Why does the outer of my FurTech jacket get so wet?

 

 In heavy rain or persistent drizzle water coming from the outside mixes with vapour coming from the inside, which condenses in the cold outer fabric. The fabric has a sentiment change from hydrophobic to hydrophilic. This is inevitable - it's just the laws of physics - and it helps the lining stay dry. This is because water likes to stick to water so any droplets in the warm and hydrophobic furry lining are picked up by the outer fabric and moved away from your body.

When the outer saturates on a conventionalwaterproof the membrane prevents condensation from the inside from being moved outwards. This is one reason why FurTech works... and is probably why animals don't wear their skins on the outside!

(The photo above was taken after an hour of walking in the rain. The weather only got worse, yet I remained dry inside.)

Comments

[Jill]

Hi,

Great, informative site! Very interesting about sentiment change.

One question: when the outer wets out doesn't this effectively stop the breathability of the system? With membrane jackets a poor DWR and wet-out turns a WPB into a plastic bag. Doesn't the same thing happen with a wetted-out windproof fabric - water fills the interstices, blocking air and vapour passage?

[Andy]

Good question!
When the outer saturates, vapour from the inside is likely to condense on the cold wet fabric, releasing its latent heat of condensation. This energy may encourage water vapour molecules to escape from the outside of the fabric.
More significantly, wind and body heat can also drive water vapour to escape from the saturated outer fabric. This is a drying process when it's not raining. When the air is mostly saturated drying may still occur from the down wind portion of the fabric where the air is at a lower pressure and unsaturated. Microporous membranes dry much slower than our fabrics because they can't move liquid water (condensation) outwards.