Last year, we launched our first plant-dyed models – a project that is dear to us and we vowed to continue and get more involved with it.
This year we have launched the model Hope, which was custom-dyed for us by our partners at Minority Denim, an innovative small business from Famalicão, Portugal.
We took this opportunity to see the plant-dyeing processes in person and chatted with founder Diogo Aguiar about the project Biotint, a dying process only with plants, sustainability in textiles and their future.
Let’s peel the layers of this richly coloured Onion together!

- Could you please tell us a little about Minority Denim and its history so far?
The idea for the project came in 2009, when I was working for a multinational textile company in La Coruña, Spain, and we had a lot of time to think about what was missing in the industry.
I realised that there was a lack of an independent company, with the knowledge about production but fewer creative limitations, that could invert the process of traditional production and eventually turn this creativity into a profitable business.
It started as a consulting company back in 2015, where we developed collections and recipes that brands could then use for production. On the side, we ran a home laboratory where we started investigating new, innovative recipes with sustainability in mind.
- How did Biotint come into being?
Biotint came from our knowledge of direct and reactive dyeing. We were asking ourselves whether we could do more and we started investigating more deeply the natural dyeing process, which was the path we wanted to explore.
We knew that it was done at home by crafters with good results, so adding our industry knowledge we thought we could improve on those results.
The testing started in a basement in 2017, using a small machine that could handle up to 1kg and using my mother’s pots. We researched and cataloged different variants to get the best results for the color, lightfastness and friction resistance. We experimented with the intention of finding a process that was scalable while also achieving the best quality.
We launched in 2020, just before the pandemic hit, and our then main business was quite affected, so we decided to focus on Biotint during this period. We took this time to develop a machine that would allow us to go from a 10kg capacity closer to 60kg.
Focusing on Biotint brought responsibility and sustainability to the forefront, as times such as these make us think about the effects of a sanitary crisis.
That is how we got to where we are now.
- What is your main mission and why?
Minority Denim still works on the investigation and development of denim treatment, especially washes, which is our specialty. We place the focus on sustainability, on avoiding the most toxic products and contact of our technicians with them and reducing water and energy consumption.
With Biotint, our current goal for the year is to expand our production capacity from 50-60 kg to 100kg or more a day of textiles dyed with 100% natural materials.
- How do you see the natural dyes and the textile industry evolving?
Right now, we work for a very specific niche, as not everyone is yet ready to take certain care steps. When it becomes a low-cost product, if it ever does, it could create more problems than solutions.
Imagine that we produce a series of t-shirts for a fast fashion brand, to be sold for 10€ or 9,90€ and that the communication is not done properly – the clients would not care properly for the t-shirts and we could have a high return rate, maybe higher than 50% (with the current easy return policies). If we’d have a return percentage superior to 50% in a production of 30000 or 50000 pieces, it would mean a big failure in terms of sustainability. The increase in fuel and logistics would be enormous and the worst is that the rejected pieces would end up in the trash!
I believe that there is room for growth, but not necessarily a mass product.
If the giants of the industry decide to incorporate our way of thinking and apply their huge marketing capabilities, they might reach a high number of people, but I don’t see that as beneficial. That’s why I believe this product is for the “minority” and not the “majority”.

- Can you please explain the process of plant-dyeing in more detail?
Yes, of course. For your sneakers, we use the product called Onion 30, which is one of our options for natural dyeing with onions. This one gives the fabric a rose tone while Onion Plus gives it more of a brown tone.
In this case, we source the onions from two big producers in Póvoa do Varzim and Peniche, which have a guaranteed stock of about 2500 kg of onion peels.
I believe this is the strongest product, especially in terms of sustainability, as we pay local farmers for the onion peels, something that wasn’t previously profitable for them.
We pick them up, then do an internal triage for storage. We catalog all of the peels by origin and date, as there is a difference between summer and winter harvests, so we can make adjustments when needed.
- Where do the raw materials come from?
Aside from the onions, we are quite focused on Eucalyptus leaves. I have contacts with the groups that clean the forests. They let us know when they are going to clean up an area. We go there, get the leaves, then let them dry, sort them one by one and extract the dye, after they go into the compost, just like the onion peels. The process with wood is the same, we get them from local carpenters, and so on with all of the other raw materials.
- Does the process work with any materials/textiles?
We are most familiar with cotton, silk, and wool, but we’ve tested other materials.
With Mukishoes we gained experience with hemp and it was a good surprise. Working with you on that project has been very gratifying.
- Are these colours permanent? How are they fixed?
The colours are fixed through natural processes. Once the dyeing is finished we either fix them through temperature or chemical reaction between natural substances, the mordant and the color.
- And what are the limitations of natural dyes?
The biggest limitation we have found so far is the unavailability of certain raw materials when we need them.
Getting the coffee leftovers can also be an issue, as they can’t be sold by coffee shops, we can’t write an invoice for them, as they are legally considered to be trash, so we had to find other ways to compensate them like making smaller products for them to gift their clients during the holidays for instance.

- Should we use any special care when handling plant-dyed products?
It is important to never let the fabric dry directly in the sun and always wash it with water and neutral soap. If you use a regular detergent and rub it vigorously it will likely stain but if you take proper care, the color should last a good while.
- Is this process more water efficient?
We haven’t achieved a big improvement in the consumption of water compared to other processes. What is important to note is that all of the water that we send back to the line, while it is obviously not potable, it is not toxic either.
- So there is no need to filter these waters?
No, they are non-toxic. And soon we hope that they can be used for irrigation, that is one of the main goals we are working towards. The only reason it hasn’t happened yet is that we need to perform further testing, store more water and neutralize its pH values to make it suitable for that activity.
Thank you Diogo for explaining and bringing this wonderful project to life.
We are happy to work together with you and we are excited about future colours!
Our model Hope, dyed using Minority Denim’s Onion 30, is available with the Mukishoes SS23 collection.