#5. Layering for waterproofing

So you think it's your waterproof outer jacket ALONE that keeps you dry?

Despite what marketing claims imply, the outer garment doesn't do everything for you, and some understanding and action on your part are needed for the best results. It's the right combination of layers that counts, plus an understanding of 'beading' and 'wicking.'

It's all about moisture management inwards and outwards through all your layers because sweat must be transported outwards ( wicking) and released by moisture vapour transmission whilst 'beading' prevents water from getting in.

This is a complex issue: Are we expecting too much from our garments, allowing moisture to pass outwards while keeping rain from passing inwards and holding warmth in while keeping wind out?

See our diagram left, which attempts to explain this amazing complexity.

KEEPING WATER OUT.

The Gore rain test.Established early 1990s.

Picture right shows the Gore-tex rain test lab introduced in the early 1990s as the 'Guaranteed to Keep you Dry' scheme. All garment makers were required to submit all their designs for approval. Quote Mike Parsons, formerly CEO of Karrimor and Phoenix. "This move by Gore was so important in 1990 that I changed from brand 'x' to become a Gore-tex licensee.

Waterproof garments and outer fabrics differ widely in laboratory-measured waterproofness and so-called breathability, which is moisture vapour transmission, 'mvt' and not air permeability. However, Gore-Tex, eVENT, Neoshell, Pertex, Keela, and certainly Paramo all share one thing: they all rely on the outer textile's water-repellency. This is created by the surface tension of the DWR finish ( Durable Water Repellent). The best-performing DWR compound has been 'Fluoro' (sometimes referred to as PFOA) related. More than 20 years ago, GREENPEACE blew the whistle on using these fluoro compounds, but only in 2022 was this removed from manufactured garments.

Good for the environment, less so for jacket performance! Your jacket now needs more frequent washing and reproofing.

TRANSPORTING YOUR SWEAT. Wicking (often confused with absorption) is also about surface tension, but at the opposite end of the scale to beading on the outer surface of your waterproofs and windshells. Most people and writers assume that wicking is always outward. Sorry, not correct; wicking works in all directions: inwards ( from your exposed base layer sleeve, making you think your jacket is leaking!) and upwards from your socks and leggings, even up into your base layer). It's important to avoid fashion layering practises of leaving under layers and sleeves exposed.  Insert picture 

However, some special fabrics are DIRECTIONAL WICKING ( also known as Denier Gradient), ie, outwards if used and washed correctly, and can be used greatly. Polartec Powerstretch PowerDry and Paramo ( who call all their clothing ‘directional’). 

WICKING (capillary flow) and WATER REPELLENCY (beading).  

Wicking/capillary flow and water repellency, or ‘beading’ on surfaces, is a natural phenomenon occurring in nature all around us in trees and plants.

 "Wicking/capillary flow or its opposite, water repellency (beading on surfaces) occur because of the difference in the surface tension of the water, the fabric and any contaminants like oil or dirt."  

IN SUMMARY;

There are FOUR elements or actions which help keep you warm and dry.

1. The right combination of layers for weather, activity, terrain, and the group's speed. See section #9 on multi-layering.

2. Understanding that wicking works inwards and upwards as well as outwards!

If you layer using the fashion method with the underlayers exposed, you will quickly get wet! This is often mistaken for a leak in your outer garment.

3. Perform post-activity checks ( checking as if you are a plumber to see where the excess moisture is coming from) and do something about it before you go out again!

4. Good garment aftercare, waterproof outer and base layers being critical. Frequent washing and reproofing are needed to maintain beading on your outer garments. Your base layers will not continue to wick unless you wash them with the special base wash compound.

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