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BACKGROUND Coarse low grade wool holds a share of more than 40% of the worldwide production of 1.2 million tons per year. Wool hair with a diameter above 32.5 μm and recycled wool waste represent an important source of high quality keratin. An efficient and simple shaping procedure to form all‐keratin composites could open a new approach to utilise wool keratin for production of sustainable and biodegradable all‐keratin composite. RESULTS In this work the dissolution and regeneration of wool keratin was studied using a concentrated solution of calcium chloride–water–ethanol as solvent and thioglycolate as reducing agent to open disulphide bonds. Up to 70% of the wool keratin dissolved in the solvent at pH 7, 60 °C. After dilution with water a share of 80% of the total keratin could be obtained as regenerated composite structure while 20% of the protein remains in solution. Based on the model studies, all‐keratin composites were prepared by impregnation of wool with solvent followed by thermal consolidation in a heated press at 60 °C and 2.2–3.3 bar pressure. CONCLUSIONS The new method for production of all‐keratin composites permits production of a protein‐based bio‐composite, which opens new applications for low value coarse wool and recycled wool waste. By use of cheap chemicals and thermal consolidation in standard equipment scale‐up of the technology is expected to be straightforward and commercially feasible, leading to a bio‐based and biodegradable composite material. © 2019 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

In Europe, considerable amounts of bark are available from wood-processing industries such as forestry and timber production. Polyphenolic components can be collected by hot water extraction. The extracted compounds can then be applied as colorants in textile dyeing operations. In this study, a comparative assessment of four different tree species with regard to their colouristic potential for wool dyeing was performed. Aqueous extracts from alder, ash tree, spruce and oak bark were prepared and analysed for their total phenolic content and ultraviolet (UV) absorption at 360-370 nm. The extracts were used for metamordant dyeing by adding iron sulphate mordant (FeSO 4 9 7H 2 O). For comparison, iron salt-based dye lakes were prepared and used in dyeing experiments. For each tree species, a specific correlation between the total phenolic content of the dyebath and the colour depth in terms of K/S and CIELab coordinates was observed, both for the aqueous extracts and the dye lakes. Based on this relationship, standardisation and quality control of raw materials and dye lakes can be installed as important stages in the industrialisation of natural colorants from bark. The preparation of concentrated dye lakes permits formation of a concentrated colorant as dye product, which then can be standardised and delivered to textile dyehouses, similar to synthetic dyes. The preparation of dye lakes offers a relevant route towards achieving the commercialisation of bark extracts as natural colorants.