Bio-based wallcoverings, and what the percentage means

Bio-based is not a property. It is a percentage. A specification that asks for bio-based without asking for the number has not really asked for anything.

The number comes from a carbon test. ASTM D6866 measures the ratio of new organic carbon to total organic carbon in a material, using radiocarbon analysis. Carbon that came out of a plant a few years ago is measurably different from carbon that came out of the ground a few million years ago, and the test separates the two. The result is a percentage of bio-based content. Where that percentage is certified under the USDA BioPreferred program it has been verified by a third party rather than asserted by the maker.

The percentage varies more than the word suggests. A material can be a tenth bio-based or nine tenths bio-based and both are accurately described as bio-based, so two wallcoverings carrying the same label can be a long way apart in substance. The number is the specification. The description is not.

There are two routes into a bio-based wallcovering and they produce different materials. One replaces the fossil feedstock inside a synthetic: sugarcane is fermented to ethanol, the ethanol becomes polyethylene, and the polyethylene is drawn into a fibre and woven. The cloth behaves like a synthetic because it is one, with the carbon sourced from a plant instead of a well. The other starts from cellulose, making the substrate itself from wood taken from forested sources.

What bio-based content does not tell you is how the material performs, whether it can be recycled, or what happens to it at end of life. Those are separate questions with separate evidence, and a high percentage answers none of them.

The ranges below are the bio-based wallcoverings in the portfolio. The percentage and the certificate are available for each.