Most fleece and midlayers sold today - including ones marketed as 'recycled' or 'sustainable' - are made from polyester, a plastic that sheds microscopic fibres every time it's washed or worn. Those fibres have been found in human blood, lungs, and placental tissue. And the air in our homes and cars carries even more of them than the air outside. Woolf was founded because we think people who love the outdoors and nature would prefer something that performs beautifully without trashing our health and the planet. PureFleece® is 100% Merino lambswool, precision woven at a specialist mill - with zero plastic, zero polyester, zero compromise.
The scale of the problem
Textiles are the fourth largest source of microplastic pollution in Europe, behind only paint, tyres, and plastic pellets. A single gram of synthetic fleece fabric - about the weight of a paperclip - can shed as many as 3.7 million plastic fibres. Up to 70% of a synthetic garment's lifetime shedding happens in its first five washes, meaning the newer the fleece, the worse the problem, not the better. Those fibres don't just disappear once they're in the wastewater - they work their way into rivers, soil, and the ocean food chain, a journey we cover in more depth in Microplastics in the ocean - the hidden crisis.
Related reading: Is 'recycled' polyester actually more sustainable than virgin polyester?
The recycling myth
Buying 'recycled' polyester feels like the responsible choice. However recent testing across 51 garments from major brands found recycled polyester actually sheds around 55% more microplastic fibres than virgin polyester - and the fibres it sheds are finer, meaning they travel further and stay airborne for longer. Recycling doesn't remove the core problem. It's still plastic, and plastic still sheds, just even more.
What we breathe
Shedding isn't limited to the washing machine. Synthetic clothing and textiles are the single biggest source of the microplastic fibres found in indoor air - and indoor air carries two to five times more of them than the air outside. A peer-reviewed lung study found that inhaled textile microfibres, including nylon, actively impair the airway's ability to repair itself.
Related reading: Do you breathe in microplastics from your own fleece?
Merino wool: the alternative that already exists
None of this is a new problem to solve - it's an old material we walked away from. Merino wool has clothed people through genuinely hostile weather for centuries, long before polyester fleece existed at all (the first Polartec fleece dates to 1981). At 20 microns, Merino fibre is fine enough to wear directly against skin without the itch associated with coarser wool - regular wool sits at around 35 microns. It absorbs up to 35% of its own weight in moisture while still feeling dry, and it's naturally warmer than synthetic fleece for the same weight. And its it naturally breathable, so you're not left overheated or cold and clammy in your own sweat. We go into the performance case in full in The new performance standard: why wool wins.
Related reading: Merino wool vs synthetic fleece: what's actually warmer? · Is Merino wool itchy? The 20-micron difference explained
Our answer: PureFleece®
PureFleece® fabric is created exclusively at one of the world's finest mills, in Yorkshire, then made into garments in Britain. It's woven, not knitted - a slower, more precise process that gives the Merino Wool more loft, more durability, and a better drape than knitted alternatives. It carries Official Woolmark Certification, uses Oeko-Tex certified dyes, and comes from mulesing-free Merino. There is no Superwash finish (the plastic polymer coating most merino brands apply to make garments machine-washable), and no synthetic fibres anywhere in the garment - not even the thread or the zips. The full story of that supply chain is in Where PureFleece® actually comes from.
Related reading: Woven vs knitted: why it matters for durability and warmth · What Woolmark certification actually means · Mulesing-free Merino: what it means and why we insist on it
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Sources: The Pew Charitable Trusts (2026); Changing Markets Foundation / Microplastic Research Group, Çukurova University; American Journal of Respiratory and Critical Care Medicine.