How Fast Does Silk Biodegrade?
70% in Just 6 Months

You've probably never thought about this question. But I came across a study recently that I found genuinely interesting.

In July 2026, a research team from Nanjing Agricultural University published a paper in the journal Science of the Total Environment. They did something that not many people have done before: they buried silk in soil and watched how long it took to disappear.

The results were striking.

Six Months – and 70% of the Silk Was Gone

The data showed that after six months in soil, silk had degraded by 70–90%, depending on the sample. In other words, within half a year, most of a piece of silk fabric is effectively "eaten" by the soil.

That's significantly faster than many people assume. For context: cotton degrades in 1–5 months, wool in 1–5 years, and hemp in about 1–3 months. Silk falls on the faster end of the natural fibre spectrum.

By contrast, synthetics are measured in centuries. A polyester garment buried in soil can take 200 years to break down – and as it does, it releases microplastics into the environment. The contrast could not be more stark.

Silk Degradation Is Actually "Fertilising" the Soil

What makes the findings even more interesting is what happens during degradation. The research team detected sericin protein residues in the soil at multiple test sites.

What does that mean? As silk degrades, it actually releases nutrients into the soil.

Silk is made primarily of two proteins: fibroin and sericin. As these proteins break down, they turn into amino acids, nitrogen, and organic carbon – compounds that soil microorganisms and plants can use. A piece of silk fabric doesn't just "disappear" – it transforms, becoming part of the soil ecosystem.

Synthetic degradation is completely different. Polyester breaks down into smaller polymer fragments, releasing additives and microplastics that offer no nutritional value to the soil – and often cause harm.

Why Does This Matter?

Most people buy silk because it feels good, drapes well, and looks beautiful. Few think about what happens to it at the end of its life.

But that question is becoming increasingly important.

Microplastic pollution has become one of the defining environmental issues of the decade. Synthetic fibres shed during washing have entered the oceans, the soil, and even human bodies. The EU is already moving towards regulations on microplastic emissions from textiles.

In this context, the biodegradability of natural fibres is shifting from a niche concern to a competitive advantage.

I'm not suggesting silk will replace synthetics – global silk production is around 70,000 tonnes per year, a tiny fraction of the synthetic fibre market. But if you're a silk brand, this is something your customers are increasingly likely to care about.

They want to know that the garment they buy won't become a burden on the planet for centuries. With silk, the answer is clear: it won't. And in the process of returning to the earth, it feeds it.

What Can You Do With This Information?

If you're a brand, here's where this data can be useful:

• Product descriptions. When you're talking about sustainability, biodegradability is a concrete, data-backed argument. "Our silk returns to the earth within months" is more compelling than a vague "natural fibre" claim.
• Marketing content. A soil degradation test is visual and evocative. If you have access to lab conditions, consider running your own burial test and documenting it at intervals – it's powerful content.
• Customer reassurance. When customers question silk's environmental credentials, you can point to the numbers: 70–90% degradation in six months, compared to 200 years for polyester.

Back to Nanchong

The silk we trade here in Nanchong doesn't end its life in a customer's wardrobe. It ends somewhere else. And if one day that piece of fabric is discarded, it won't linger in the ground for centuries like plastic.

There's something reassuring about that.

I find. I check. I seal. You relax.