Precious metals have been used since antiquity and across many cultures in the making of valuable art and artefacts. However due to their high cost these were commonly beaten into thin films or foils and applied to a solid base such as timber to give the appearance of solid gold.
The conservation of gilded objects deals with a range of decorative arts items, artworks and artefacts that use thin film metal foils and metal powders (traditionally gold, silver, brass and platinum) over timber substrates. The foil, or leaf, can be applied with a range adhesives including water, oil, resins, and modern materials such as epoxies and acrylics.
But not all that glistens is gold. In the nineteenth century, bronze and other metal powders were introduced, whilst the twentieth century saw the development of titanium oxide pigments used in waxes, acrylic and gouache mediums.
Gilded objects conservation commonly deals with the preservation and treatment of furniture, frames, religious icons and statues. In addition, works on both paper and canvas supports also incorporate gilded elements in its borders, backgrounds and text.
Common types of deterioration
Due to the thin nature of the metal leaf used in gilding, wear through handling and usage can cause loss to the gilded surface, revealing the underlying layers. Many decorative items are highly functional and this type of wear is seen on areas which are handled, such as armrests and footrests.
Water-gilded surfaces are highly susceptible to wear, and gold surfaces can be accidentially removed with a damp cloth or sprays (much to the horror of many a cleaner!)
Where metals other than gold (which does not corrode), have been used for gilding, the surface may show signs of corrosion and discolouration over time. This is especially visible in instances where bronze paint has been used to re-coat worn or damaged gilded surfaces. While gold retains its bright lustre for centuries, bronze paints darkens within a few years.
Gilded surfaces are made up of several layers including the metal leaf, adhesive layers, the underlying solid timber substrate and protective surface coating. Each of these layers responds differently to changes in temperature and humidity that can cause cracking and flaking across layers. Timber structure susceptible to breakage, insect and pest damage, and cracking and splitting from environmental changes.
Conservators working with decorative arts item try to minimise damage in the first instance by controlling temperature fluctuations that can cause cracking across the different materials.
Where damage is present, conservators document the damage for reference and undertake materials analysis and testing, to ensure that the treatment method and materials used are compatible.
Treatments commonly focus on stabilising the underlying timber structure and surface cracks or reinstating losses to the timber structure and/or gilded surface layers and protective coatings.
Conservation or restoration?
In comparison to restoration processes that sometimes involve stripping and re-finishing of surfaces or replacement of whole timber components, for example those with borer damage, conservation tries to retain as much of the original material as possible for aesthetic, value and documentary reasons. The level of intervention will depend on the context of display.
For example, a gilded chair in a gallery or museum context is likely to be treated as a non-functioning object with originality of materials and the history of use in mind. In contrast, the same chair might need structural treatment or the application of a protective surface coating if it is still to be used as a working chair.
AICCM has a Special Interest Group for those interested in the conservation of gilded objects. Join this group, contribute to its activities, or speak to a specialist conservator.