Why your synthetic gym shirt smells so bad, and top tips on removing the odor

Sep 26, 2023

Synthetic fibers are popular materials clothes, especially for sportswear and activewear. They have many advantages, such as being lightweight, durable, water-resistant, and wrinkle-free. However, they also have a HUGE drawback: they tend to smell worse than natural fibers like cotton or wool after being worn for a while, and oftenbthenodor lingers after washing. Why is that? And what can we do to prevent or remove the unpleasant odors from synthetic clothes?

The cause of bad smells

The main reason why synthetic fibers smell bad is because they harbor more bacteria than natural fibers. Bacteria are microscopic organisms that live on our skin and in our environment. They feed on the sweat, dead skin cells, and other organic substances that we produce or come into contact with. As they digest these substances, they release various noxious chemicals that cause body odor. In otherwords, your shirt smells because it's still not clean, even after washing.

Why synthetic fibers smell so bad

Synthetic fibers harbor bacteria and dirt

Synthetic fibers are more prone to bacterial growth than natural fibers for several reasons. First, synthetic fibers are usually hydrophobic, which means they repel water. This makes them dry faster than natural fibers, but it also prevents them from absorbing and releasing the sweat and dirt from our skin. It also means that water used for cleaning and rinsing has a hard time penetrating the fibers. Instead, these substances remain on the surface of the synthetic fibers, creating a favorable environment for bacteria to thrive.

Synthetic fabrics have a lot of room for bacteria

Second, synthetic fibers have a smoother and more uniform structure than natural fibers, which have irregular shapes and pores. The smooth surface is ideal for bacteria to attach and grow on, and the spaces between the fibers promote bacteria colonization. Moreover, some synthetic fibers, such as polyester and nylon, are lipophilic, which means they attract oil. This makes them more likely to retain the fatty acids and other oily compounds that bacteria feed on.

Chemically treated fibers can cause odor issues

Third, synthetic fibers are often treated with various chemicals, such as dyes, finishes, and coatings, to improve their appearance and performance. However, some of these chemicals may also affect bacterial growth on synthetic fibers. For example, some dyes may provide nutrients for bacteria, while some finishes may inhibit the natural antimicrobial properties of the fibers. And as mentioned above, hydrophobic coatings can make cleaning harder.

How to clean synthetic fibers to remove odor-causing bacteria

How can we clean synthetic clothes to remove the bad smell? The most common method is to wash them with laundry detergent in a washing machine or by hand. However, this method is often not very effective or efficient for several reasons. First, detergent and water may not be able to penetrate the hydrophobic synthetic fibers and remove the sweat and dirt from their surface. Second, detergent and water often doesn't kill all the bacteria on the synthetic fibers or prevent them from regrowing. Third, detergent and water may damage the synthetic fibers or reduce their quality over time.

Therefore, some alternative methods have been developed to clean synthetic clothes more effectively and efficiently. These methods include using antimicrobial agents, vinegar, baking soda, hydrogen peroxide, ozone, ultraviolet light, steam, or silver-based solutions like SWIFF spray. These methods aim to either kill the bacteria on the synthetic fibers or remove the substances that they feed on. Though killing the cause is the only effective way to stop odors, as once you wear the shirt again, any present bacteria will come out of dormancy and start feasting and stinking.

Antimicrobial agents to clean synthetic fibers

Antimicrobial agents are substances that can kill or inhibit the growth of microorganisms, such as bacteria. There are two main types of antimicrobial agents for textile applications: those that are applied to the textile during or after its production (such as silver or quaternary ammonium compounds), and those that are added to the washing solution (such as polyhexamethylene biguanide or triclosan). Antimicrobial agents can reduce or prevent the bacterial growth on synthetic fibers and thus eliminate or reduce the bad smell. However, they also have some limitations and drawbacks. For example,

Clothes that were commercially treated with antimicrobial agents, like fancy odor-atopping yoga pants, lose their effectiveness over time due to washing and wear.
Some antimicrobial agents may cause skin irritation or allergic reactions for some people.
Some antimicrobial agents may have negative environmental impacts due to their toxicity or persistence in water or soil.
Some antimicrobial agents may promote the development of antibiotic-resistant bacteria.

Vinegar as an acid to neutralize bacteria

Vinegar is a common household product that contains acetic acid. Vinegar can help to remove the bad smell from synthetic clothes by lowering the pH of the washing solution and thus inhibiting bacterial growth. Vinegar can also help to dissolve the fatty acids and other oily compounds that bacteria feed on. Note that the pH has to be fairly low to kill bacteria, which can also lead to fading of your clothes. Mlreover, the hydrophobic nature of synthetic fabric means that this approach is better suited for natural fibers. To use vinegar to clean clothes,

Add one cup of white vinegar to the washing machine along with your regular detergent.
Or soak your clothes in a solution of one part vinegar and four parts water for 30 minutes before washing them normally.
Note that the vinegar smell can linger until the acetic acid is fully washed out.

Baking soda as a base to kill bacteria

Baking soda is another common household product that contains sodium bicarbonate, which is a base (the opposite of an acid). Baking soda can help to remove the bad smell from synthetic clothes by neutralizing the acidic compounds that cause the odor and by breaking bacteria cell walls and membranes. Baking soda can also help to absorb some of the sweat and dirt from the surface of the synthetic fibers, but like vinegar it is better suited for natural fibers.. To use baking soda to clean clothes,

Add half a cup of baking soda to the washing machine along with your regular detergent.
Or sprinkle some baking soda on your clothes before putting them in a laundry bag or a sealed container for a few hours or overnight.
Baking soda also adsorbs odors, but that doesnt mean ots always killing the source.

Hydrogen peroxide as an oxidizing agent to kill smelly bacteria

Hydrogen peroxide is a chemical compound that contains 2 oxygen atoms and 2 hydrogen atoms. Hydrogen peroxide can help to remove the bad smell from synthetic clothes by oxidizing the organic substances that bacteria feed on, and can also kill bacteria when used appropriately. Hydrogen peroxide can also help to bleach some of the stains and discolorations from the synthetic fibers, but in turn can lead to fading of fabric. To use hydrogen peroxide to clean synthetic clothes,

Add half a cup of 3% hydrogen peroxide to the washing machine along with your regular detergent. This won't kill thr bacteria but can help remove stains.
Or soak your synthetic clothes in a solution of one part hydrogen peroxide and six parts water for 60 minutes before washing them normally.
Note that 3% hydrogen peroxide is generally required to kill bacteria, and works best at elevated temperatures when exposed to thr bacteria for prolonged periods of time.

Ozone to generate free radicals that kill bacteria

Ozone is a gas that contains three atoms of oxygen. Ozone can help to remove the bad smell from synthetic clothes by oxidizing the organic substances that bacteria feed. Moreover, it csn interact with bacteria and cause free radicals that damage their membranes and DNA. But note, ozone is also toxic to humans, so safe use is critical. To use ozone to clean synthetic clothes,

Use a washing machine or a device that has an ozone generator or an ozone injection system. Note that some machines marketed to produce ozone don't always produce enough to be effective.
Or expose your synthetic clothes to ozone gas in a sealed container or a room with an ozone generator for a few hours or overnight. Ensure ventilation and that thr ozone is not leaking into occupied rooms or areas.

UV as a sterilization source to kill bacteria

Ultraviolet (UV) light is a type of electromagnetic radiation that has a wavelength shorter than visible light. We all know UV is bad and cancerous for humans, and it's the same for bacteria. Ultraviolet light can help to remove bad smells from synthetic clothes by damaging the DNA and RNA of bacteria and thus killing them. Ultraviolet light can also help to bleach some of the stains and discolorations from the synthetic fibers, but will fade fabric very quickly. To use ultraviolet light to clean synthetic clothes,

Use a washing machine or a device that has an ultraviolet lamp or an ultraviolet disinfection system. But note UV does not penetrate water that well.
Or expose your synthetic clothes to direct sunlight for a few hours or overnight.
Note that UV light will not penetrate deeply into the fabric, so its more effective for surface sterilization.

Steam as a source of heat to kill bacteria

Steam is water vapor that has been heated to a high temperature, and just like it can burn us, it can burn and kill bacteria. Steam can help to remove the bad smell from synthetic clothes by loosening and removing the sweat and dirt from the surface of the synthetic fibers. To use steam to clean synthetic clothes,

Use a washing machine or a device that has a steam function or a steam injection system.
Or use a handheld steamer or an iron with a steam function to steam your synthetic clothes for a few minutes.
Note that steam has to be in constant contact with bacteria for minutes to ensure it kills them, and fragrances steamers are likely not killing bacteria, they're just covering the smell.

Silver-based antimicrobial cleaning and deodorizing technologies like SWIFF Spray are the most effective solutions to odor

Silver has been used for thousands of years as an antimicrobial agent due to its safety and efficacy, and has recently found application in the odor eliminating space. However, most silver-based products use silver nanoparticles that are incorporated into the fabrics during manufacturing. Silver nanoparticles are 10x less effective than silver ions and lead to significant waste and pollution. These particles also easily dislodge and lose their efficacy. Some washing machines use silver ions for cleaning fabrics, and even though silver ions are more effective than silver nanoparticles, they're still 10x less effective than chelated silver.

SWIFF spray uses silver and a natural plant product (gallnut extract) to kill odors and odor causing bacteria and to prevent against them in the future. The plant extract anchors the silver to fabrics and prevents it from being washed out. Better yet, it's fragrance free because it actually works, and it can be used on any fabric.

Final tips for cleaning synthetic fabric

These are some of the methods that can help you to clean your synthetic clothes and remove the bad smells caused by bacteria. You should always follow the instructions and precautions provided by the manufacturers of your synthetic clothes and cleaning products, and test them on a small or hidden area before using them on the whole garment. You should also wash your synthetic clothes regularly, preferably after each use, and dry them thoroughly before storing them. By doing so, you can keep your synthetic clothes fresh, clean, and odor-free.