Walk down any shopping aisle and you will find the words biodegradable and compostable used as if they meant the same thing. They do not, and the gap between them is where most greenwashing lives.
Biodegradable
A material is biodegradable if microorganisms can break it down and turn its carbon into carbon dioxide, water, biomass and, in the absence of oxygen, methane. That is all. The word says nothing about how long this takes, or under what conditions. A leather shoe in a landfill is technically biodegradable, if you are prepared to wait long enough. On its own, the claim is close to meaningless.
Disintegrable
Disintegration is the physical breakdown of a material into small pieces. It is easy to see, which makes it easy to over-trust. A material can fall apart into fragments that are then invisible to the eye and still be there, unchanged, in the soil. Disintegration is a necessary step but it is not proof that anything has been consumed.
Compostable
Compostable is the strict one. A compostable material has to do several things at once, within a defined time and under defined conditions:
- disintegrate, so it is not recognisable in the finished compost
- biodegrade, with a measured proportion of its carbon converted to CO₂
- contain no more than set limits of heavy metals and other substances of concern
- leave compost that does not harm plants or soil organisms
Different standards set these thresholds for industrial composting (high temperature, managed facilities) and for home composting (lower, variable temperatures). A claim of “compostable” should always say which one it means.
Why the order matters
Think of it as a ladder. Disintegration is the first rung, biodegradation the second, and a clean, plant-safe compost the third. A material can stand on the first rung and be nowhere near the top. This is exactly why our testing is split into separate pathways: ISO 20200 looks at disintegration, ISO 20136 at microbial consumption, EcoTox at what is left behind, and plant response testing at whether the result can grow something.
What to ask a supplier
- Which standard was the claim tested against?
- Industrial or home composting?
- Was it the whole product, including dyes, finishes, threads and adhesives, or only the main material?
- Can I see the test report?
If the answer to the first question is “it just is”, treat the claim with caution.
If you are not sure which claim your material could honestly support, get in touch and we will point you to the right starting test.
By Authenticae. Back to the blog