Unravelling the colour palette The reconstruction and analysis of synthetic colour stains

Over recent years the Cultural Heritage Agency of the Netherlands (Rijksdienst voor het Cultureel Erfgoed) has conducted several investigations into early synthetic dyes that are used as wood stains. Their poor light fastness means that these dyes are often severely faded. Nevertheless it is usually possible to find parts of a piece of furniture where the original colour is still visible, for example in places that are covered and therefore shielded from light. Against this background a 2007 study looked at 19th century marquetry used on 17th century furniture.2 These appeared to have been stained primarily with synthetic dyes, detectable particularly on the rear of the inlay work. What was striking, however, was the difficulty encountered in identifying the dyes, even in areas which were not heavily faded. The reason for this was unclear; was the concentration of the dyes applied to the wood low, or was the method used to extract the dyes from the wood unsuitable? Pronouncing judgements about the original colour also proved troublesome, while that is often the primary reason to conduct colour research. It is not only the characteristics of the dye which play a role in determining the original colour of a piece of furniture: the colour of the wood, the concentration of the dye, additives included in the recipe for the stain and other factors also need to be taken into account. That is why a research program was launched involving reconstructions: veneers were coloured with a representative selection of dyes. Studying and following historical recipes and varying various parameters allowed us to make more informed judgements about the original colours. Subsequently, these reconstructions were also used to optimise the analytical method. The results of this research are described in this
article.