Absolute Guide to Buying Waterproof Outdoor Clothing
How to Choose a Waterproof Jacket
Understanding which type of outdoor clothing you need depends greatly on the type of activity and climate you expect to encounter. For instance, a 5k, 2-Layer water-resistant jacket that protects you from light rain on a moderate walk in the South Downs will react very differently to the challenges of a high energy ascent during a sustained downpour in the Scottish Highlands.
With this handy guide, we hope to give you a better understanding of the types of construction and technology available to help you select the right garment for your travels. Buying waterproof clothing need not be daunting - follow our advice and you will not go wrong!
Waterproof vs Water-Resistant
The vast majority of good-quality jackets on the market are technically water-resistant. A wellington boot is waterproof and if youve ever spent the day yomping around in a pair youll know that the thick rubber shell keeps the rain and muck from getting in but on the downside creates its very own micro-climate; often resulting in a pair of soggy socks and sweaty feet by the end of the day. Nothing gets in, but nothing gets out either.
The trick with waterproof clothing is to prevent rain moisture from getting in whilst allowing heat moisture (perspiration) to escape.
This transfer of moisture vapour from the jackets interior, through to the face-fabric where it can evaporate in the open air reduces the build-up of sweat, which keeps under-layers dry and allows you to enjoy high energy activities in greater comfort and warmth.
Every brand has its own way of achieving this but the basic principle remains the same:
It's all about the molecules
In basic terms, each garment features a water-resistant membrane made up of micro-pores (in some cases over 9 billion per square inch!). These pores are so small that a single water droplet is unable to penetrate it. At the same time, a smaller water vapour molecule is able to pass right through, essentially enabling the layer to breathe and drawing sweat to the outside. Think of a one-way street with larger traffic blocked from going one way yet smaller traffic allowed to pass in the opposite direction.
Membrane construction varies in density (pore size) with each garment carefully designed to perform in certain conditions, from light rain to heavy downpours. Each design is then rigorously tested to determine its waterproof rating this provides us with a rough guide as to the level of protection the garment affords and thus the type of activities and conditions it is best suited to.
Static Column Test Waterproof Ratings
The Static Column Test is used to measure agarments waterproofness and provides us with a water column rating (anything from 1K 40K+). The Static Column Test uses a 1-inch diameter cylinder positioned vertically over the material to be tested. Water is added to the cylinder and the point at which the material leaks (measured in mm) becomes the waterproof rating.
So that 5K jacket you got for the South Downs leaked at the 5000mm mark giving it a rating of 5K (or 5000mm). Great in light showers but the density of those pores means it will let in water in a sustained downpour. Thinking of that spring trek around the Black Mountains? Then youre going to want a jacket with a higher rating to ensure dryness.
Theres no hard and fast rule to determining the level of protection afforded by higher ratings as waterproofness is affected by the pressure of water (exacerbated by wind) working upon it.
In real terms, a higher-rated waterproof construction will keep moisture out for longer.
A rough guide to waterproofing...
Protection in light showers. Great around town and casual hikes with no heavy storms in the forecast. Will eventually leek when exposed to sustained downpours.
Great for longer hikes into exposed areas with a good level of storm protection. May leak under prolonged exposure to heavy rain/wind.
A solid level of waterproofing - the kind of jacket the experienced walker and outdoor professional would want in their kit.
High-alpine and expedition level gear. Built with storm-level protection to withstand sustained downpours and high winds. These will give you guaranteed protection under pressure.
What's in a 'layer'?
In order to keep you dry and comfortable a waterproof jacket must be able to repel water moisture from the outside and let moisture vapour escape from the inside.
Construction differs between brands and intended use, with jackets geared towards rock-climbing and winter sports often featuring a more rugged, abrasion-resistant fabric than casual lightweight rain shells. The most obvious thing to look for when choosing a waterproof jacket is the layering these typically fall within three categories: 2-layer, 2.5-layer, and 3-layer constructions.
In each case, these comprise a DWR face fabric with a waterproof/breathable membrane backer (such as Gore-Tex) with the main difference occurring in the liner or innermost layer. Here's a quick guide to understanding the pros and cons of each type:
2 Layer:
A DWR coated face fabric laminated to a micro-porous membrane backer with a separate fabric or mesh liner. The DWR coated shell works alongside the membrane backer to prevent water moisture from penetrating while the inner liner gives you next-to-skin comfort. The downside is that the liner adds weight and bulk as well as placing another layer for water vapour to pass through before escaping through the membrane. Great for everyday rain protection where durability isn't an issue.
2.5 Layer:
A DWR coated face fabric laminated to a micro-porous membrane backer with a printed or sprayed on partial protective layer (in place of a separate fabric liner) to guard the waterproof membrane against becoming clogged with dirt and grease. This provides the wearer with a lightweight and highly packable design and forms the standard waterproof construction for everyday use with a great level of waterproof-breathable protection. The downside is that the added layer reduces the membranes breathability and can decrease durability due to the lack of a separate fabric liner.
3 Layer:
DWR coated face and membrane but with a lightweight fabric laminated on the back side of the micro-porous membrane. This offers the highest performance and most durable construction of the three, making it ideal for mountaineers and outdoors enthusiasts traversing challenging terrain. Downsides are a slight reduction in comfort and flexibility in the fabric. The added level of construction also gives 3-layer garments a higher price point.
Breathability
Refers to the process of Moisture Vapour Transfer (MVT) or in simple terms the ease at which sweat passes through the waterproof membrane. The speed/ease at which this occurs is heavily dependent on a variety of factors not least the individual and the activity being performed but can be determined by the nature of the materials construction. The more porous the material the more efficient the rate of moisture vapour transfer. More technical layers (such as Gore-Tex Pro and NanoPro Membrane) offer a high number of micro-pores (per sq. inch) for rapid MVT. High energy pursuits such as climbing, running, and cycling are better suited to lighter, more breathable constructions that let heat moisture escape faster.
DWR (Durable Water Repellent)
This is a polymer applied to face fabrics that is absorbed into the fibres and causes water to bead and roll off on contact. It provides an initial barrier to rain moisture and works alongside the breathable membrane to prevent water from getting in. DWR coatings can wear off with repeated wear leaving the membrane to do all the work. While a good quality membrane will continue to prevent water from penetrating, the lack of an effective DWR means the fibres can become waterlogged and clogged with dirt and oils. This greatly reduces the membranes ability to breathe which leads to the build-up of condensation which can leave you damp on the inside.
Care for your Waterproof
The micro-porous membranes that sustain your garments breathability can become clogged over time with dirt, grease/oils, and insect repellents. To prevent reducing your clothing's ability to provide waterproof-breathable protection, it should be cleaned regularly and reproofed when necessary.
Follow the link to see our selection of clothing care products, including a range of innovative technical cleaners and waterproofers from Granger and Stormcare. Re-proofers and cleaners can be applied to clothing either in a machine, by hand, or both. Always follow the instructions on the product carefully, as well as the label on your garment.
Cleaning
Do not wash your waterproofs using regular household washing detergent or fabric softener as these products contain chemicals that could clog pores and break down fibres in your clothing's waterproof membrane. However, technical outerwear-specific cleaners feature non-detergent agents and are the best way to maintain your garments outdoor performance.
Firstly, ensure all loose mud and dirt has been swept off the item of clothing using a non-abrasive brush or sponge. Always ensure your machines detergent compartment has no powder left over from your last wash. Try to stick to washing up to a couple of garments at a time.
Re-proofing
Washing it alone will not do enough to maintain your garments waterproofing. If you notice water has started being absorbed by your garment instead of being repelled after washing, or you've been using your jacket or trousers for a while, then it may be time to reproof them.
Always wash your garment first before applying one of our re-proofing products.
If using a spray, apply the fluid from a distance of 6-8 inches evenly across the entire outer surface of the garment. If possible, hang it on a clothes line to make application easier.
After re-proofing, leave your garment to fully dry. Or, if possible, tumble dry on a low heat setting or place on a low heat radiator. A small degree of heat is a great way to help restore clothing's water repellence.
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