The research focused on investigating orange patinas found on limestone surfaces at the Batalha Monastery. The study aimed to determine the composition, formation, and degradation patterns of these patinas. Different compositions and appearances were observed on an ornament and a window tracery, suggesting varied formation pathways.
The orange patina on the ornament appeared to be intentionally applied, containing gypsum and hematite. In contrast, the orange patina on the window tracery seemed to have formed naturally, possibly due to atmospheric pollutants or bacterial activity.
Comparisons were made with previous research, indicating similarities with a “scialbatura” nature. The samples analysed were from outdoor fragments exposed to environmental elements like sun and rain. The presence of calcium oxalate and other mineral grains contributed to the distinctive coloration of the patinas. The study highlighted the possible interaction between the limestone substrate, orange patinas, and the urban environment surrounding the Monastery.
Overall, the research shed light on the complex nature of these orange patinas, showcasing differences in composition, appearance, and decay patterns between the two samples. The ornament’s orange layer followed the object’s geometrical shape, while the window tracery’s patina was closely adherent to the limestone substrate. Decay patterns also differed, with flaking observed on the ornament and higher halite content detected on the peeled-off lamination.
These findings provide valuable insights into the interaction between environmental pollution and cultural heritage, emphasising the importance of understanding the factors influencing the degradation of historical structures.
