What smells so good on clothes dried in the sun?

the sunny yard seems to "inject soul" into laundry-many people feel that there seems to be a particularly good "fresh smell" on clothes dried naturally in the sun after washing.

what on earth is this "smell of sunshine"? Until recently, a chemical study finally answered.

reproduce the smell of the Sun

Sylvia Puglitz (Silvia Pugliese) is the lead author of the study. For her, the fresh smell of drying clothes on the clothesline is full of "memories of home." When Puglitz was studying for a master's degree at the University of Copenhagen, she and several lab partners studied the odor chemistry of drying clothes between more formal research work.

to reproduce the smell of sunlight, researchers naturally start with cleaning and drying-but this time, according to strict experimental standards. To rule out odor factors that have nothing to do with the drying process, the researchers found new cotton towels that had never been washed before and used only ultra-pure water to complete the washing process. After three times of washing, the wet towels dried naturally in sunny outdoor, sheltered outdoor, and indoor environments. After drying, the towels are packed into sealed sampling bags to collect odor substances for analysis.

A small balcony for drying experimental towels | Silvia Pugliese

what on earth smells so good?

the researchers analyzed these towels and the control group by gas chromatography-mass spectrometry (GC-MS). It turned out that they did find a series of unique "aroma molecules" on towels dried in the outdoor sun, most of which were small aldehydes and ketones containing 5-9 carbon atoms. They should be the chemicals behind the "smell of sunlight".

part of the odor molecules produced by fabric drying in the sun

these small molecules produced in the sun are pleasant, and some are even used in perfumes. For example, these substances include 2-methylpropionaldehyde, which is described as "fruit, baked aroma"; there is also 2-methacrolein, which has a "floral scent".

these molecules have a small "odor threshold"-that is, just a little bit is enough to be perceived by a person's sense of smell. Not only that, but these polar small molecules can also form hydrogen bonds with cotton fibers, allowing them to "stay fragrant" on the fabric for longer.

Make your fashion dreams come alive with our red and black prom dresses. Buy now to enjoy best customer care and fastest delivery.

where do they come from?

so how are these odor molecules formed? These small molecules should have been born in a series of oxidation reactions, and the precursors that produced them may have come from the surrounding environment or may have existed on towels in the first place, and their sources are still uncertain.

the occurrence of oxidation may be related to ozone, but the author thinks that photochemical reaction is a more important factor. Under the excitation of ultraviolet rays in sunlight, some substances produce highly reactive free radicals, which trigger subsequent reactions. A similar reaction may take place not only on clothes that are dried but on other wet surfaces outside.

at present, there are still many doubts about the smell of drying clothes. But thankfully, someone is willing to study it.