New insights into the materials of fifteenth- and sixteenth-century Netherlandish paintings in the National Gallery, London

Heritage Science

Table 1 Quantitative analysis of the colourless powdered glass additive in five of the sixteenth-century Netherlandish paintings in the National Gallery, London (expressed as weight percent oxide)

Artist, painting title, date	Areas with powdered glass in the paint	Glass type	Na₂O	MgO	Al₂O₃	SiO₂	P₂O₅	SO₃	K₂O	CaO	TiO₂	MnO	FeO
Albert Cornelis, The Magdalen in a Landscape (NG2585), c.1520	Pink robe of the angel, with lead white, fluorite and red lake: two types of glass	Wood ash–lime (high lime–low potash)	2.8	4.0	2.2	56.0	3.6	0.7	4.8	24.2	0.2	0.6	0.5
		Wood ash	2.2	5.7	2.0	58.6	4.0	0.8	7.8	17.0	0.2	0.7	0.5
Attributed to Jan Mostaert, The Head of Saint John the Baptist, with Mourning Angels (NG1080), probably 1520s	Red paint beneath the oblong area painted with figures, with vermilion	Wood ash–lime (high lime–low potash)	3.6	3.7	1.9	54.7	4.4	6.1	3.5	20.0	0.4	1.0	0.6
Lucas Van Leyden, A Man aged 38 (NG3604), about 1521	Purple robe, in underpaint, with red lake, azurite, lead white, red earth, and in the final glazes with red lake: three types of glass	Soda ash	11.6	2.0	1.2	66.6	2.0	1.8	2.6	9.1	0.5	0.8	0.3
		Wood ash	2.1	4.9	1.9	57.7	3.8	1.4	9.6	16.4	0.2	0.7	0.6
		Wood ash–lime (high lime–low potash)	1.5	4.2	1.8	56.9	3.9	1.9	5.8	21.6	0.2	1.0	0.5
Workshop of the Master of the Holy Blood, A Young Man Praying (NG1063), probably 1525–30	Black coat, with black and a little lead white	Wood ash	0.5	3.9	2.0	60.6	1.9	3.3	7.2	18.9	0.2	0.7	0.5
Catharina van Hemessen, Portrait of a Woman (NG4732), 1551	Green background, in underpaint (with lead white, black, lead–tin yellow); two types of glass	Wood ash–lime (high lime–low potash)	2.8	2.9	3.3	59.4	3.0	0.8	3.9	21.8	0.4	0.5	0.6
		Wood ash	2.1	4.3	2.1	54.5	4.2	5.1	10.8	14.2	0.2	0.7	0.9