We have differnt levels of waterproof rating and not everybody need the highest, 20 000 mm. It is good to know that the higher jacket´s waterproof rating the longer the fabric will remain waterproof. Fully waterproof jackets are made with a waterproof membrane or coating with taped seams. A waterproof membrane is a thin layer that has lots of microscopic pores which are big enough to allow water vapour to be released but small enough to stop water droplets getting in.
0-1 500 Dry conditions and light rain or snow
1 500-5 000 Average rain
5 000 – 10 000 Moderate to heavy rain
10 000– 20 000 Heavy rain – extreme weather conditions
The ability of a jacket to allow perspiration to escape is as important as not letting water in, especially if you will be doing anything energetic. If a waterproof jacket is not breathable, sweat will be unable to escape, making the wearer feel damp. It’s common for people to feel as though their waterproof has ‘leaked’ when in fact it’s perspiration from inside they are feeling. In addition to a breathable membrane, other features can make a jacket even more breathable. Features such as pit zips and mesh lined pockets are ideal for added ventilation.
|1 000||Low activity|
|5 000 – 8 000||moderate active and pause were you take off your garment|
|10 000 – 20 0000||very active|
For a jacket to be 100 % waterproof it will also need to have sealed seams. Sealed seams are heat sealed seams that stop water coming through the stitching. It is particularly important that you choose a jacket with sealed seams if you will be in heavy, prolonged rain. For a jacket to be more than enough waterproof – everyday use in moderate rain it can be enough to choose a jacket that have critical seam sealing, this means that the seams are heat sealed, like at sealed seams but only at critcical spots, eg shoulders
The membrane is stretched so heavily that it gets micro cracks.
1 cm2 membran can have more than 1 billion pits.
One pit is 20 000 times smaller than a water drop.
One pit is 700 times larger than a steam molecule.
Not all fabrics are made for keeping water out, nor are they good at evaporate the sweat, instead they should keep you warm and well temperatured.