Zero waste nettle – process optimization to refine nettle (Urtica dioica) into multi-purpose materials: textile fibres and colorants

Sustainability related policy objectives integrate with biodiversity issues. Current agri-food systems hold potential in diversifying the material basket, whilst novel crops can hold multi-purpose characteristics that can improve resource efficiency. Equally, the textiles and fibre industry could use ecologically more feasible and localized options. Our aim is to develop more sustainable solutions for fashion and textile production by focusing on high performance natural fibres and colourants and upgrading of materials’ values. In this presentation we showcase the various and unique properties of nettle (Urtica dioica), a perennial low input multi-purpose crop holding economic and ecological advantages. Nettle is a historical and previously industrially used fibre crop providing high textile grade fibre and food within the same harvest. The traditional fibre processing method, which starts with mechanical extraction of bark either before or after water retting, generates soft, shiny and flexible fibres, ideal for fine textiles applications Optimized water-based processing followed by retting generates wastewater however, potentially offering a source of natural colourants to be used in various applications. The study utilizes nettle stem biomass originating from a farm in Finland, that currently processes leaf biomass into food-products whilst leaving the stem biomass unused. When selecting the most optimal biomass processing method for fibre refining, cooperation with natural colourant production could be a feasible option for processing wastewater from primary retting phase when operating off farm. Our presentation showcases the colour variety obtained from nettle on bamboo viscose, cotton and wool materials, and discusses the obtained colour and the chemical composition of the dye.