16th Century Restoration
The Henry III charter is an unique experience to observe a historical restoration that was undertaken at the beginning of the 16th century, (Birch, Walter de Gray. 1911, xix).
The restoration.
It can be observed that the central figure from the original wax seal remains. It has been consolidated with the new orange wax and would have been carried out as part of the sixteenth century restoration.
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X-ray imaging.
We can observe the seal in the silver frame, which circumnavigates the outer edge of the seal with two strips of metal crossing in the middle to form an “X”.
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The metal cage observed through X-ray. 10x10 kvp
Purest gold!
Through XRF analysis and inspection under a microscope, we have discovered that the silver frame is made of a silver and copper alloy (sterling silver), and was originally gold plated! The surviving gold plating can be observed in the grooves of the silver frame.
It was likely to have been traditionally gilded through the application of gold leaf and an animal glue “sizing” or would have been burnished onto the silver by rubbing it with a burnishing tool. (Oddy, A. 1995)
Gold observed under 200x magnification.
The RTI tool can be found on Â
Reflectance Transformation Imaging (RTI).
Through the use of Reflectance Transformation Imaging (RTI) we can reveal surface information that is invisible under normal examination. RTI is a photographic method that captures multiple photographs of an object where the image is taken with light projected from different directions (raking light). The varying highlights and shadows enable fine details of the surface to be visible (Cultural Heritage Imaging, 2024).
Under close inspection of the raking light images, we can identify tool marks in the restoration wax (orange). These tool marks indicate that the new wax was pared back using a scraping tool after it had cooled down. The tool used appears to have had a straight sharp edge that has formed ridges in the wax.
200x magnification.
Evidence of 'wax bloom' deposits, 200x magnification.
The white layer is considered to be aesthetically unacceptable as it makes the image illegible. In addition, the compounds that form the efflorescence are regarded as the plasticisers of the beeswax, and their depletion causes the wax seal to become brittle (Bartl, B. et al 2012). In a brittle and friable state, the wax seal is susceptible to damage through handling and physical forces.
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To the right is an example of efflorescence on a surviving King Henry III seal.
Why did it need restoring?
The wax seal had deteriorated, and was in need of restoration to prevent further losses. Through investigation, it is possible to determine the cause for the wax's deterioration.
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Under microscopy analysis, we can identify a 'wax bloom' on the green wax. The 'wax bloom', otherwise known as efflorescence, is used to describe either a white crystallin layer or clusters of crystals.
The efflorescence on the surface of the beeswax pendant seal from the 13th century © Bartl, B. et al, 2013
