Glossary

A waterproof garment is one that should reliably keep out water even in prolonged rainfall. There are certain standards for this. In the UK, manufacturers can only claim a fabric is waterproof if the Hydrostatic Head is equal to or more than 1500mm. Most waterproof jackets designed for outdoor sports tend to have a much higher Hydrostatic Head than 1500mm. For example, all GORE-TEX Products have a minimum of 28,000 mm Hydrostatic Head.

Water resistant fabrics can partially resist water penetration, but don’t provide complete protection. Water resistant products are intended to endure light water contact, like light showers or short snow flurries, but they are not capable of withstanding prolonged exposure to wet weather.

Hydrostatic Head (HH) is a way of measuring how waterproof a fabric is. The resulting measurement in millimetres relates to how high a column of water standing on the fabric would need to be before the water would penetrate the fabric. All GORE-TEX Products have a minimum of 28,000 mm Hydrostatic Heads.

A breathable waterproof is one designed to allow moisture vapour, such as sweat, to pass through it from the inside of a garment to the outside, while also preventing water from getting in. Waterproof jackets tread a delicate balance between waterproofness and breathability. If your jacket is not breathable, you may end up getting cold and wet from your own sweat. Some jackets will include pit zips to allow heat and moisture to escape, while others rely on partially permeable membranes, and the heat produced from your own body in a fully zipped up jacket, to push moisture out.

The separation of laminated layers, such as the waterproof membrane and the outer or inner fabric, often due to age, heat, contamination, or mechanical damage. This process can make a garment lose its waterproof qualities and may appear as flaking, bubbling, or wrinkling of the material.

This term describes when water is no longer beading and running off the surface but instead is being absorbed into the garment's outer layer of fabric. The fabric can appear darker in places where wetting out has occurred. It is usually most noticeable in high-wear areas such as the shoulders or under rucksack straps, or where the jacket has come into contact with oily substances such as suncream. Washing and drying your jacket correctly will restore the DWR's effectiveness and prevent wetting out.

The thickness and fluffiness of the insulation material. The loft creates tiny pockets of trapped air that provide warmth by preventing heat from escaping your body. The more loft an insulation has, the more air it can trap and the warmer the garment will be.

"Fill power is the best way to determine the quality of down in a product, with a bigger number meaning higher quality down. Higher fill power tends to correlate with larger down clusters, which make for loftier, fluffier-feeling products. However, fill weight – how much down is in your jacket – not fill power is the biggest factor in determining how warm a product is overall. Fill power is more about how much each gram of down contributes to overall warmth, with higher numbers making for a higher warmth-to-weight ratio." - Dr Matt Fuller, Innovation Manager, Product and Process Engineer, Mountain Equipment

Certifications for down-insulated clothing that provide traceability and promote the humane treatment and welfare of ducks and geese used for down and feathers. Both standards provide a traceability system for the down in finished products.

Down that has been treated with a durable water-repellent (DWR) coating, making it resistant to moisture and retaining its insulating warmth and loft in damp conditions.

The German Institute for Standardisation. It is a measurement scale that determines when your bindings will release and cause you to fall out of your skis.

The flex value of a ski boot describes its stiffness. In general, the flex index is between 60 and 140: The lower the flex, the softer the ski boot; the higher, the harder. Higher flex values are mainly found in ski racing boots.

A sliding or fixed low-friction device under the toe piece of ski bindings, designed to minimise friction and ensure smooth release during a fall.

Made for extreme conditions and the most demanding activities.

Deliver solid protection and are made for demanding activities.

These use an ePE membrane, recycled and/or solution dyed textiles and PFA-Free* DWR

A method used in creating waterproof clothing. Bonded seams join fabric layers using either an adhesive tape and heat and pressure to create a stitch-free seam or a fabric strip to encase and finish the raw edges of a stitched seam.

A unit of measurement to describe the thickness of the fibres or yarns used in a fabric. In waterproof clothing, a 30D fabric might be used in a light waterproof, designed for packing away or fast hiking, for example, while 80D fabric might be used in waterproofs designed for winter climbing. Some jackets used a combination of Deniers, using a thicker fabric for high-wear areas around the shoulders and knees, for example.

Taped seams cover the holes created by stitching, so no water can leak through them. All GORE-TEX Garments use GORE Seam Tape.

A stitch used to reinforce areas of high wear or stress on clothing. A pocket opening, the bottom of a zip fly, or the top and bottom of belt loops are places where you might find bar tacks.

DWRs, or Durable Water Repellents, are the chemicals applied to the outside of the garment to help water bead and run off the fabric. For a long time, these DWRs used a chemical class called fluorocarbons, but after research showed some fluorocarbons to be persistent pollutants, their use has been banned.

Also sometimes written as ‘PFC-free’ or ‘PFAS-free’ DWRs. These new DWRs use different chemistry to achieve a similar result to traditional DWRs, but there are some key changes. For outdoor users, the biggest change they may notice is that their new jacket needs washing and drying more regularly to remain functional. This is due to PFC-free DWRs being less oleophobic than traditional DWRs. This means that oily substances such as suncream or oils from your skin and hair, can temporarily reduce the performance of the DWR and lead to wetting out. Washing and drying your jacket regularly can prevent this. See our care pages for details on how to care for your jacket.

Fluorocarbons are a class of chemical compounds with carbon-fluorine bonds. Fluorocarbons have been used in consumer products around the world since about the 1950s, not just in waterproof clothing, but in non-stick pans and stain-resistant carpets, for example. You may also see similar terms such as PFAS, or Perfluorocarbons (PFCs). These terms refer to a broad group of compounds with many differing physical attributes and properties. When you see Fluorocarbons, PFCs or PFAS discussed in relation to waterproof garments or pollution, this generally refers to a group of PFCs that have been identified to be of environmental concern.

These stand for Polytetrafluoroethylene and expanded Polytetrafluoroethylene. PTFE is a polymer with non-stick properties is the basis of the original GORE-TEX Membrane. Next Gen GORE-TEX Products use a different membrane chemistry. Crucially, PTFE polymers do not degrade to become PFC of environmental concern.