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Written by George Fisher


No, not a film starring Kenneth Williams and Hattie Jacques, but a strategy to get the most from your waterproof and breathable clothing.

When talking to people about outerwear, the two key features everyone mentions are waterproof performance and breathability; both fundamental aspects for any outdoor protective shell wouldn’t you think? The thing is, few people appreciate what these features are and, more critically, how they are inter-dependent.

Waterproofness? Easy - a fabric that keeps water out! Most plastics will do that; a PVC shell would keep everything out, but it would also keep everything in. This is where breathability comes into play. Breathability is a key feature in our range of waterproofs, and the most misunderstood!

‘Breathability’ describes a fabric’s ability to transfer moisture vapour from the inside of a garment to the outside. This helps maintain comfort. During exercise we warm up, our body perspires and the energy used to evaporate this sweat cools our skin. BREATHABLE FABRICS DO NOT STOP YOU SWEATING! Perspiration is a natural function of being alive; breathable fabrics help manage one of the unwanted side effects of sweating, that of moisture build up within our clothing layers.

Breathable waterproof fabrics contain a barrier within their construction that is impermeable to water in its liquid form, but which allows moisture vapour to migrate from areas of high humidity to lower humidity (usually inside to out). Gore-Tex, the best-known waterproof breathable fabric, uses an expanded PTFE* membrane that contains 9 billion micropores to the square inch. These pores are 1/20,000th the size of a water droplet, making it impenetrable to liquid water but still large enough to allow water vapour molecules to pass.

As well as an impermeable barrier, all waterproof breathable fabrics have an outer surface treated with a DWR (Durable Water Repellent). The DWR is a chemical, which reduces the surface tension of liquid water, encouraging it to bead up and roll off rather than soak in. This allows fabric to shift water vapour most efficiently; an outer fabric that is soaked (wetted out) impairs the movement of moisture vapour and leads to increased condensation inside… basically you’ll get damp!

You can help your waterproof continue to perform by adding a little TLC – regular washing, reproofing and tumble-drying.

Rather than standard washing powders or liquids, use Granger’s Performance Wash to clean your garment – this removes dirt without stripping off the existing DWR. Once clean, reproof your garment either by putting it through another wash cycle with Granger’s Clothing Repel, or spraying with Granger’s Xtreme Repel. Then, to fix the water repellent treatment to the fabric, tumble dry at a low heat.

Those of you who already use Granger’s products will note that the names of the re-proofers have changed. Granger’s is now using a completely new technology for DWR. For many years virtually all treatments were based on Perfluorooctanoic Acid (PFOA), also known as C8, until it was discovered that PFOA doesn’t degrade and persists in the natural environment. The C8 chemicals were therefore replaced by shorter-chain polymers known as C6s; these are PFOA free and have become the norm across the waterproof fabric market.

In line with the market, Granger’s swapped from C8 to C6 technology and, like all other manufacturers, they found that the new technology wasn’t as effective. Rather than accept this new lower standard, Granger’s began experimenting with different formulations, looking to maintain the environmental improvement of C6 and also improve on performance. Years of research have now delivered APT (Acrylic Polymer Technology), a blend of fluorocarbon-free polymers that provide a highly breathable DWR.

As things stand there’s nothing available that will perform to the DWR standard of old C8-based reproofers. Environmental concerns mean we can’t return to the old technology, so Granger’s has come up with the best possible option. The implication for everyone who owns and uses waterproof clothing is that they need to wash and reproof their garments more regularly, in order to maintain performance.

Get into the habit of washing, reproofing and tumble-drying your waterproofs often. Not only will you remain more comfortable for longer, you will also extend the life of your garment. Well-maintained clothing functions better and lasts longer… keeping it out of landfill for longer.

* That’s PolyTetraFluoroEthylene, a synthetic fluoropolymer… Ed)

Cover photo by Stuart Holmes