The effect of new LED lighting systems on the colour of modern paints

Abstract

This research focuses on the investigation of the effect of a new light emitting diode (LED)-lighting system which reproduces indoor museum conditions, on some self-made art paint colours (acrylic-, alkyd-, and linseed oil-based paints) often used in modern-contemporary art. A halogen lamp representing a traditional light source for museum lighting was also considered. Lighting-set-up and lighting optimization parameters were considered while Ultraviolet/Visible/Near Infrared (UV/Vis/NIR) spectrophotometry was used for investigating the colour change of the paint samples. Univariate analyses allowed determining the highest effect of the lighting systems on the linseed oil binder and ultramarine blue PB29 mixture upon ageing, according to the highest total colour change ΔE*ab. In a more specific and detailed way, variance analyses not only demonstrated the strong correlation between the type of binder and pigment used for the paint samples with the colour variation, but also showed that the short-wavelength blue LEDs influenced the change along the yellow–blue b* axis of the yellow and blue samples, whereas the halogen lamp mostly had an impact towards the red–green a* axis of mostly the green specimens.

A Multi-Analytical Approach for Studying the Effect of New LED Lighting Systems on Modern Paints: Chemical Stability Investigations

“…Divided in two parts, this research presents important information obtained through a series of experiments for the investigation of the damaging effects of a new developed LED lighting on modern paint materials. Whereas in the first part of our research [30], a study of the effects of two LED light systems and a halogen lamp on the colour stability of some self-made paint samples by ultraviolet/visible/near infrared (UV/Vis/NIR) was presented, this current work, as the second part, aims to determine any chemical changes in the considered paint samples possibly caused by the exposure to the lighting systems and to find a correlation with the colour changes observed and determined by UV/Vis/NIR measurements [30]. For this purpose, and as part of the developed multi-analytical approach, pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), thermally assisted hydrolysis and methylation of GC/MS (THM-GC/MS), micro-attenuated total reflection of Fourier transform infrared (µ-ATR-FTIR), and µ-Raman spectroscopies were used.…”

“…A detailed description of the mock-ups and of the three main lighting systems used, including set up and the selected parameters, is reported elsewhere [30]. Summarizing, "2-component self-made paint" mock-ups were prepared by mixing inorganic pigments powders (Kremer Pigmente, Aichstetten, Germany) with an alkyd (Medium 4-Lukas, Düsseldorf, Germany), acrylic (Plextol D498-Kremer Pigmente, Aichstetten, Germany) and linseed oil (Kremer Pigmente, Aichstetten, Germany) binding media (BM) in different ratio (P/BM) depending on the consistency of the paint achieved.…”

“…In order to investigate whether possible chemical changes occurred on the paint surface during the exposure to the three different types of illuminant, particularly those with a colour change evidenced by UV/Vis/NIR measurements [30], the samples were analysed before (unaged samples) and after each exposure cycle (1240, 2400, 3300, and 5000 h) by means of µ-ATR-FTIR and µ-Raman spectroscopies. Additionally, bulk of the acrylic mock-ups were analysed by Py-GC/MS before and after 2400 and 5000 h of ageing, the harmless effect of while bulks of the unaged and 2400-and 5000-h aged alkyd and linseed oil specimens were investigated by THM-GC/MS.…”

“…On the other hand, samples for Py-GCMS and THM-GC/MS were taken from areas close to those measurement' spots. The detection of the colour change of the specimens by UV/Vis/NIR was calculated by using the total colour difference values (∆E*) according to the CIE 1976 (∆E* ab ), which has been summarized from [30] and reported here in Table 1 for finding a possible correlation between chemical and colour changes in the investigated samples. The analytical techniques used for developing a proper multi-analytical approach are distinguished according to their applications and described in detail hereafter.…”

“…Additionally, LED-based lighting systems and their effects on the stability of modern paints used in modern-contemporary art still needs to be studied in order to determine if they can be potentially detrimental to the different types of components usually included in a paint system, for example by fast photo-oxidative deterioration. Although the number of LED ageing studies on artistic materials has been increasing in the last years and particularly on paints [21][22][23][24][25][26][27][28][29], comprehensive research finalized to the investigation of the chemical stability of the irradiated paint materials is still lacking.…”