Stability of natural dyes under light emitting diode lamps

The exhibition in museum of archaeological and historical coloured textiles must keep into consideration the possible photodegradation of dyes. In the last decade, Light Emitting Diode lamps (LED) have been extensively replacing other light sources; nevertheless few studies on the influence of LEDs on degradation of natural dyes are available. In this work, the colour fading of silk samples dyed with several natural dyes (containing flavonoids and anthraquinones) and exposed to three different white LEDs is considered. The fading at the end of the exposure experiment was evaluated by measuring the variations induced by the LEDs on the colour coordinates of the samples and by investigating the variation of the concentration of the dyes by high performance liquid chromatography coupled with photo-diode array and mass spectrometric detectors. The information obtained gives an in depth picture of the fading in terms of the actual damage potential of LEDs on natural dyes and it is relevant for selecting lamps for display cases.