Historical Stained Glass Painting Techniques - Technology and preservation

Research on historical stained glass painting techniques reveals that the choice of raw materials, binders, and firing parameters significantly impacts paint adhesion and color outcomes. The study found that using zaffer as a coloring agent does not predict the final result before firing, while smalt allows for better pre-firing assessment. Sanguine red paint's outcome is highly influenced by heating rates, with gum arabic enhancing adhesion. Grisaille paints show evolving surface homogeneity over time, with variations in lead-based glass composition and colorant ratios. Corrosion studies on blue enamels indicate that the lixiviation of alkaline components can alter cobalt's color due to interactions with neighboring ions or Pb2+, potentially forming lead white. These findings, derived from a multi-analytical approach combining historical treatises, recipe reproduction, and laboratory analysis, provide new insights into the preservation and restoration of stained glass, exemplified by comparisons with fragments from Batalha Monastery and other Portuguese heritage sites.

Machado, A. S. (2018). Historical Stained Glass Painting Techniques - Technology and preservation. Unpublished. https://doi.org/10.13140/RG.2.2.25726.64329