Colourless Powdered Glass as a Drier for Red Lakes: On the Influence of Composition and Particle Size

Abstract

Colourless glass particles are observed in oil painting layers from 15 th -17 thcentury. Several historical sources mentioned the use of finely ground glass powder acting as a solid drier. To evaluate the siccative effect of the glass particles added to paint, this research focused on red lake reconstructions and followed their natural drying by means of Fourier Transform Infra-Red (FTIR) analyses. Three glasses with various sodium-potassium and manganese content in their composition were investigated.Notable differences in drying rates were observed in each of the samples, indicating a relationship between both the composition -either enriched in or without any manganese -and size of the glass particles that were added as siccatives. This FTIR approach enhances different complex mechanisms involved in the siccative effect of glass powder mixed in paint layers.