Adsorption of odour molecules
Smell molecules stick to surfaces rather than dissolving into them. It explains why two shirts worn identically smell differently — and it does not, yet, explain the open tub of bicarbonate.
In detail
An odour is a molecule small and light enough to leave a surface and reach a nose. Adsorption is what happens when one sticks to a solid surface instead: it is held at the boundary rather than dissolved into the bulk, and while it is held, it is not being smelled. THE EVIDENCE HERE IS ABOUT FABRIC, and it is direct. Shirts worn for the same intense session and then incubated smelled significantly less pleasant and more intense in polyester than in cotton, across every quality a trained panel assessed. Part of that is microbial. Part is physical, and the paper says so: cotton, being largely cellulose, has a high adsorbing capacity and HOLDS volatile odour molecules, while polyester adsorbs them poorly and therefore RELEASES more. The counter-intuitive consequence is that the fibre which holds odour smells less. WHAT THE EVIDENCE DOES NOT COVER: how much odour an open dish of bicarbonate, charcoal or coffee grounds takes out of a fridge or a car. That question has no answer, because no authoritative source addresses adsorption as a general surface phenomenon — the evidence runs to fibre only.
Why
- Cotton is explained by Adsorption of odour molecules
Why the fibre that holds odour is the one that smells less.
- Polyester is explained by Adsorption of odour molecules
The other half of the same finding: poor adsorption means more released.
- Fabric conditioner is explained by Adsorption of odour molecules
- Milk stain is explained by Adsorption of odour molecules
- Tobacco residue is explained by Adsorption of odour molecules
- Faeces is explained by Adsorption of odour molecules
- Fragrance is explained by Adsorption of odour molecules
- Urine is explained by Adsorption of odour molecules
Sources for this page
Sources
Microbial Odor Profile of Polyester and Cotton Clothes after a Fitness Session
Applied and Environmental Microbiology, American Society for Microbiology, 2014 · Scientific literature
Relied on for: That cotton, being largely cellulose, has a high adsorbing capacity and holds volatile odour molecules, whereas polyester adsorbs them poorly and so releases more of them, and that polyester shirts smelled significantly less pleasant and more intense than cotton after the same session. (states this directly)