Analytical study of modern paint layers on metal knight shields: The use and effect of Titanium white

• Investigation of the role of titanium white pigments in alkyd paint.
• Characterization of three different industrial coat systems on metal knight shields.
• Identification of lead corrosion products in the metal/paint interface causing paint delamination.
• Degradation of exposed pigmented paint layers containing anatase.
• Influence of the climatic conditions on the stability of the knight shields.

Painted metal knight shields of the Order of the Elephant produced during the last part of the 20th century are characterized by a striking variety in their conservation state. Three different coat systems were identified and investigated by Fourier transform infrared microscopy (μ-FTIR), micro-Raman spectroscopy (MRS), scanning electron microscopy–Energy dispersive X-ray spectroscopy (SEM–EDX) and Thermally assisted hydrolysis and methylation-gas chromatography–mass Spectrometry (THM–GC–MS). Chalking of the white paint layer on the first group of knight shields displayed in the window niches was found to be related to the use of titanium white of the anatase type. A pristine condition of the second group could be attributed to priming of the lead rich metal support with a zinc potassium chromate based primer and the use of mainly stable white pigments in the top coat. Severe delamination of the paint layer of the third group was caused by the formation of lead corrosion products between the paint layer and the metal support. The results are discussed in relation to the climatic conditions as well as the historical context of contemporary paint production and availability in Denmark.

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