Synthetic white pigments (white titanium and white zinc) in different binding media. Influence of environmental agents

• Preparations zinc oxide pigment is more stable than titanium oxide pigment.
• The most important impact of exposure to environmental agents is infrared radiation.
• Non destructive techniques are critical to the study of effects in the pigments.
• The techniques proved more affected with natural binders than with synthetic binders.

This work concerns the behaviour of white pigments of white titanium and white zinc in different media both of natural and synthetic binders. In addition, a study was made of the impact that time, high-energy UV radiation, heating by infrared radiation, or saturation processes of relative humidity exert on stability and chromaticity of the samples. The composition of pigments and binders as well as the time course of their samples were studied by X-ray diffraction, mass spectrometry, electron microscopy, and instrumental colour measurement. The effect of the aging, UV, and infrared exposure together with moisture saturation were found to result in losses in elasticity and cracking of the film generated by the binder, the latter two factors causing the most severe losses. The greatest variations were detected in the colorimetric study, reflecting the utility of instrumental colour measurements for these types of studies. The chromatic variations detected consist fundamentally of loss in luminosity (ΔL) and chroma (ΔC) as well as a slight yellowing tendency. In general, the samples based on natural binders were more affected that those based on synthetic products.

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