Abstract

Providing peculiar enhanced features to leather items is a factor of primary importance for the marketing of high-end articles; although tanning production is oriented to satisfy a wide market range, it is mainly in the ʻhigh endʼ and ʻpremium luxuryʼ categories that the quality properties of the material are more expressed, indeed. It is particularly on this market segment that the main current challenges have been focussed, according to the growing requirement of technological innovation, sustainability and product quality.

Light-coloured leathers, with particular reference to white items, belong to the category of materials designed especially for the luxury market. For this type of articles, the uniformity of colour and the agreeable appeal of the overall surface appearance are crucial requirements for the most international fashion and luxury brands.

One of the most common and undesirable defects of this type of article is the alteration of the colour, with particular reference to the localised or diffused effects of yellowing of the surface of the material. There are several causes able to contribute to the production of this type of defects, due to the complexity of the matrix and to the variability of traditional or innovative production processes used: from the intrinsic fragility, photosensitivity and thermo-sensitivity of the finishing polymers, to the chemical instability of some components of the finishing pigments, further the presence of photosensitive chemical additives, the migration of skin components or assembly components of the manufactured articles (fats, fillers, plasticisers, glues etc.), up to the indirect contribution of environmental and thermo-climatic factors able to affect negatively the performance of the material.

SSIP, which has always been involved in research and consulting activities for the leather industry with regards to defect monitoring, through this work, would offer an overview of all the main tools for advanced diagnostics (with particular reference to Scanning Electronic Microscopy and to chromatographic and spectroscopic methods) aimed to the identification of the causes of yellowing, beside to explore innovative solutions for the development of strategies for the resolution and/or minimisation of the problem of yellowing. The technical solutions will include innovative tanning processes, innovative finishing methods, and leather surface treatments carried out in order to provide a sensible attenuation of surface absorption of IR and UV-visible radiation.