Citation: Veiga, T.; Moro, A.J.; Nabais, P.; Vilarigues, M.; Otero, V. A First Approach to the Study of Winsor & Newton’s 19th-Century Manufacture of Madder Red Lake Pigments. Heritage 2023, 6, 3606–3621. https://doi.org/10.3390/ heritage6040192 Academic Editors: Marei Hacke, Sara Norrehed, Joanne Dyer, Jo Kirby, Art Proaño Gaibor, Ilaria Degano, Zvi Koren and Sandström Edith Received: 7 March 2023 Revised: 7 April 2023 Accepted: 8 April 2023 Published: 12 April 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). heritage Article A First Approach to the Study of Winsor & Newton’s 19th-Century Manufacture of Madder Red Lake Pigments Tiago Veiga 1,2 , Artur J. Moro 3 , Paula Nabais 1 ,Márcia Vilarigues 2 and Vanessa Otero 1,2, * 1 Department of Conservation and Restoration and LAQV-REQUIMTE Research Unit, NOVA School of Sciences and Technology (FCT NOVA), 2829-516 Caparica, Portugal 2 Department of Conservation and Restoration and VICARTE Research Unit, NOVA School of Sciences and Technology (FCT NOVA), 2829-516 Caparica, Portugal 3 Department of Chemistry and LAQV-REQUIMTE Research Unit, NOVA School of Sciences and Technology (FCT NOVA), 2829-516 Caparica, Portugal * Correspondence: van_otero@fct.unl.pt Abstract: This paper focuses on the first investigation of the 19th-century manufacture of red lake pigments obtained from madder by Winsor & Newton (W&N), prominent artists’ colourman at that time. The first approach to their manufacture was carried out by studying the madder entries of the company’s book P1, found in the W&N 19th Century Archive Database. Eleven production records were discovered under names such as Rose Madder, Madder Carmine, Madder Lake and Madder Rose. Three main methods of synthesis were identified and reproduced, revealing three main steps: washing of the madder roots (Rubia tinctorum L.); extraction in acid media and complexation with Al 3+ using alum; and precipitation by the addition of salts such as ammonium carbonate and sodium borate. The syntheses were followed by UV-VIS spectroscopy, and the pigments were further characterised by colourimetry, Energy-Dispersive X-Ray Fluorescence Spectrometry (XRF), Fourier Transform Infrared Spectroscopy (FTIR) and High-Performance Liquid Chromatography-Diode Array Detector (HPLC-DAD). They all exhibited a rose hue in a highly insoluble aluminate matrix. Although the dye extraction was incomplete, alizarin, purpurin and pseudopurpurin were identified. An analytical comparison with a Rose Madder 19th-century oil paint tube was also performed by micro-FTIR and microspectrofluorimetry. This work intends to be foundational to a systematic study of the W&N’s 19th-century madder colours aiming to contribute new knowledge towards their identification and preservation in heritage objects. Keywords: madder; 19th-century manufacture; Winsor & Newton; multi-analytical characterisation; heritage preservation 1. Introduction Since antiquity, madder has been one of the most important sources of red colours. Used as dyes and pigments, these colours have been found in treasured artworks [1–4]. The first reference to its use as a dye dates back to the seventh century BC found in a neo-Babylonian tablet kept at the British Museum. The earliest it has been identified as a pigment was also in ancient objects such as Cypriot pottery of the 8th–7th century BC [1,3]. Madder colours are extracted from the roots of plants from the Rubiaceae family, but the most relevant species for dyeing are Rubia peregrina L. (wild plants) and Rubia tinctorum L. (cultivated plants), the latter being the most used for dyeing in western Europe from the Middle Ages to the 19th century [1–7]. Their composition differs quantitatively but qualitatively is based on anthraquinone compounds in the form of glycosides and respective aglycones (Figure 1). The main anthraquinones responsible for the colour are alizarin (1,2- dihydroxyanthraquinone), followed by purpurin (1,2,4-trihydroxyanthraquinone) and pseudopurpurin (1,3,4-trihydroxyanthraquinone-2-carboxylic acid) (Figure 1)[1–3]. Heritage 2023, 6, 3606–3621. https://doi.org/10.3390/heritage6040192 https://www.mdpi.com/journal/heritage