THE ANATOMY OF A SHELL JACKET

ANATOMY OF A SHELL JACKET

Text: Emma Carlsson / Photo: Emelie Voltaire When the wind blows cold or the promised sunshine turns to rain, you’ll thank yourself for the shell jacket you hurriedly threw into your backpack before heading out. But what is it that makes the shell jacket the last word in weather protection, and how does it work? Come with us as we take a closer look at the fibres and discover all the secrets that make shell jackets so effective in keeping the weather out but the heat in.

DWR

A Durable Water Repellent finish, or ’DWR’, is a water-repellent surface treatment that causes the rain to bead on the jacket the rain bead on the jacket before it runs down down off the surface. It works just like the Teflon coating in a frying pan. Been a while since you’ve caught a glimpse of pearl-like rain drops on your coat? Have a look at ’Washing 101’ for advice on how to re-impregnate your jacket

Breathability

No less important than managing to keep the rain out, a jacket has to be able to breathe. This stops you getting wet inside the jacket. The breathability of a garment is often measured in g/m²/24h. This unit shows the amount of moisture that can be moved from inside to outside, per square metre, over a period of twenty-four hours. The higher the number, the more moisture the jacket can let out.

5 000–10 000 g/m²/24h: everday walks

10 000–15 000 g/m²/24h: hiking and biking

>15 000 g/m²/24h: running and ski touring

Taped seams

When a jacket is sewn together, the needle punctures the fabric, creating small holes. To make sure the seam is waterproof, tape is applied over the stitches to help keep the rain out. These seams are usually on the inside of the jacket, and the tape is attached to them using glue or by melting it with heat. Heat and high pressure can also be used to attach the parts of the jacket to each other. This results in a jacket that’s completely seamless, which helps keep out both rain and dirt.

Ventilation zips

These ’pit zips’ are your best friends when your heart rate increases! If a jacket’s fabric is less breathable, there are often zipped openings at the armpits. Sometimes you can open these areas at both ends thanks to a two-way zippers. This is a great way of letting out any extra body heat without having to take off your jacket.

Denier

The term ’denier’ (D) describes the thickness of the threads or fibres that make up a material. A higher number means thicker thread and a more durable jacket. For hiking, for example, you should choose a jacket with a denier number between 30 and 80. Fun fact: all fibres with less than 1D are called microfibres.

Membrane

If you were to zoom in on your jacket with a microscope, you’d see a membrane with tiny pores. These are large enough to allow moisture from your body to pass through, but small enough to keep out snow and rain. It’s a smart feature that allows the coat to breathe without your body getting wet from the inside or outside. The most famous membrane is GORE-TEX, but also keep your eyes open for Dermizax, Event and HProof (from Haglöfs).

Layers

’But I can only see one layer of material’ That’s true, but what’s happened is that several layers have been laminated together to make one piece of fabric. How many different layers your jacket has depends on how the membrane in the material has been protected.

Water columns

To figure out how much rain and snow a jacket can withstand, the fabric’s ’water column’ can be measured. A water column is how much water pressure fabric can take before it lets water through. Water columns are measured in millimetres and the higher the number, the better the protection.

2 layers – An outer layer of material where the membrane is laminated on the inside, along with a loose, protective mesh lining. This kind of material is available on everyday jackets and is often cheaper.

2,5 layers – Instead of a loose mesh lining, the membrane is protected by a treated surface on the inside. These jackets are easy to pack, so they’re perfect for day trips when there’s a risk of rain.

3 layers – A thicker and more durable jacket that has an inner layer to protect the membrane. All three layers are laminated together, which makes the jacket more durable, making it ready to be worn under a backpack or climbing harness. <10,000 mm: drizzle and light snow

10,000 - 15,000 mm: light rain and light snow

15,000 - 20,000 mm: moderate rain and moderate snow

>20,000 mm: heavy rain and heavy snow

Washing 101

’You shouldn’t put your shell jacket in the washing machine because it’ll damage the membrane’. This is probably something we’ve all heard, but it’s not true at all! Over time, dirt and sweat clog up the membrane’s pores, which impairs its ability to keep water out and release moisture and heat.

1. Close all zips and Velcro fastenings 2. Turn the jacket inside out 3. Follow the instructions on the care label (even the small print!) 4. Invest in detergents that are made specifically for shell jackets 5. Note! Avoid products containing fabric softener, stain remover or bleach 6. Need impregnation? Some detergents have a clever 2-in-1 combo! 7. Protect the membrane and choose a more gentle washing program 8. Tips! Add an extra rinse to remove all the detergent 9. To give the water protection a head start, it’s best to dry the jacket in a dryer on low heat 10. You can also use an iron or hair dryer (even on low heat), just make sure to put a piece of fabric in between the iron

or hair dryer and the jacket