ISO 20200 is one of the most requested tests we run, and one of the most misunderstood. People often assume a pass means “compostable”. It does not, and understanding why makes the result far more useful.
The set-up
The test simulates an industrial composting environment at laboratory scale. Your material is mixed into a synthetic compost: a defined blend of ingredients such as sawdust, rabbit food, compost inoculum, starch, sugar, oil and urea. The recipe is standardised so that results can be compared between materials and between laboratories.
The mixture is held in containers and incubated at a controlled, elevated temperature, kept aerated and kept moist. Over a period of at least three months the samples are monitored and then examined.
What is measured
The question being asked is a physical one: how much of the material is still there in pieces large enough to be recognised? At the end, the compost is sieved and the fragments left behind are compared with what you started with. Less residue means a higher degree of disintegration.
What a good result means
A good result tells you that, under industrial composting conditions, your material breaks up and does not persist as visible fragments. That is valuable. It is a requirement of any compostability certification, and it tells you whether your material is likely to cause problems in a composting facility.
What it does not tell you
- **That microbes have consumed it.** Fragmenting is not the same as biodegrading. That is a different question, answered by measuring carbon dioxide (see ISO 20136).
- **That the compost is safe.** A material can break up beautifully and release metals or other chemicals of concern. That is what EcoTox tests are for.
- **That plants will grow in it.** Plant response testing covers this.
- **That it will break down at home.** Industrial conditions are much hotter than a garden bin.
Where it fits
For many customers ISO 20200 is the second step, after a Quick Screen has shown that a material is a promising candidate. It is the point at which you start to build a case that can be shown to a buyer or a certifier.
If you are weighing up where to begin, tell us about your material and we will suggest a sensible sequence of tests.
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