There is a simple test for Harris Tweed. Take a piece of the cloth and push a pencil through it. The yarns give way to let the pencil pass – and then, when you remove it, they settle back. The cloth es behind the pencil as if it was never there. The yarns do not break. They simply accommodate, and return.
This is not a party trick. It is a demonstration of what happens when a cloth is made correctly, from the right material, without chemical interference. And it tells you something important about why Harris Tweed performs the way it does in wet weather.
THE LANOLIN QUESTION
Harris Tweed is arguably the most waterproof natural and untreated cloth available. That claim rests on something specific: the Harris Tweed Act of 1993 – the only piece of legislation in the world that protects a cloth – restricts the use of chemicals in Harris Tweed’s production. Most commercial textile processing strips the natural oils from wool to make it easier to dye and treat. Harris Tweed is not processed that way.
The result is a cloth that retains a far greater concentration of lanolin – the natural, waxy oil found in sheep’s wool that evolved, over millennia, precisely to shed water. Lanolin is not added to Harris Tweed. It is simply not removed.
HOW IT WORKS IN PRACTICE
Harris Tweed is heavier than most tweeds – typically 470 to 500 grammes per running metre, with specialist shooting cloths for gamekeepers running to 700 grammes. The combination of weight and lanolin creates a cloth with specific weather behaviour: when rain hits those large, oily threads, they expand slightly to close any gaps and keep moisture out. When the cloth dries, the threads contract and allow air to pass through, so the cloth breathes.
This is passive, structural waterproofing – no coating, no membrane, no treatment that washes out after a season. The performance is in the cloth itself, not applied to its surface.
THE REAL-WORLD COMPARISON
Anyone who has spent time outdoors in Harris Tweed in genuinely wet conditions will tell you the same thing. It does not perform like a wax jacket – which is heavier, less breathable, and degrades without reproofing. It does not perform like modern technical shooting clothing, which achieves similar waterproofing but at a significant environmental cost in production. Harris Tweed performs like what it is: a cloth that evolved over centuries in one of the wettest places in Northern Europe, worn by people who worked outside and could not afford to be wet.
The Outer Hebrides, where every piece of Harris Tweed is still handwoven under the terms of the 1993 Act, sit on the far north-western edge of Europe. The weather that arrives there from the Atlantic is unforgiving. The cloth the islanders wove – and still weave, on treadle-driven looms in their own homes, without electricity – was built for that reality. It was not designed in a laboratory. It was refined by use.
WHY IT STILL MATTERS
The practical waterproofing of Harris Tweed is not an argument against modern technical clothing. It is an argument for understanding what natural materials, produced correctly, can genuinely do – and for recognising that the Harris Tweed Act of 1993 has preserved a cloth performance that would otherwise have been engineered away in pursuit of lower production costs and lighter weights.
At Walker Slater, our Harris Tweed jackets and coats are cut to be worn as the cloth was intended – outside, in the kind of weather Scotland reliably provides. The cloth arrives from the mills of Stornoway with its lanolin intact and its properties unchanged. What you wear is what the Hebridean weavers made.
Discover ourHarris Tweed coats and jackets at Walker Slater.
