Lacquer Conservation techniques
18th Century Coromandel lacquer cabinet on black and gold japanned stand
Treatment included consolidation and fixing of the lifting and cupping lacquer flakes (there was a distinct alligator cracking pattern in the surface of the lacquer), and removal of previous fills that were unstable. The oil varnish was retained on the surface during the consolidation process to protect the sensitive degraded lacquer surface beneath.
It was accepted that it might not be possible to flatten the cupping lacquer flakes completely. The flakes would be fixed in position and then the background losses filled to be just below the surface of the top of the lacquer surface.
The highly discoloured upper varnish coating and associated previous retouching were removed from the surface of the lacquer to allow a harmonisation of the lacquer decoration with minimal retouching, in order to enhance the traces of original pigment which remained in the incised lacquer areas.
An X-ray of the proper left door panel revealed that numerous pins had been used to secure the Coromandel panel veneers to the pine carcase of the cabinet. The fills that hide these pins were failing in places where the oxidation of the pin has occurred. The pins were, therefore treated with an anti-oxidation agent.
The image of the bottom edge of the door also highlighted the use of a thick lead-based ground layer over the restoration section of the cabinet door.
The surface of the metal mounts was cleaned and coated with a protective layer of varnish.
A new key was made for the door.
‘Pressing’ of the cupping lacquer using shimbari technique. A frame was constructed and shimbari sticks were used to apply localised pressure to the lifting lacquer. It was not possible to flatten the surface of the lacquer completely, because of the alteration of the black lacquer and the subsequent layers of oil varnish. Severe light damage to the surface of the lacquer meant that there is a fine micro-craquelure visible, with larger cracks appearing in the centre of the flakes due to pressure from the outside cupping edges. Pressing the flakes completely flat would increase the width of these fine cracks and create new stresses on the edges of the lacquer flake.