keep this one for back up.

Make sure to wash the jacket regularily - this will help to keep the weather protecting matterials at the surface and keep the pores of the jacket open so it can continue to breath.

Layer properly under the jacket so that you have a good 'moisture management' system going to aid in with breathability.

If you need help on either of these points or have further questions on the jacket you know where to find me!

Ride hard!

vtecbrown 11-13-2008 08:14 PM

That's an interesting point about the regular washing of the jackets/pants. I have heard elsewhere (either on this forum or just around) that washing should be done minimally to not wear out the "waterproofiness". There are special soaps to protect against this. Let me know if I'm wrong.

Kjerstin Klein 11-13-2008 09:57 PM

Washing Out Waterproofing
You aren't wrong - just don't have the whole picture. Weatherproofing, depending on the quality of the garment, comes from a combonaiton of several components. The outermost aspect of weatherproofing is the DWR layer - Durable Water Resitant layer. This is typically a spray-on or wash-in liquid fabric coating and is what is responsible for the beads of water you see when you are sitting on the lift. The quality of DWR layers varies greatly and is effected by washing in two ways. First dirt and oils that cling to it will decrease its effectiveness and may allow water to penetrate instead of beading up - so washing will help. Second these coatings will 'sink' into the fabric after time leaving less on the surface to do battle with the weather. The heat from washing and drying will help bring this to the surface again.

The bad news is yes, this coating will eventually wash out - again the wash-out rate will depend on quality. I saw one statistic that said that mid quality DWR coatings should last for about 27 washings. That is a lot of washings in my book. At any rate you are correct about using the right wash - sport specific wash like G-Wash will go a long way to protect the DWR layer. There are also some products that wash in that will replace or at least extend the life of the DWR to some degree. The key is to buy quality and take good care of it.

As far as the other weatherproofing layers the most common is the waterproof/breathable layer. This is a porous membrane that is either laminated to the back of the fabric or a free-floating layer but either way the pores will stretch and give with use and eventually let moisture through. The action of washing and the exposure to heat and water will cause those pores to reconfigure, re-establishing the like-new quality of the membrane.

Hope you enjoyed your crash course on fabric technology!

outphase84 11-25-2008 10:17 PM


Originally Posted by PaoloSmythe (Post 73578)
as far as breathability goes.... my memory fails.... presumably if the same logic as above was applied, the preferred rating would be smaller.... you don't want to sweat 5000mm of body juice before it is allowed to escape your clothes!

You reversed it a bit here.

Breathability is how much moisture it can move away in a given amount of time. Usually expressed in grams per square meter per hour. 5000gm would mean that you can sweat up to 5000gm^2 and the fabric will breathe it out so to speak, but any more than that and you will start to get wet. Just like waterproof rating, higher is better.

Kjerstin Klein 11-26-2008 03:01 AM

Bigger Is Better
Outphase84 has it right - the higher the breathability number the better. It is easy to make something waterproof - a plastic bag is waterproof. It is also easy to make something breathable - a wool sweater is breathable. The trick is to make something both waterproof AND breathable. You chemistry types would love the fabric industry! It is pretty cool what they are able to do these days and we in the snowboard world are lucky to be on the cutting edge of the industry. Truly - we get some of the best stuff - straight from NASA to your bod!

To make a fabric both waterproof and breathable they use a combination of liquid coatings and laminate layers. The coatings I have already talked about - they create a barrier that does not allow water droplets (the liquid form of water) to soak into a garment. The laminate layers are key however because they are made of a a porous material that stop water droplets from getting through but allows water [I]vapor[I]to pass. Sweat, by the way, is water vapor, or steam, the gas form of water.

So the key is in the rating. It is hard, and therefore expensive, to make a stable laminate layer that has enough of these tiny holes (pores) to allow the garment to breath effectively. The more holes the better you breath. The more holes, the higher the rating.

Ok, I realize this is a totally over-simplified explanation of some of the most advanced fabrics on the planet but it should help with your basic understanding of the breathability side of the equation.

One thing to keep in mind is that breathability is only for moisture vapor. That is why what you layer with is so important. If you have sweat that builds up so you are dripping wet that sweat isn't going anywhere. You need to layer with wicking layers that draw the moisture away from your skin and will allow that moisture to evaporate through those little holes we just discussed. Anything that feels wet to the touch when you take it off is not a wicking layer.

Wicking layers spread the moisture out over a large surface area and will feel essentially dry to the touch even when they are saturated. Fabrics that wick are true performance fleece (no not the junk you buy at the mall), constructed hollow core fabrics and some treated natural fabrics but NOT COTTON.

Aside from leaving you feeling waterlogged any sweat that builds up will suck all of the heat out of you. The first rule of keeping warm is keeping dry. So ditch the cotton hoody for the slopes, layer with stuff that wicks and stick gear that breaths.

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