How paper waste can get up-cycled instead of down-cycled – the case of Honext

Barcelona-based startup Honext has developed a way to transform paper waste into panels, using materials which already exist rather than consuming raw materials 

Recycling paper doesn’t guarantee a closed loop

In 2011, Honext was established together with researchers from the Politecnico University of Catalonia and three generations of the Merino family. This Barcelona-based startup has developed a method to up-cycle paper waste into non-toxic panels for interior purposes. Their aim was to transform university lab samples into a commercialized product. Of course, paper gets recycled everyday, tackling climate change in a more subtle way for everyone to do. However, as they continue getting down-cycled, the cellulose fibers of the paper become too short to be bonded again. This is when waste management companies incinerate, leaving a gap in the circular economy. 

Honext: Panels made from paper waste

«Our DNA is based on R&D», says Honext Brand Manager, Berta Julià Sala. The detailed process is patented, but the concept follows the upcycling of the cellulose waste through a bio-technological process which involves certain enzymes. It takes the short fibers of cellulose and transforms them into stronger cellulose fibers. This is what allows them to disregard one of the most toxic elements in panel production: resins. Given the abundance of cellulose in the environment, there is a lot of R&D dedicated to finding uses for it. 

Most of it takes into consideration sustainability and circularity. Honext has some other patents which foresees further applications for it in other products. One potential example is using other cellulose-based products and food waste. However, scaling up is the complicated part, especially when it comes to making standardized materials. 

«You can see thousands of materials coming out everyday from designers to chemists. Everyone is talking about bio-plastics and plastics coming from algae and furniture made with mushrooms, which is of course possible. Scaling up is the difficult part», admits Sala. They specialize in boards and panels, an industry which they believe could have the strongest impact. For now, these panels are for interior design purposes as they lack structural integrity. However, Sala points out that «the mechanical and thermo-dynamic properties and sound absorption, in some cases, is better than MDF (Medium-density fiberboard)».

The types of waste to use

An ideal element to include in a completely circular world would be to gather all sorts of waste and transform it into something else. Given that our technology is simply not there yet, there is the need to categorize and separate waste based on their properties and qualities. For the current product at Honext, they use two types of waste. The first type of waste is the primary sludge. This is industrial waste which comes directly from paper mills and recycling plants. 

As mentioned before, there is always a down-cycling of the paper in recycling it again and again. Therefore, once these mills and plants consider the waste to be in the last phase of its life, they supply it to Honext to take care of. This supply of primary sludge includes various types of paper, at slightly different times of their life cycle. The quality that comes to them is always a bit different. This is why the company adds a second type of paper waste to the mix: cardboard from the consumer. This is a practice to balance the quality of the fibers. Their factory is inside of a landfill in Vacarisses, Barcelona, so the waste they use comes from around the area.

Lampoon, Non-toxic panels, Honext
Non-toxic panels for interior purposes, Honext

The production process: Sourcing through the impurities

There is the waste sourcing or sorting that depends on the quality of the primary sludge. There is the need to analyze it to determine the overall percentage to use. How much cardboard to add. The poorer the quality of the sludge, the more cardboard to add, to balance out the properties. Usually, the sludge contains a lot of humidity. In some cases, paper mills and recycling plants dry it out before they send it off to facilitate transport as it weighs less and takes up less space. 

Whatever the case, the sludge goes through a process in which the larger impurities are removed. This includes plastic because of thin films which may be found on the cardboard. This is true also for metal parts which may be found in smaller quantities. When this stage is over, small particles of impurities may still be present, such as micro-plastics. All of this is mixed to then add the patented bio-technology, creating stronger bonds between the hydrogen molecules of the cellulose fibers. This mix goes into a press which presses them into a wet panel. The final stage consists of passing the wet panel through a drying tunnel.

Transportation in a circular economy 

Processes can continuedeveloping to make production chains more circular and sustainable. However, one element which seems to go by unnoticed in many manufacturing plans is the transport post-production. Transporting a product from one factory to the next or from a factory to a shop takes time, money and energy. Reducing the distance between these hotspots would inevitably help reduce carbon emissions and footprints. 

This is why Sala explains that a next step to take would be to create networks within landfills to minimize all sorts of transportation. This would also help control each market better; as their division into smaller networks. Although the technology is high-tech, «it is quite modular», explains Sala. This would aid in the diffusion of the manufacturing process; easily replicable. «The energy we use is also waste because it comes from the landfill. We use bio-gas that comes from the biodegradation from the organic matter from the landfill to run our factory», says Sala. They also use the water created during the biodegradation. Filtering it during the recycling process. 

The difference between up-cycled boards and traditional panels 

Traditional fiber boards and panels come from raw materials such as wood. Additionally, they use resins, VOCs (Volatile organic compounds) and other toxic additives. Due to the exclusion of resins in their board production, there is the possibility to up-cycle the material again. «Most particle and fiber boards come from wood; and this wood comes from trees, cut only for this reason», Sala points out. «We are using something that nobody else would use». 

Although they are using waste as a material to count towards sustainable and circular production practices, the waste itself may hold some elements which aren’t so eco-friendly. As mentioned before, the cardboard may leave some micro-plastics and other micro-impurities even after the process. It may also contain some other forms of toxic additives which are already in the cardboard. However, Sala explains that they «can’t do much about that» and that in any case, the level present is much less than the permitted limit. 

«Other than the product, the whole business concept we created is already more sustainable». The end product is the base product, a board without added colors or textures. It is a grayish-beige board that buyers buy directly; who decide what to do with it. Whether that be coloring it with toxic dyes or adding natural textures depending on the interior design. The core materials in any type of manufacturing in the future may comes from the most sustainable of intentions. However, then end decisions always lies within the consumer mindset.

Biodegradability versus zero-waste  

«Part of our material is plastic and things which aren’t organic so you can’t biodegrade the product», admits Sala. A high percentage of the end product may biodegrate; but it wouldn’t be able to fully do it given the extent of what compose it. Nevertheless, their production is Cradle to Cradle certified, ensuring that their production process is circular. Although there is a limitation in the extent of biodegradability as a property, the concept aims for a zero waste future. 

«All waste should be a resource for something new», explains Sala. «Its just that as a society, and as an economy, we dont have this mindset of understanding waste as a resource for new things. We all live on this linear economy basis. If we were to start thinking that everything we create is valuable for something else, we would definitely reach a zero waste future». Creating a recyclable product is one thing, but integrating it within a closed-loop economy is another. This would enable items which aren’t necessarily fully biodegradable, to still act within a circular system. 

Although there is still a way to go, changes should occur in the short-term rather than in the long-run. This is because setting up new companies with a circular economy framework already in place is easier for them to adapt to sustainability changes, rather than for «established companies who are already based in linear economies», explains Sala. Keeping companies within smaller networks, working towards a zero waste future and inside of a closed loop economy could be a way to tackle sustainable production, across multiple industries, in manageable chunks. 


Is a Barcelona-based startup that up-cycles paper waste and cellulosic fibers into recyclable panels using a patented bio-technology process. They receive the waste from paper mills and recycling plants to encourage zero-waste production. 

India Gustin

The writer does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article.