Bamboo Period Underwear: What’s Actually in Your Pair?

When we say bamboo period underwear, you deserve more than a bamboo leaf on the label. You deserve to know what the fabric is, what sits against your skin, and what is doing the work when your period arrives.

Our main fabric is 92% bamboo viscose and 8% elastane. The absorbent gusset uses a different mix of materials, because softness, stretch and leak protection each have a job to do. Here is what is in a pair of Rudies, and why we chose it.

What is bamboo period underwear made of?

Bamboo period underwear combines a bamboo-based body fabric with an absorbent panel in the crotch, called the gusset. The bamboo percentage on a product page does not necessarily describe every part of the garment. The body and the gusset can have quite different compositions.

For Rudie, the breakdown starts here:

• Main fabric: 92% bamboo viscose and 8% elastane.
• Gusset top: a soft cotton layer against your skin.
• Absorbent core: bamboo-and-cotton terry to absorb and hold fluid.
• Protective layer: a leak-resistant layer containing modal, seaweed fibre and elastane.

That is why we describe our range as bamboo period underwear, but never as a garment made entirely from bamboo. There is more going on inside a pair than one number can explain.

What we mean by bamboo viscose

Bamboo viscose is a manufactured fibre made using cellulose sourced from bamboo. The plant is processed into fibre, then made into yarn and fabric. It is not raw bamboo woven straight into your underwear.

We use it for the soft feel of our main fabric. If you are comparing labels, look for the fuller wording: viscose from bamboo, bamboo viscose, or rayon made from bamboo. That tells you more about the material than the word bamboo on its own.

It also helps separate the fabric from claims about the plant. You cannot assume that every property of growing bamboo carries through to the finished textile. The FTC's explanation of bamboo fabrics makes this distinction, including why natural antibacterial claims need evidence. We would rather explain the fabric clearly than ask one ingredient to promise everything.

Why we keep the other 8%

Elastane provides stretch and helps the fabric recover its shape. In underwear, that matters when you sit, move, pull a pair on and wash it ready for another wear. We want a fit that moves with you and stays comfortable.

When we rebuilt Rudie, we kept 8% elastane in the body because removing it meant losing the fit we wanted. It is a deliberate part of the blend, not a number we want to hide. You can read the longer development story in why we went dark.

So, is Rudie 100% bamboo? No. Is it entirely free of synthetic fibres? Also no. We think knowing the actual blend is more useful than a perfect-sounding claim that leaves out the stretch.

Inside the gusset: three different jobs

The gusset is the part that makes period underwear different from an everyday pair. It combines materials with different roles in a thin, multi-layer construction. The fabric around your hips and the fabric directly against you at the crotch are not the same.

First, the cotton top. This is the skin-contact layer of the gusset. It gives you a cotton surface where the absorbent panel sits, even though the surrounding body fabric is bamboo viscose with elastane.

Next, the absorbent core. Our core uses terry made from 70% bamboo viscose and 30% cotton. The thong and everyday brief use one core layer; the full-coverage high-waist brief uses two. That construction is part of why the styles have different absorbency ranges.

Then, the protective layer. This contains modal, seaweed fibre and elastane and forms part of the leak-resistant system. Seaweed fibre is one component of that layer. It does not mean the entire gusset is seaweed, or that the garment is plastic-free.

The practical point is simple: check both the body fabric and the gusset when you shop. A bamboo percentage tells you about a fabric blend. It does not tell you the full construction or how much fluid a pair holds.

Same main fabric, different levels of protection

Our three period styles share the 92% bamboo viscose and 8% elastane main fabric. The coverage and absorbent construction change to suit different days. Choose for your flow and the fit you like, rather than assuming every bamboo pair performs the same way.

• Leakproof Period Thong: 5 to 10 ml, for lighter days, spotting and backup, with the least coverage.
• Leakproof Period Brief: 10 to 15 ml, for light to moderate flow and an everyday brief fit.
• Leakproof High-Waist Brief: 20 to 25 ml, with fuller coverage and the highest absorbency in our range.

Those are our manufacturer reference ranges, not a promise that any pair will last a set number of hours on every body. Your flow changes across your cycle. Start by checking how a pair is working for you, and change it when it feels damp or approaches its capacity. Use backup protection when you need it.

If you prefer a thong but need more absorbency on a particular day, choosing a higher-capacity style or adding backup makes more sense than pushing a lighter pair beyond its job.

What to look for when you compare bamboo underwear

We would start with four things: the body composition, the gusset materials, the absorbency in millilitres, and the care instructions. Together, they tell you much more than a fabric name or a list of feel-good words.

Ask which part of the garment a percentage applies to. Look for a clear explanation of the absorbent layers. Check that the style suits your flow and that the shape gives you the coverage you want. A bigger bamboo percentage alone does not establish better leak protection.

It does not establish a health benefit or a lower environmental footprint on its own, either. Those are separate questions that need their own evidence. You should be able to choose a comfortable fabric without being asked to believe it does everything.

Looking after the fabric and the layers

Wash your Rudies before their first wear. After use, rinse in cold water until the water runs clear, then machine wash cold on a gentle cycle with similar colours. Skip fabric softener and bleach, and let them air dry instead of tumble drying.

Allow the gusset to dry completely before wearing the pair again. Having a spare pair makes that easier, especially when you are rotating between different absorbencies during your period. The aim is a simple wash-and-wear routine you can actually stick to.

A softer pair, with the details included

We chose bamboo viscose for our main fabric, kept elastane for stretch and fit, and built a separate gusset to handle your flow. Each part has a purpose. We want you to know those details before a pair reaches your underwear drawer.

If that sounds like what you are looking for, explore our bamboo period underwear. Start with the everyday brief for light to moderate days, the high-waist brief for more coverage and absorbency, or the thong for lighter days and backup. The right pair is the one that fits your day.