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Table 1 A total of 70 emission and 70 excitation spectra on 37 lac dye paints were collected from 17 illuminated manuscripts produced in Portuguese monasteries (12th–13th c.). Based on their spectral features and intensity these spectra were assembled in 4 groups, Lac 1 to 4

From: Organic colorants based on lac dye and brazilwood as markers for a chronology and geography of medieval scriptoria: a chemometrics approach

  Lac 1 Lac 2 Lac 3 Lac 4
Excitation maxima 473 nm
Band at 430 nm
535–555 nm 525 nm
sh 500 nm (resin chromophores)
sh 550–555 nm
554 nm
Intensity
 Max 4.2 × 105 4.8 × 105 6.5 × 105 1.0 × 106
 Min 1.3 × 105 2.6 × 105 2.2 × 105 4.6 × 105
Emission maxima 588–593 nm
sh 562 nm sh 615 nm
585–590 nm
sh 563 nm
sh 610–616 nm
585–590 nm
sh 610–616 nm
600–610 nm
592–594 nm sh 610 nm
Intensity
 Max 8.1 × 104 9.2 × 104 1.3 × 105 9.3 × 104
 Min 2.1 × 104 3.4 × 104 2.0 × 104 3.6 × 104
  1. The values for the emission and excitation maxima are in italics
  2. sh shoulder