Johan G. Neevel’s research while affiliated with Rijksdienst voor Cultureel Erfgoed and other places

Bright violet-coloured aniline dyes were developed and produced from the late 19th century onwards. Primarily used for dyeing of textiles, they were also employed in inks for letters and drawings. The in- dustrial production of these dyes comprised numerous companies in Germany, France and England and concurrent chemical synthesis methods rapidly evolved. ‘Methyl violet’, also known as ‘Violet de Paris’, is an example of an aniline dye that made a large impact in Europe and was widely used. This study aims to provide insight into the composition of historical ‘Methyl violet’ dyes to gain a better under- standing of the formulation of past inks, their degradation and to support colour reconstruction of old drawings and manuscripts. Thirty-nine ‘Methyl violet’ reference samples, dating from the late 19th century until the 1930′ s, originating from leading dye producers in Europe, were analysed. UHPLC-PDA-HRMS was applied for the identification of the dye compounds. It was revealed that a significant part (ca. 35%) contained not only methylated, but also benzylated pararosanilines. Although benzylated compounds are mentioned in historical sources as ‘Methyl violet’, ‘Violet the Paris’, and ‘Methyl violet 6B’, they have only once been reported in modern literature and are now elucidated in detail for the first time. The rela- tive amount of highly substituted pararosaniline increases when benzylation is performed resulting in an overall “bluer” dye mixture. The benzylated Methyl violets were mostly found in ‘Methyl violet 6B’ sam- ples, but not exclusively. This exploration of the composition of a large number of historical ‘Methyl violet’ samples highlights the complexity and compositional variety of early synthetic dyestuff productions and the importance of large-scale studies of historical references.

This paper introduces a new set-up for the determination of colour change on cultural heritage objects, referred to herein as a stereo-microfading tester. The system uses high quality optics through the implementation of a stereo-microscope as its central element. This technology enables new developments such as incorporation of high quality imaging systems, and separation of fading and colour measurement processes. This paper describes this new micro-fading set-up and evaluates its performance against traditional devices based on the measurement of blue wool standards. The results show a correlation between the fading performance obtained on different devices while highlighting a significant variability inherent to the blue wool samples

The Dutch paint manufacturer Talens & Co (now Royal Talens) started the production of the brand Rembrandt Olieverven in 1904 in Apeldoorn and much of the company’s historical archive still remains.

Within a research project focusing on the dramatic colour changes in Van Gogh's pen-and-ink drawings, interpretation of the analytical results requires a thorough understanding of late 19th-century ink manufacturing. Our laboratory had the unique opportunity to acquire a set of 90 historic ink bottles still containing ink. In this study, their chemical characterisation and the interpretation of these findings within the framework of ink manufacturing history are reported.