The magnificent appearance of this portrait owes much to the rich red colour of the sitter’s costume. Analysis of a tiny sample suggests that two layers of transparent red lake glaze were used on top of an opaque layer of red pigment to create the intense red of the sitter’s gown. In the lower glaze is a madder lake, while the upper glaze contains high levels of kermes.

The expense and rarity of kermes explains why it is reserved only for the final paint layer. In order to be used for painting, kermes was usually extracted from offcuts of dyed silk. So the same precious pigment could have been used to dye the actual clothes the sitter wears, and to represent those beautifully recreated in his portrait.

Panel analysis

This painting is composed of four oak boards, which have been sourced to the eastern Baltic around modern-day Poland. Since oak from this region was the high-quality wood of choice during the sixteenth century and could be bought across Europe this identification does not provide a definitive confirmation of the painting’s country of origin.

Dendrochronology – scientific analysis of the sequences of tree rings in the panels – suggests that the wood used was felled between c.1527 and c.1543. On the basis of panel analysis alone, a latest date for the painting is difficult to establish with certainty, although the wood is unlikely to have been left unused for decades after felling.

Chalk analysis

In order to provide a smooth painting surface, a ground layer is applied onto the wooden panel. In northern Europe chalk forms a key constituent of this layer and the tiny nannoplankton from which it is formed can be examined to identify where the chalk might have been mined – this can help establish where the painting could have been produced.

Several marker species of nannoplankton were identified in a small sample taken from this painting. Based on which chalk quarries were active during the sixteenth century, this analysis suggests that the chalk could have been sourced from Kent and Norfolk in England, and northern Europe including Germany, Poland and parts of southern Russia.

Infrared reflectography

Infrared reflectography was used to detect underdrawing beneath the paint. While the artist of this portrait remains unknown, the underdrawing could provide a clue to the authorship, technique and painting process. In several places the underdrawing diverges significantly from the final painting, for example two garters which were originally intended at the knees and were then completed in the paint layers were ultimately suppressed by the artist. Perhaps it was felt that the left one would have diminished the impact of the large tassel hanging from the dagger, which has been given great prominence. Alternatively, the removal of the garters may represent a change in fashion.