Fabrics

Waterproof

We have different levels of waterproof rating, and not everybody needs the highest, 20,000 mm. It is good to know that the higher a 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 and extreme weather conditions

Breathability

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.

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 waterproof enough for everyday use in moderate rain, it can be enough to choose a jacket that has critical seam sealing – this means the seams are heat sealed, like sealed seams, but only at critical spots, e.g. the shoulders.

The membrane is stretched so heavily that it gets micro cracks.

  • 1 cm² of membrane can have more than 1 billion pores.
  • One pore is 20,000 times smaller than a water drop.
  • One pore is 700 times larger than a steam molecule.

Warming fabrics

Not all fabrics are made for keeping water out, nor are they good at evaporating sweat – instead they should keep you warm and well tempered.

  • LMP 240
  • LMP 160
  • Powerstretch
  • Cotton
  • Down