Test Methods for Chemical Analysis of Cuprous Oxide and Copper Pigments

2019 ◽  
Author(s):  
1959 ◽  
Vol 39 (1-2) ◽  
pp. 87-90 ◽  
Author(s):  
H. J. Plenderleith ◽  
H. Maryon

Summary1. An ideal opportunity for making a detailed comparative study of ten of the royal effigies from Westminster Abbey was presented by their temporary assembly for cleaning purposes in the Undercroft.2. It was possible to make a special examination of the backs of the figures as well as the parts usually exposed, and in the course of study two distinct methods of metal-casting were recognized, (a) a bell-founding technique similar to that described by Theophilus, and (b) a wax-cast technique.3. Mercury, or fire-gilding, had been applied in all cases. In one instance chemical analysis of a silvery smear in the folds of the drapery showed it to be due to gold amalgam. There was no corrosion of the surrounding metal.4. The colour of the gold surface was occasionally greenish, indicating that a base gold had been employed in making the amalgam. In other cases an artificial richness had been imparted, doubtless with the lapse of time, by the red cuprous oxide of the underlying base metal shining through the thin surface film.5. Of the two wooden effigies examined, that of William de Valence showed more points of interest. The question as to whether there was indeed champlevé work in the enamelled ornament had to be left open, as it was considered impossible to answer without in a measure undoing something of the recent work of the restorer.


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