Abstract

Leather artifacts are to be found in varied archaeological and historical places (museums, storages, libraries, excavation areas). Improper environmental conditions (such as relative humidity, temperature, excess light, pollution etc.) and poor handling can affect such artifacts and lead to their increased hardness and dryness. This study aims to evaluate castor oil and polyvinylpyrrolidone (PVP) as individual materials and as a mixture at different concentrations for the lubrication of vegetabletanned leathers. Accelerated heat ageing at different temperatures was used.

The analytical techniques used for the evaluation process were digital light microscopy, scanning electron microscope (SEM), change of colour, attenuated total reflection – Fourier transform infrared spectroscopy (ATR-FTIR), and mechanical properties (tensile strength and elongation). Investigation of the surface morphology by microscopy proved that a low concentration of castor oil in the mixture gave good fibre distribution and the grain surface pattern was established for the treated and aged treated samples. The colour value and total colour difference of the treated and aged treated samples with a low concentration of castor oil were better than at a high concentration. ATR-FTIR proved that the castor oil and PVP mixture protects leather from deterioration as no free radicals were observed in the spectra. Mechanical property values proved that the use of the lubricant protected leather from accelerated heat ageing. It is recommended that, a mixture of castor oil and PVP with a ratio of 10:90 could be applied for the lubrication of dry vegetable-tanned leather artifacts.