The drying of linseed oil investigated by Fourier transform infrared spectroscopy: Historical recipes and influence of lead compounds

• FTIR-ATR is used to study the effect of lead compounds on the drying of oil films.
• Treatment with PbO makes the films more siccative with an optimal efficiency at 5%.
• A reduction of the induction time is observed but with no change in the mechanism.

Lead compounds have been commonly used since the Renaissance period to increase the drying properties of oils. This article presents new insights on the mechanisms involved: Fourier transform infrared spectroscopy (FT-IR) has been used to investigate the effects of lead oxide on the drying process of linseed oil. The changes occurring during the drying of oil and the influence generated by the use of PbO were monitored by integrating absorption bands of interest such as the ν(OH) absorption band at 3500 cm−1, and the ν(CH) in cis CCH band at 3010 cm−1. Results indicate that the addition of lead oxide accelerates the drying process and reduces the induction time (4 times with 5% PbO), without causing major changes in the mechanisms involved. An optimal amount of 5% PbO was determined, as compared to 1 and 20%. Historical recipes have been reviewed and the effect of specific oil preparation parameters such as the heating of oil while adding PbO addition and the addition of water has been investigated.

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