LITHOL RED SALTS: CHARACTERIZATION AND DETERIORATION

Lithol Red salts are one of the commonest 20th century redsynthetic organic pigments. We characterized the sodium,barium, and calcium Lithol Red salts with nuclear magneticresonance spectroscopy, powder X-ray diffraction, Fouriertransform infrared spectroscopy, Raman spectroscopy, andlaser desorption ionization mass spectrometry. The sodiumand calcium salts were synthesized and compared to commercialsamples. The single cr ystal structure of calciumLithol Red is reported here for the first time. Light agingexperiments show that the neat powder is very lightfast butthat the pigment has poor light stability within paint systems.This suggests that the binding medium facilitates thephotodegradation of the pigment for the latter case.