What happens to merino wool at the end of its life?

It's a question worth asking, and we put a lot of thought into the materials we use at Isobaa. Why merino? Why natural fibres? Why quality over quantity? But the conversation about sustainability doesn't end at the point of purchase. What actually happens to a merino garment when it's worn out, outgrown, or simply past its best?

The answer, for the most part, is a good one.

Merino is a natural protein fibre

Wool is made of keratin, the same protein found in human hair. In the right conditions (soil, compost, moisture), it breaks down naturally, returning nitrogen, sulphur, and carbon back to the earth. A merino garment left to compost will typically biodegrade within a matter of months to a few years, depending on conditions. Compare that to a polyester fleece, which can persist in the environment for decades, shedding microplastics throughout its lifetime and long after.

This is one of the most important distinctions between natural and synthetic fibres, and one that often gets lost in broader conversations about sustainable fashion.

A note on superwash treatment

We want to be transparent here, and in this case, transparency comes with some good news. Our merino is treated using EXP Superwashing, a process developed specifically to eliminate the chemicals used in conventional superwash treatments. Where the traditional approach relies on chlorine and Hercosett resin, EXP uses natural salts as the oxidising agent. No chlorine. No plastic-based resin coating.

It's a meaningfully better process, and one we're glad to be using.

The broader question of how superwash treatments affect end-of-life biodegradation is still being studied across the industry, and we'll keep following that conversation. What we can say with confidence is that merino remains a natural protein fibre at its core, and will still biodegrade in a way that wholly synthetic fabrics simply won't.

The best thing you can do: make it last

Before end-of-life comes longevity. Merino is remarkably durable when cared for properly. It resists odour, regulates temperature, and holds its shape far longer than most fabrics. Washing less frequently, following care instructions, and storing it well will extend the life of a garment significantly. A base layer worn for ten years has a fraction of the environmental footprint of one replaced every two.

If something develops a small hole or a worn patch, it's worth repairing. Merino darns well, and a small amount of effort can add years to a garment's life. We'd always rather you repair than replace.

When a garment really is done

When a piece genuinely reaches the end of its useful life, there are a few good options.

If it's still wearable, donation or resale extends its life for someone else. Platforms for second-hand outdoor and activewear have grown significantly, and a well-made merino piece has real value on the secondhand market.

If it's beyond wear, wool recycling is increasingly accessible. A number of textile take-back schemes now accept natural fibre garments, breaking them down into new yarn or insulation material. It's worth checking whether your local council or a specialist recycling programme accepts wool. More do than you might expect.

For garments that are truly at the end (frayed, felted, or otherwise unusable), composting is a genuine option. Cut or shred the fabric, add it to a compost heap alongside other organic matter, and it will break down over time. It's a fitting end for a natural fibre: returning to the earth it ultimately came from.

Why this matters to us

At Isobaa, we make garments designed to last. But we also think honestly about the full lifecycle of what we produce, including the parts that are complicated. Merino isn't perfect, and neither are we. What we can commit to is using the best materials available, being transparent about their limitations, and continuing to ask the right questions as the industry evolves.

A garment that biodegrades, lasts longer, and can be repaired is still, by most measures, a better choice. We think that's worth standing behind.