What Are Antibacterial Fabrics? What Do 3A, 5A, and 7A Mean?

Antibacterial fabric is a type of functional textile. It either goes through antibacterial finishing or contains antibacterial fibers. As a result, it can help reduce bacterial growth on the fabric surface, control odor caused by bacteria, and keep the textile cleaner and more hygienic.

Antibacterial fabrics have a long history of use. Among natural materials, hemp fiber is one of the most common antibacterial fibers. This is mainly because hemp contains flavonoids, which can help inhibit bacterial growth. In addition, hemp fiber has a hollow internal structure. This structure helps increase oxygen content in the fiber and makes it harder for anaerobic bacteria to grow.

What Bacteria Can Antibacterial Fabrics Usually Inhibit?

After the pandemic, consumers have paid more attention to health, hygiene, and textile safety. Therefore, demand for antibacterial fabrics has continued to grow.

In textile testing, the common test bacteria usually include:

Escherichia coli

Staphylococcus aureus

Candida albicans

These microorganisms are often used to evaluate whether a fabric has effective antibacterial performance.

Antibacterial Grade Standards

Antibacterial grades usually depend on two main factors: washing durability and the antibacterial rate against different microorganisms.

In general:

3A antibacterial clothing means the fabric still has antibacterial performance after about 30 washes.

5A antibacterial clothing means the fabric still has antibacterial performance after about 100 washes.

7A antibacterial clothing means the fabric still has antibacterial performance after about 150 washes.

Therefore, a higher antibacterial grade usually means better washing durability and longer-lasting antibacterial performance.

Natural Antibacterial Fiber Fabrics

1. Hemp Fiber

Hemp fiber has natural antibacterial properties. Its antibacterial effect mainly comes from a small amount of phenolic substances inside the fiber.

At the same time, hemp fiber usually has a hollow structure and contains more oxygen. Its surface also has many grooves and gaps, which help moisture spread quickly. As a result, the fabric can reduce the damp environment that bacteria need for growth.

2. Bamboo Fiber

Bamboo fiber also has natural antibacterial properties. According to the processing method, it can be divided into natural bamboo fiber and bamboo viscose fiber.

Natural bamboo fiber is made through a combination of physical and chemical processes. The process is complex, and production is difficult. Therefore, pure natural bamboo fiber is not very common in the market.

In addition, natural bamboo fiber can feel relatively coarse and stiff. For this reason, manufacturers often blend it with cotton or viscose and use it in underwear, socks, bedding, and other textile products.

Regenerated Antibacterial Fiber Fabrics

Among regenerated antibacterial fibers, chitosan fiber and bamboo viscose fiber are two typical examples. In recent years, several plant-based antibacterial fibers have also appeared, such as mint fiber, sarcandra fiber, and aloe fiber.

1. Chitosan Fiber

Chitosan fiber comes from chitin after alkaline treatment and deacetylation. It is also known as deacetylated chitin fiber.

Chitosan fiber offers good broad-spectrum antibacterial performance, moisture absorption, and biodegradability. However, it is expensive. In many cases, the price can reach hundreds of thousands of yuan per ton, which limits its large-scale use in textile fabrics.

At present, manufacturers often blend chitosan fiber with cotton, rayon, or other cellulose fibers. The content usually stays below 20%. These blends are mainly used in skin-friendly fabrics, such as knitted underwear.

2. Bamboo Viscose Fiber

Bamboo viscose fiber is made by dissolving bamboo chips into pulp and then spinning the pulp through a wet spinning process. Its production process is similar to ordinary viscose.

Some studies suggest that bamboo fiber has antibacterial properties because it contains anthraquinone compounds with phenolic hydroxyl groups.

However, during the dissolution process, bamboo viscose loses part of the original natural structure of bamboo fiber. Some antibacterial substances may also decrease. Therefore, its antibacterial performance is usually weaker than natural bamboo fiber.

Even so, bamboo viscose is easier to process and has a soft handfeel. For this reason, most bamboo fiber products on the market are actually bamboo viscose fiber products.

3. Mint Fiber

Mint fiber is a newer type of plant-based antibacterial fiber. It uses advanced extraction technology to obtain active ingredients such as menthol from high-quality mint.

These active ingredients are added into viscose spinning solution before spinning. The process does not require additional chemical antibacterial agents. Therefore, mint fiber can offer good antibacterial performance and works well in blends with many other fibers.

Synthetic Antibacterial Fiber Fabrics

Synthetic antibacterial fibers mainly use antibacterial additives during the spinning process.

For example, manufacturers can add nano metal particles with antibacterial properties, such as silver, copper, and zinc, into the spinning solution of polyester, nylon, acrylic, and other synthetic fibers. They can also graft organic metal ions onto the fiber structure.

After spinning, these fibers can achieve more durable antibacterial performance.

Typical examples include:

Silver ion antibacterial fiber

Copper ion antibacterial fiber

These fibers are widely used in sportswear, socks, underwear, medical textiles, and other functional fabric products.

Modified Cotton Antibacterial Fabrics

Most antibacterial cotton fabrics gain their function through antibacterial finishing during the post-treatment process.

However, some finishing agents require a large amount of auxiliaries and may have limited washing durability. To improve this problem, some textile companies use plant extracts with antibacterial properties, such as mint, sarcandra, and isatis root, and graft them onto cotton fiber groups.

Other manufacturers use composite inorganic antibacterial technology. This method allows antibacterial components to penetrate into the fiber molecules, which helps improve washing durability.

Typical examples include herbal cotton fiber and IR antibacterial cotton.

Conclusion

Antibacterial fabrics can come from many different fiber routes. Some rely on natural antibacterial properties, such as hemp and bamboo. Some use regenerated materials, such as chitosan fiber or bamboo viscose. Others use synthetic fibers with silver ions, copper ions, or other antibacterial additives.

In addition, cotton fabrics can also achieve antibacterial performance through finishing, plant extract modification, or inorganic antibacterial technology.

When choosing antibacterial fabrics, it is important to look beyond the word “antibacterial.” Buyers should also consider the fiber type, antibacterial mechanism, washing durability, test bacteria, and antibacterial grade.

For underwear, socks, bedding, sportswear, medical textiles, and other close-contact products, antibacterial fabrics can help improve hygiene, comfort, and long-term product value.