Gilding on plate armour
Many high quality steel armours were highly decorated with precious metal coatings. For this armour made in the royal workshops in Greenwich around 1610, over-enthusiastic cleaning over many years has removed almost all of the original gilding.
Not only is the detection of gilding important for understanding the aesthetics of the armour, but its application method may have influenced the metallurgical processes involved in its manufacture: How was the process combined with the heat treatment regimes carried out in the Greenwich workshops at this time?
Results of analysis
Qualitative XRF analysis produced a spectrum that could be interpreted visually. Gold was seen as a series of peaks, whilst mercury appeared as a “shoulder” on two of these peaks. The presence of mercury tells us that the gold was applied by amalgam (fire) gilding. The small peak for copper derives from the use of a thin wash of this metal to provide a stronger bond between iron and gold.
This functional armour was made at a date when high quality armour was heat treated by quenching and tempering to enhance their protective qualities. Because fire-gilding is also a high temperature process, it would appear that this was carried out simultaneously with the tempering to obtain an armour that is both highly decorative and offered a high degree of protection to the wearer.
The results of this research, as well as informing the Collections Care Department, have been included in a number of specialist and public presentations. One particular benefit was that it enables other, non-authentic gilding, to be identified as later restoration.