Breathability is normally expressed in terms of how many grams g of water vapor can pass through a square meter m 2 of the fabric from the inside to the outside in a 24 hour period.
The larger the number, the more breathable the fabric. Except that this figure is only for the membrane, not the finished article. The construction of the jacket will also have an effect. In a three layer jacket 3L , the membrane the middle layer is bonded to the outer face fabric and a protective internal woven layer.
This is a lighter solution but doesn't protect the membrane as well and also doesn't have such a nice feeling against the skin, often being described as 'clammy'. Generally three layer garments are more breathable.
The last thing to consider is DWR, or Durable Water Repellency, the chemical treatment that is applied to the outside of waterproof garments to make water bead up and roll off. This treatment wears off over time and although its disappearance in no way affects the performance of the membrane, without it rain will sink into the face fabric and significantly impair the breathability of the garment. Therefore in order to maximise the breathability of your jacket you should wash it in special soft detergen t to maintain the DWR and reproof it regularly.
Now that you know what's going on, the following table lists some common membrane brands that you may come across in Australia, along with their waterproof and breathability ratings.
Hopefully this will give you an idea of what to look for next time you are replacing a jacket, pants or boots. This is usually done using a narrow cylindrical tube. Material that is considered to be waterproof must have a rating of at least 1,mm. The majority of outerwear sold for Australian conditions sits at about 10,mm. To put it into perspective the best material goes up to about 20,mm. Gore-Tex is the best but it does not carry a rating however many companies claim it sits anywhere inbetween 25,mm to 40,mm.
While 5,mm is great for Australian conditions if you plan on sitting in the snow a lot you might want to grab a pair of pants with 8,,mm. Unfortunately there is no universal base of measurement and the size of the cylindrical tube and temperature during the test can vary. This means 10,mm waterproof rating on one company's jacket can vary from another company. Often you can tell the difference when you feel the actual fabric. Thick sturdy fabric is going to be more waterproof than thin fabric that feels like paper even when they are both 10,mm rated.
If waterproofing is a big concern for you make sure you always go as high as possible. Most snow fabric is coated with a waterproof spray that can wear off over time. The waterproofing can be reapplied and we usually recommend doing this at the beginning of every season.
We also recomend washing your outerwear with specific outerwear detergent. Outerwear fabric has tiny microscopic fibers that stick up and help water to bead and roll off. When the jacket gets dirty these fibers get pushed down and aren't as effective. If you don't use the correct type of detergent then the fibers can get damaged or rip off.
Breathability is measured by the rate at which water vapor passes through a square meter of fabric over a 24 hour period. This is most often measured in grams. Recent Articles. Tag cloud. What are waterproof ratings? How are waterproof ratings determined? Is a tent with higher HH always better? So which tent ratings are suitable for which conditions?
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