Many people suffer from the unpleasant smell emitted by polyester shirts, which lasts longer than the smells produced by cotton shirts.
Thanks to some research from the University of Alberta, we now have an interesting answer to this mystery.
Rachel McQueen, a senior textile scientist from the School of Agricultural, Life and Environmental Sciences, in partnership with her peers from the University of Otago in New Zealand, led the study to uncover the secrets behind why some textiles produce more unpleasant odor than others when we sweat.
The team analyzed how different fibers, cotton and viscose (both plant-derived and cellulosic fibers), along with polyester, nylon and wool, reacted to a solution that mimics sweat, which can be produced by exercise.
The results found that cotton and viscose absorb some of the odor-causing compounds, resulting in less odor release than their polyester, nylon and wool counterparts.
“We now have a better understanding of how odors are selectively transported and absorbed by different types of fibers in sweat,” Rachel explains.
This study, which uses a method of simulating liquid sweat rather than simply examining how odor passes through the air, essentially paints a clearer and more realistic picture of odor transmission.
The Science Behind Polyester and Cotton
Sweat is mostly water, but it also contains oily compounds that bacteria convert into odors. These compounds can react differently with different textiles, depending on the composition of their fibers.
For example, hydrophilic fibers like cotton and viscose absorb more sweat water, while polyester absorbs more water-insoluble odors, along with those potentially odorous oily compounds.
This explains why clothes made of cellulose fibres, such as cotton, viscose and possibly bamboo, become less smelly than synthetic clothes after wearing them for a while.
“Body odors are typically transferred to clothing through liquid sweat, but investigations of odor retention in textiles often neglect this route of exposure in testing procedures,” says Rachel.
By studying the transfer of odors to fabrics using a solution of liquid sweat, the team was able to provide a more realistic view of how these smelly compounds end up on our clothes.
The study also reveals some interesting insights about nylon and wool clothing. Apparently, while these fabrics initially absorb a lot of the odor-causing compounds, they also dissipate them faster than polyester.
After 24 hours, both wool and nylon had much lower odor intensity, similar to the less odorous cellulosic fibers.
Rachel stresses that these findings don't just apply to sportswear, but to all clothing, especially considering how much of our everyday clothing is made of polyester.
“If you're concerned about smelly clothes, stay away from polyester,” she advises.
“While hydrophilic cellulose fibers like cotton and viscose absorb more water from sweat than polyester, polyester doesn't want to absorb water,” she points out.
It is more oil-loving, absorbs more odors that are not soluble in water, and more oily compounds, which can also later decompose and become smelly.