The silver lining: preliminary research into gold-coloured varnishes for loss compensation in two 19th C silver gilded frames

Golden varnishes appear on frames, furniture, wall hangings, leatherwork, panel paintings, mural paintings, and polychromy, and were applied to white metal gilding to imitate gold and other semi-precious materials. Despite the number of examples in cultural heritage there are few publications that discuss the ethical considerations of treating coloured silver gilded surfaces. The chromatic reintegration of gold-coloured varnishes on white metal gilding present specific material and technical challenges. In 2021 the Art Gallery of New South Wales (AGNSW) treated two identical late 19th century silver gilded frames for portraits by Joseph Backler from the Australian collection. In addition, a third portrait required the fabrication of a reproduction frame identical to the others. Conservation of the frames presented an opportunity for carrying out experiments into coloured coatings for loss compensation on silver gilding exploring applications for select conservation paints, dyes, and synthetic resins as substitutes for shellac. The results of experiments demonstrate that with the right application Liquitex Soluvar Gloss Varnish, Laropal A81 and Paraloid B72, present gloss levels and visual film forming properties comparable to shellac coatings when applied to burnished gilding. Additional tests with various dye colours illustrate that Orasol ® dye mixtures in colours Yellow 2GLN, Yellow 2RL, and Brown 2GL are reliable colour imitations for traditional gold-coloured varnishes. Although this research is preliminary, it may inform the selection and application of appropriate retouching materials for compensating losses to burnished silver leaf and golden varnishes in gilding conservation.