Your base layer is the unsung hero of outdoor gear. From natural fibers to fair labor practices and transparency, here’s what to look for when buying a performance base layer that stands up to both your adventures and your principles.

When assessing a base layer’s environmental footprint, start with the material. Popular natural fibers like merino wool, organic cotton, and hemp are biodegradable and require fewer synthetic chemicals during production. However, they aren’t without drawbacks—overgrazing is a concern for wool, while cotton farming often demands large amounts of water.

To find a base layer produced from sustainably grown materials, select those certified with ZQ Merino standard or Responsible Wool Standard for ethically sourced wool and GOTS for organic cotton. The wool labels encourage responsible welfare practices, traceable supply chains, fiber quality, and environmental and social accountability. GOTS label represents third-party verified textile production of organic cotton fibers that comply with environmental and social criteria. Some brands take it a step further, such as Devold, whose “sheep-to-shelf” process ensures traceable sourcing by raising sheep locally in order to control every bit of the process.

For those focused on durability, some brands meld synthetics like polyester with the natural fibers – or use only polyester. Make sure you choose synthetic materials that are recycled, in these cases.

Ethical manufacturing: The people behind your clothes

Behind every garment there are workers that produced it. As supply chains become longer and production faster, making sure that working conditions are fair becomes paramount. Ethical manufacturing represents setting fair wages, good working conditions, and reducing labor exploitation risks. When companies are transparent about how products are made, they invite consumers to hold them to those promises in a way that builds trust. In that way, transparency becomes a responsible brand’s usual practice, not just mere compliance.

When choosing base layers, look for brand affiliations to Fair Wear Foundation or Fair Trade Certified. For example, Vaude has been one of the pioneers in making its production chain conform to the principles on labor rights and has been holding a Leader status with the Fair Wear Foundation for transparency about production locations and factory conditions.

Built to last: Durability equals sustainability

The most sustainable base layer may be the one you never have to replace. Durability plays a key role in sustainability—long-lasting garments reduce waste and minimize the need for frequent replacements. Since producing and shipping new products comes with a significant environmental cost, choosing a high-quality, durable product benefits both you and the planet.

Brands like Rab support durability through rigorous testing and design focused on quality. When choosing a base layer, look for reinforced seams, abrasion-resistant fabrics, and product warranties. A brand that is willing to stand behind its product with a guarantee shows confidence in its longevity. Good examples of such brands are Ridge Merino and Pnuma Outdoors that provide lifetime warranty on the quality of their products.

Performance meets sustainability

A base layer isn’t worth much if it doesn’t perform. Moisture-wicking, breathability, and temperature regulation are non-negotiables. But these features don’t have to come at the expense of sustainability. It all comes down to matching the material to your activity level.

For moderate activities, lightweight merino blends will work great, but for high-intensity pursuits where drying quickly is important, recycled synthetics may be a better option. Merino wool is ranked high among natural options, unbeatable in breathability and odor resistance. In the category of synthetics, recycled polyester can offer similar performance, especially with sweat regulation. A pioneer in this regard, Patagonia integrates recycled materials into their base layers without any compromise in technical excellence.

Versatility: One garment, many lives

If you can use your base layers in a multitude of activities, you’ll need to own fewer pieces. Stick with neutral tones and minimalist designs that extend their utility well beyond the trail. Look for a design you can wear on hikes, to a yoga class, or just around the city.

Smartwool, for instance, makes Merino wool base layers that look good under a ski jacket but also when paired with jeans.

Demand verified transparency from the brands

In an era where greenwashing is a growing concern, voluntary transparency from brands is a strong indicator of their commitment to sustainability. Brands that openly share sourcing, manufacturing, and sustainability practices demonstrate genuine accountability.

Cotopaxi is an example of transparency done right: they assess their subcontractors through annual audits and showcase some of their producer companies on their website. They also require suppliers to sign a Code of Conduct which prohibits unauthorized subcontracting. Look for such practices when evaluating your purchase options.

Another measure of responsible production is certifications: look for stamps of approval from responsible bodies such as Oeko-Tex, Bluesign, or Cradle to Cradle. These are third-party verifications of a brand’s sustainable claims that separate marketing claims from real efforts.

Take good care of your base layers

Proper care extends the life of your base layers, making them more sustainable. Air-dry them instead of using a dryer, as heat can degrade fibers. Wash them less frequently and only in cold water to preserve fabric integrity. When your base layers reach the end of their life, look into recycling options—many brands offer take-back programs to help repurpose old garments.

Conclusion: your choices can make a difference

Every choice you make creates a ripple effect that influences how brands produce their goods, how workers are treated, and how resources are consumed. When you opt for base layers that prioritize ethical manufacturing, durable materials, and transparent practices, you’re voting for a better way of doing business. You’re showing that functionality and sustainability don’t have to be at odds—they can coexist.

Whether you’re summiting peaks, hitting the slopes, or just out for a morning run, make sure your base layer does more than keep you warm. Let it reflect your values. Because when your gear aligns with your ethos, every adventure can become a statement for the world you want to see.

Illustration by Padraig Croke