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Image Credit: Edward Cwik, CC BY-SA 3.0, via Wikimedia Commons
Natural Collagen Treatment Could Help Protect Historic Leather Objects
A new heritage science study has tested a collagen-based treatment designed to strengthen and protect degraded leather objects. The research explores a collagen/epicatechin composite as a more sustainable approach for reinforcing vegetable-tanned leather, one of the most common types of leather found in archaeological contexts.
Leather heritage is highly vulnerable to environmental damage. Changes in humidity and temperature, ultraviolet light, air pollutants, and microbial activity can weaken collagen fibres, causing cracking, delamination, and internal structural deterioration. Traditional conservation treatments often use oils or coatings, but these can sometimes cause darkening, oxidation, tackiness, or long-term preservation problems.
The new approach combines collagen with epicatechin, a natural plant-derived polyphenol. Epicatechin can form hydrogen bonds with collagen, acting as a natural cross-linker while also providing antioxidant and antibacterial properties. The aim is not only to coat the surface, but to penetrate the leather matrix and help replenish degraded collagen.
The researchers tested the composite on artificially aged vegetable-tanned leather, including chestnut-tanned and betel-tanned samples. The treatment was applied by repeated brushing on both the grain and flesh sides, allowing the solution to gradually enter the leather structure.
Laboratory results showed that the collagen/epicatechin composite had strong antioxidant activity, with a DPPH radical-scavenging rate of about 88%. It also showed antibacterial performance, producing inhibition zones against E. coli and S. aureus. When applied to aged leather, the treatment reduced bacterial growth, especially against E. coli.
Microscopic analysis showed that treated leather had a denser and more continuous collagen fibre network. Internal pores and voids were partly filled, and the leather structure appeared more compact. This was supported by increased apparent density and reduced air permeability after treatment.
Mechanical testing also showed improvement. The treatment increased tensile strength and elongation at break, especially in severely degraded chestnut-tanned leather. Thermal analysis suggested improved stability, with higher decomposition temperatures and greater char residue after reinforcement.
However, the study also notes important conservation limits. The treatment caused some colour change, especially in chestnut-tanned leather, where the change was considered visually distinct. The authors also emphasize that the tests were performed on artificially aged modern leather, not authentic archaeological leather. Therefore, further validation on real heritage materials is still needed.
Overall, the research presents collagen/epicatechin composites as a promising preliminary strategy for strengthening degraded leather heritage. The method may offer reinforcement, antioxidant protection, and antibacterial action, but its long-term stability, reversibility, and visual impact must be carefully assessed before wider conservation use.
Published on: 22-06-2026
Edited by: Abdulmnam Samakie
Source: npj Heritage Science
