Ever noticed that a polyester T-shirt is smellier than a cotton one after you work out? New University of Alberta research now shows why.
Analysis of various fibres soaked in a solution of simulated sweat showed that cotton and viscose, which are cellulosic, or plant-derived fibres, absorbed — and consequently released — smaller amounts of odour-causing compounds than polyester, nylon and wool.
The key finding from the study explains why some commonly worn fibres are smellier than others when people sweat, says Rachel McQueen, a clothing and textiles scientist in the Faculty of Agricultural, Life & Environmental Sciences who conducted the research with colleagues from the University of Otago in New Zealand.
"Although we know that polyester is smellier after being worn next to sweaty armpits compared to cotton T-shirts, we haven't really known why. Now we have a better understanding of how odorants transfer and are selectively absorbed by various fibre types in sweat."
The study's method of using simulated liquid sweat also offers an important fresh approach to exploring the issue, she notes.
"Body odours commonly transfer to clothing through liquid sweat, but investigation of odour retention in textiles often neglects this route of exposure in test procedures," McQueen says, noting that standard scientific methods include examining only how the odour passes through the air to the textile. "If you had a sweaty armpit that never actually touched the shirt you're wearing, then the fabric wouldn't get very smelly.
"By studying the transfer of odorants to fabrics using a liquid sweat solution, we were able to give a more realistic insight into how these smell compounds really get into our clothes."
In the study, the researchers soaked the fibres in the sweat solution for different periods of time, then examined the release of various odour-causing compounds from those fibres using analytical equipment that can detect odorants in the air in real time — more like the human nose does.
Overall, the study showed that the cellulosic fibres took in lesser amounts of the compounds when transferred through the sweat solution than textiles made of wool, nylon and polyester fibres, which conversely, initially released higher amounts of the smelly compounds.
