Characterization and assessment of cleaning systems based on fatty acid methyl esters (FAMEs) for the removal of wax-based coatings from cultural heritage objects†

Abstract

This study focuses on the characterization of fatty acid methyl esters (FAMEs) and their implementation as solvents for removing beeswax and microcrystalline wax from cultural heritage materials, emphasizing their potential as sustainable alternatives to conventional solvents. FAMEs, derived from renewable sources through triglyceride transesterification, offer biodegradability and low toxicity. Additionally, the inclusion of an innovative aluminum stearate-based organogelator aims to regulate the evaporation rate of FAMEs, enhancing their application on artwork surfaces while minimizing their penetration into a substrate. Solubility tests, scanning XRF, spectrophotometry, SEM, FT-IR ATR, and contact angle measurements confirmed that all tested cleaning systems could remove up to 99% of beeswax and microcrystalline wax. Volume effectiveness calculations demonstrate that lower-polarity FAMEs, with reduced evaporation rates, require smaller solvent volumes. Restricting evaporation and solvent quantities enhances sustainability and reduces environmental and operator risks. However, adopting less volatile solvents necessitates novel application methodologies to mitigate their penetration and retention in porous artwork substrates. This research underscores FAMEs’ potential not only as solvent alternatives but also as promoters of sustainable conservation practices.