How Does Waterproof Fabric Work and What is System Dual Protection?

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How Does Waterproof Fabric Work and What is System Dual Protection?

By Keela

Published on March 25, 2026

3 min read

Understanding Waterproof Fabric Technology: How System Dual Protection Manages Moisture

For many in the outdoor community, reliable kit isn’t just about comfort – it’s about safety, confidence, and the ability to keep moving when the weather turns. From demanding mountain summits to harsh Arctic environments, Keela’s System Dual Protection (SDP) has earned a strong reputation among adventurers, emergency services, and mountain rescue teams alike.

Recognised for its innovation, Keela was honoured with the Queen’s Award for Enterprise: Innovation – one of the UK’s most prestigious business awards – celebrating outstanding achievements in innovation, international trade, and sustainable development. The award reflects Keela’s continued commitment to designing performance clothing that works in real-world conditions, not just laboratory tests.

But before we dive into how SDP works, let’s talk about something every walker and outdoor enthusiast has experienced…

Ever Felt Wet Inside Your Waterproof Clothing?

You finish a climb or a brisk walk and notice moisture inside your jacket. It’s a common frustration – and the immediate thought is usually, “My waterproof is leaking.”

In most cases, it isn’t.

The moisture you’re feeling is often condensation, not rain penetration.

Think about your car windscreen on a cold day. The difference between warm air inside and cold air outside causes moisture to form on the glass. Your body creates a similar environment inside a waterproof jacket when you’re working hard outdoors.

Even the most advanced waterproof garments can struggle to “breathe” effectively in cold, wet UK conditions. Many breathability claims are based on international test standards carried out in dry environments at temperatures above 21°C – conditions that rarely reflect the realities of a windswept ridge or a rainy winter walk.

So What Is System Dual Protection?

Keela’s award-winning System Dual Protection (SDP) was developed to tackle the real issue: managing internal condensation during wet and cold conditions.

Instead of relying solely on traditional breathability claims, SDP uses a practical two-layer approach:

A tough, durable 100% waterproof outer layer that shields you from wind, rain, and abrasion.

A lightweight inner layer with a hydrophilic (water-loving) membrane designed to move sweat and condensation away from your body quickly.

Between these layers sits an air gap, which helps regulate body temperature by retaining warmth when you’re inactive and reducing the chilling effect caused by damp clothing.

Built for Real-World Conditions

System Dual Protection has been adopted by emergency services and mountain rescue teams who operate in challenging, unpredictable environments. It has also become a trusted choice among walkers, climbers, and outdoor enthusiasts who need dependable performance on everything from local trails to remote expeditions.

OS champion Ciss Silver is out on the trail in her Stratus Jacket, featuring @keelaoutdoors award-winning System Dual Protection (SDP) and a secure, concealed OS map pocket.

Because at the end of the day, staying dry isn’t just about a waterproof rating, it’s about managing the reality of movement, weather, and changing conditions in the outdoors.

Confidence When You Step Outside

As outdoor explorers, we know that the weather rarely behaves as planned. Understanding how moisture builds up – and choosing clothing designed to manage it – can make the difference between a comfortable day out and a miserable one.

Through continued innovation and development of System Dual Protection, Keela aims to ensure that wherever your next OS-mapped adventure takes you, you can face the elements with confidence and comfort.

Find out more at www.keelaoutdoors.com

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By Keela

Keela is an award-winning Scottish outdoor performance clothing brand with a commitment to sustainability. Find out more at www.keelaoutdoors.com