lac dye

Ingredients

sticklac, lead white, vermilion, gypsum, calcium carbonate

Preparation Steps

Original Recipe Text

Pink colours were obtained by admixing lac with lead white or with lead white and vermilion (p. 90). In the Alcobaça scriptorium, lac was frequently mixed with gypsum in significant proportions as a filler to create opaque paints (p. 90). Dark reds were obtained by admixing lac with vermilion, a practice characteristic of Santa Cruz manuscripts (p. 90). To achieve a glassy appearance, paints were formulated without fillers but with the help of proteinaceous binders like parchment glue and/or egg white (p. 90). The incorporation of resin components via heating above 60°C or using basic extraction solutions (pH > 8) promotes the dissolution of shellac constituents into the final paint (p. 94).

Evidence

"In a previous study, analytical techniques identified lac dye in dark reds from Portuguese illuminations by comparison with historical reproductions (Castro et al. 2014). Lac dye was produced mainly in southern and southeastern Asia... its main components are laccaic acids A and B; laccaic acids C, D and E also found in minor quantities... also contains erythrolaccin, which is responsible for the yellowish-orange hue that characterises the resin."

Remarks

In the Alcobaça scriptorium, gypsum was found in significant proportions as a filler, whereas in Santa Cruz and Lorvão, calcium carbonate was more prevalent (p. 90). The research highlights that lac dye confirmed the existence of an Arabic and Jewish trade network in Portugal during the Romanesque period (p. 90). Analytical results from microfluorimetry display two bands with maxima at 526 and 562 nm, typical for lac reproductions with alum (p. 94).