Fig. 5

SERS spectra: (a) synthetic alizarin-based lakes; (b) madder-based lakes; (c) Krapplack dunkel wash by Turm Wasserfarben Farben vs. Carminic Acid; (d) Karmin gebrannt wash by Flamuco Aquarell Farben vs. Alizarin, Purpurin and Carminic Acid; (e) Carmin fein 231 wash by Pelikan vs. Karmin n. 8 by Schoenfeld Wasserfarben; (f) Violett wash by Turm Wasserfarben vs. PV5