Why does my t-shirt smell bad?

A few chromatographic analyses, spectrometric detection and around twenty t-shirt washing sessions later, these courageous odor explorers came to the following conclusion:

• The polyester part was more likely to retain bad odors ,
• It also had the particularity of keeping them even after washing.

For what ?

For a material, what will make the main difference in terms of odors is what it will choose to retain between its fibers once our perspiration has passed through them.

And synthetic fibers, including polyester in particular, are champions in one area: that of expressly retaining bacterial and acidic waste that “smells bad”.

According to Doctor Rachel McQueen , this is where two other chemical characteristics of the synthetic fiber come into play:

• She hates water,
• She loves oily substances.

It will therefore get rid of the liquid part of our perspiration as quickly as possible. possible by evaporation . Then, on the walls of its plastic fibers, all that will remain is the oily substances of our perspiration, which will only ask to join the carefully chosen odorous bacteria.

It is therefore because the fiber expressly selects smelly bacteria that our perspiration will not emit the same odor on a polyester t-shirt as on another material. This smell is significantly more aggressive on petroleum fibers.

To bring it back to life, researchers from the University of Ghent (Belgium), including Professor Nico Boon and Doctor Chris Callewaert, discovered another source of pungent odor: micrococcus.

No, it's not a species of orchid, but a smelly bacteria that doesn't like life in natural fibers, unlike another environment where it enjoys itself quite well: synthetic fibers.

Note also that regarding viscose, no smelly bacteria was found during the experiment at the University of Ghent. If you buy a jacket or coat, on the lining side, you can therefore favor this material .

As for nylon, it is an excellent refuge for proprionibacteriums, a source of acne and bad odors. Avoid t-shirts made of nylon.

“Ok, so I find myself at the end of the day with a t-shirt whose fibers are loaded with bacterial waste of all kinds. A wash in the washing machine and it’s gone, right?”

Well, our researchers have addressed this question well too. But you can guess the answer yourself from the characteristics of synthetic mentioned above.

A characteristic which will particularly manifest itself when the water from your machine seeks to wash your clothing of its microbes.

Did you find it?

This is indeed hydrophobia: body moisture will not be the only liquid quickly rejected by matter. Water and detergent will also have difficulty acting on it.

Elastic fibers, such as lycra or elastane, constitute the most extreme cases of hydrophobicity. This is why your sports clothes made from excessively stretchy material will be the most capricious when washed.

The threads of your plastic clothing therefore remain valiantly attached to body oils full of bacterial waste, to which will be added the different chemical agents who have tried to act on it during washing.

However well-intentioned, practices aimed at saving energy consumption such as the use of cold water or machines that limit the use of water do not help the phenomenon. They make killing bacteria even more complicated.

We can of course add to all of these factors the fact that synthetic clothing, unlike natural materials, is not very breathable and therefore encourages our perspiration.

So all these factors just add up.

If I were you, I'd think twice before grabbing this pack of five polyamide t-shirts to get through mid-season. Or summer. Or winter. Anyway, get out of this store.

If your synthetic clothes still smell after being put in the machine, it is not necessarily too late for them: Benoît recommends this detergent to promote better elimination of bacteria at the same temperature.

TECHNICAL SYNTHETIC, A MAGIC SOLUTION?

But what is the secret of all these underwear that claim to be technical and promise us a dry, odor-free life?

However, they are made of mainly synthetic materials. They should therefore behave in the same way in the event of intense effort.

Well, most of these brands simply use chemical agents that wait for our smelly bacteria to attack their skin. These will often be silver-based agents with bactericidal properties.

This therefore gives a stretchy, dry and non-odorous garment, thanks to the hydrophobicity of synthetic fibers and the other advantages they can have. Hence the abundant supply of this type of material in the field of sportswear.

For example, Polygiene fabric technology uses silver salts to inhibit smelly bacteria.

This practice, although effective during the first ports, nevertheless presents certain limits:

• Their effectiveness decreases with each wash.
• It also finds its limits from a certain quantity of perspiration
• The biocides used do not only destroy smelly bacteria.

This last point is all the more important because brands are increasingly using nanoparticles.

Nico Boon, microbial ecologist at the University of Ghent, specifies that these biocides could potentially impact our immune systems.

In short, we do not know their long-term effects precisely enough. Even if for the moment, we are at the questioning stage.

On the environmental side, the researcher specializing in nanomaterials Eric Gaffet affirms that from a certain concentration, the nanoparticles used can be harmful to the reproduction of aquatic species. They can also kill bacteria needed for wastewater treatment.

However, this type of impact will still depend on the manufacturing methods used by a brand. This therefore falls into the hands of their eco-responsibility and their management of industrial waste which involves issues going well beyond.

As this article from 60 million consumers tells us, nanoparticles are therefore in the crosshairs of control bodies. European regulations require the mention of the term “nano” on products. A regulation that can be avoided beyond a certain particle diameter, as the Uniqlo brand has done for its Airism range.

Another approach makes it possible to limit perspiration and the negative effects linked to the constitution of synthetic fibers: it focuses on the weaving itself and the way in which the fiber is used.

Here, we are on something completely different: rather than masking the damage with biocides, subject is studied in itself + to resolve the problem at the source, by optimizing breathability and ventilation when worn.

This is the case of Gore Tex fabric in particular, whose pores are designed to be small enough not to let water through but large enough to evacuate humidity and body heat +.

Polartec is also well known for excelling in this type of technology thanks to their research and development policy: the Power Dry and Power Stretch ranges are very good examples.

And unlike synthetic fibers:

• Cotton is not a magnet for smelly bacteria,
• It is not hydrophobic.

Result ? Much more effective washes, with a high score in bacteria killed.

The downside, particularly in a sporting setting, is that a cotton t-shirt will take longer to dry: the unpleasant sensation linked to humidity risks sticking to your skin for longer than with a t-shirt. plastic "dry fit" shirt.

LINEN, FOR A SMART SUMMER

Like cotton, linen is a fiber of plant origin, with the only difference being that it does not come from a flower but from the inside of the plant stem. We therefore say that linen is Liberian.

All of its properties relating to humidity and bacteria will therefore be quite similar to those of cotton.

Linen will absorb body moisture just like cotton. It is its hydrophilic pectins, binding the fibers together, which give it this ability to absorb up to 20% of their weight in humidity, without changing the sensation to the touch.

All without exclusive preservation of bad bacteria unlike synthetic fibers. Since linen also has anti-bacterial properties.

Linen fiber also dries quite quickly.

These same pectins also make linen extremely thermoregulatory: depending on the external climatic conditions, this living material will adapt to keep you warm or, conversely, cool.

Here, unlike cotton, it is no longer a simple boost but a real asset for regulating your body heat.

The downside is that linen is rough. Next to the skin, it will probably itch more than cotton but will still be excellent to wear as a shirt in the summer. Because it will let air pass between your skin and the fabric.

But if you are comfortable, unless you move upmarket to higher fiber and weave qualities, I would not wear a linen t-shirt under my winter sweater for you . A great alternative can be a cotton-linen blend, resulting in a softer, less wrinkled fabric.

WOOL, THE INDEPENDENT QUEEN

The majority of research has come to one conclusion: when it comes to odor inhibition, wool remains unbeatable.

It shows an excellent ability to absorb humidity without allowing smelly bacteria to proliferate. And this absorption can go up to 35% of its weight!

Then, she lets it all evaporate while keeping the human body warm, even when wet.

Another New Zealand study cited by the Reset Center showed that wool retained 66% less odor than polyester and 28% less than cotton.

The fineness and natural constitution of the wool fiber gives it magical thermoregulatory powers that man has tried to reproduce artificially for decades.

And as with linen, this thermoregulation will limit your body's needs for moisture evacuation.

Whether upstream or downstream of this phenomenon of body heat rejection, wool is our champion here. With merino wool at the forefront, finer and therefore more often used as a base layer.

And since it retains the least odor, it can be washed less frequently than for cotton or polyester. A wash which will still be more restrictive, since it will be necessary to maintain your piece gently, like a knit.

This is why merino wool is the great favorite of hikers, travelers, and Benoît.

For sports use, its drying time still remains 50% slower compared to synthetic. But at this price, you remain a step above in terms of hygiene.

DON’T NEGLECT THE TOP LAYERS

Obviously, these tips should be taken into account whatever the “level” of the layer of clothing in question.

Whether it's your trench, your sweater, or your shirt, it is therefore important to turn to natural materials (or technical in certain cases) so as not to make your investment in a t-shirt useless. wool for more than €50. Although a synthetic outerwear worn over a natural base layer is better than the same combination with a polyester t-shirt.

THE FINAL WORD

You will have understood, poly-oil will not be on the podium today.

You now know why, if your budget allows it, the merino base layer remains a holy grail (quickly addictive) in all seasons. So he is in first place.

For smaller envelopes, in second place, 100% cotton pieces will be the best compromise under layering.

Linen is an excellent alternative, with better thermoregulation than cotton. But it will be more pleasant on a loose piece in summer than stuck between your skin and a fitted sweater.

Now, when a friend asks you which t-shirt composition to choose, you will have a complete answer to say the least. Start by inviting him to sit down.