At ZD Zero Defects, we believe that true innovation in intimate apparel comes from respect for nature. That is why we incorporate soy yarn, a sustainable, biodegradable and exceptionally soft plant-based yarn, into our collections of underwear for women and men, as well as our socks.

What is soy yarn?

Soy yarn, also known as soy protein yarn, is obtained from the soybean seed and natural by-products such as soy milk or tofu. It is an environmentally responsible option, as it makes use of agricultural waste that would otherwise be discarded.

Thanks to its silky sheen and ultra-soft touch, soy yarn is often considered an eco-friendly alternative to silk. In textile applications, it combines the softness of silk, the breathability of cotton and the warmth of wool, offering a superior comfort experience even for the most delicate skin.

Properties of soy yarn

Soy yarn brings together unique natural benefits that make it a high-performance dermatological and sustainable fabric:

• High moisture absorption and breathability – Its porous structure absorbs and distributes body moisture, keeping the skin dry and helping to prevent irritation.

• Antibacterial and hypoallergenic – Acts as a natural barrier against bacteria and fungi, reducing odours and minimising skin irritation.

• Skin-nourishing and gentle – Its plant-based amino acids help maintain the skin’s natural hydration and support collagen production.

• Thermoregulating – Provides warmth in winter and freshness in summer, naturally adapting to body temperature.

• Biodegradable and sustainable – Made from by-products of tofu and soy milk production, helping to reduce agricultural waste.

A sustainable production process

1. Proteins are extracted from by-products of soy milk and tofu production.

2. These proteins are transformed into a manufactured organic yarn.

3. The yarn is then used to create garments.

4. The remaining material is reused as fertiliser.

A circular process that respects both skin and planet.

Who is soy yarn ideal for?

Soy yarn is the perfect fabric for those seeking well-being, comfort and dermatological care without compromising sustainability:

• People with sensitive, allergic or reactive skin

• Anyone looking for natural underwear without aggressive chemicals

• Lovers of sustainable and locally made fashion.

Perfect for sensitive and atopic skin

Soy yarn combines softness, breathability, thermal regulation and hypoallergenic properties, a powerful combination for anyone who needs fabrics that care for the skin rather than irritate it.

The yarn has a rounded and uniform structure, free from sharp edges or irregularities. This reduces friction against the skin, which is essential for sensitive, atopic or irritation-prone skin.

It is a softness that never scratches or aggravates inflamed areas.

Our soy yarn craftsmanship

At ZD Zero Defects, we transform this unique yarn into ecological underwear garments, crafted artisanally in our Barcelona factory since 1920.

Discover some of our designs:

• Atenea Maxi Brief

• Artemisa Long-Sleeve Undershirt

• Heracles Fly Front Boxer

• Ceres V-Neck Undershirt

Certifications and sustainability commitment

The soy yarn we use comes from non-GMO soybeans and complies with the OEKO-TEX Standard 100, guaranteeing it is safe for direct contact with the skin.

How to care for soy yarn garments

• Machine wash at max. 30ºC

• Do not dry clean

• Do not use bleach

• Do not tumble dry

• Do not iron

Natural comfort, tradition and sustainability

For more than a century, ZD Zero Defects has combined craftsmanship, innovation and sustainability to create garments that respect both your skin and the planet.