Most conversations about denim sustainability begin with certifications, fibers, or finished garments. In reality, the biggest environmental decisions are made much earlier, inside spinning rooms, dye houses, and factory layouts that most people in fashion never see.
For decades, engineers have played a central role in shaping denim production behind the scenes. Among them is Paolo Leidi, an Italian denim engineer whose career has been spent inside mills across Europe, Asia, and the Americas, designing factories, upgrading machinery, and translating creative ideas into industrial reality.
Leidi entered the denim industry in 1987, following his father into a world defined by indigo and production problem-solving. Trained as a mechanical engineer, he never worked for a single company. Instead, he built his career as an independent consultant, an approach that demanded results rather than promises. Every mill, every country, and every machine revealed how denim is really made, and why many sustainability debates miss the core issues.
One of the clearest examples is indigo dyeing. Liquid indigo is widely acknowledged as more environmentally efficient than powder. It requires fewer chemicals, less hydrosulfite, and significantly less water, particularly for dark shades. It also simplifies wastewater treatment. Yet powder indigo is still used extensively.
The reason isn’t a lack of knowledge. It’s tradition, existing infrastructure, and relentless cost pressure. Mills operate in markets where every cent matters, while brands simultaneously demand lower prices and stronger sustainability claims, often without fully understanding the trade-offs inside production.
Machinery presents a similar challenge. Despite constant discussion around sustainability, many denim dyeing machines in use today are fundamentally unchanged from those installed decades ago. Incremental improvements exist, but meaningful reductions in water and chemical use require new technologies and the willingness to learn how to use them properly.
Nitrogen-sealed indigo dyeing systems, for example, can dramatically reduce hydrosulfite use, improve indigo fixation, and lower water consumption in washing. But these systems don’t work if they’re operated like traditional dye ranges. Without education and experimentation, mills hesitate to invest, reinforcing a cycle of stagnation.
Voluntary action alone won’t break that cycle. Real progress, Leidi argues, requires enforceable standards, especially around chemical use and water consumption. Measurement matters. Transparent data, independently verified, would change behavior faster than marketing commitments or paperwork-driven certifications.
There’s also a creative cost to the current system. As denim narrowed toward classic five-pocket jeans, mills lost opportunities to diversify. Indigo, however, is far older and more versatile than one garment type. Expanding its use across different fabrics and apparel categories could help mills operate more efficiently while justifying cleaner investment.
Ultimately, denim’s future depends less on slogans and more on listening to the people who understand production from the inside. Engineers and mill specialists may be invisible to consumers, but their decisions define denim’s true environmental footprint.
For a deeper technical discussion on indigo, machinery, and production decisions, listen to the full Jeansland podcast episode featuring Paolo Leidi, hosted by Andrew Olah.
