Picture frames and gilded objects are often more complex than they first appear to be and can be made up from a wide variety of materials. In the UK, the wooden substrate of picture and mirror frames is often a species of pine but oak, lime and a spectrum of other hard and softwoods are also found. Generally, ornament in relief is made from either:
The materials and techniques of a gilded finish can vary enormously from one piece to another; note that other varieties of metal leaf than gold may be used. The base for the gilding is likely to consist of a hard white coating of chalky appearance - commonly called ‘gesso’ - covered with one of two finishes:
Changes in the environment can cause movement of timber and applied finishes, resulting in the opening up of structural joints and cracking of the finish. The appearance of cracks in a gilded surface around the mitred corners of a picture frame may not necessarily be a real cause for concern, but should be carefully monitored and assessed, as major opening or loose joints can put frame and picture at risk.
The appearance of cracks in the gilded finish is a common symptom of ageing and not normally a cause for concern. If however the gold and gesso layer is lifting, loose, or falling flakes appear, this may indicate that the gilding layers are delaminating from the substrate. Cracks in the applied composition ornament are also a common symptom of age-related shrinkage, but be aware that this could lead eventually to detachment of the ornament.
The common furniture beetle (anobium punctatum) is the most frequent cause of pest damage to gilded objects with a wooden substrate, evidenced by 1-3 mm diameter flight holes in the surface of the item. The extent of damage underlying the finish will vary, but may be extensive enough to weaken the object's structure. Inactive woodworm may cause concern structurally and aesthetically; active woodworm can and should be treated immediately. Wood-rots and moulds on the wood or gilding can also cause staining and structural damage where the item has been stored in or subject to wet or damp conditions.
Frames and other gilded items are subject to the usual degree of wear and tear resulting from life in a domestic or gallery environment – examples are surface damage from minor scratches, dents and abrasion, or staining from accidental contact with water or other solvents. Gold leaf wear is apparent when the clay bole layer (often a shade of red) begins to show through the worn leaf on the most prominent parts of the object. It is also common to see gilded surfaces stained and damaged by inappropriate cleaning agents used in the course of attempts at repair by amateurs.
A common result of amateur repair is ‘gold’ or ‘bronze’ paint applied to a gilded finish in order to cover damages or to brighten or even tone down the gilding. The paints are made with non-gold metal powders which can oxidise and change to brown or green; they can be identified as a muddy, slightly granular, streaky coating against the bright sheen of real gold leaf. Beware however that in some cases, non-gold metal leaf and ‘bronze’ paint may be part of the intended original finish of an object.
It is a good idea to monitor an object’s condition at regular intervals. This can be as simple a process as writing down the position of any areas or signs of damage (such as new flight holes) on an annual basis.
Keep moving or handling of gilded objects to a minimum. If moving cannot be avoided, you should wear vinyl or latex snug-fitting gloves, as oil or moisture from the hand will damage the finish on a frame. Make sure there are enough people to lift it slowly and safely if it is heavy, preferably lifting underneath a frame’s lower member to avoid putting too much pressure on the joints. Make sure you have a space prepared to take the frame to before you start. If you are moving smaller objects, they should still be moved one at a time.
Keep cleaning to a minimum; dusting once per year is enough as the action will gradually wear away the gilded surface. Even the dust itself being moved off will cause some abrasion, so a very soft-haired brush should be used. The brush's metal ferrule should be wrapped in tape to protect the object against accidental knocking. Dust can be collected using a vacuum cleaner set on minimal suction, lifting the dust with a small nozzle covered with a piece of gauze secured with an elastic band. This ensures that no pieces of loose ornament are lost. Care should be taken not to touch the object with the nozzle.
Store and display gilded objects away from direct heat sources such as radiators or fires. Likewise, avoid placing them against or near a wall or surface that has - or may be at risk from - damp or leaks. Gilded objects are fragile and should be displayed away from major thoroughfares or anywhere where they may be vulnerable to knocks, such as behind doors or directly behind the backs of chairs. Always make sure objects are properly secured to the wall or relevant area.
Bear in mind that an object can be irreversibly changed and its historical and/or monetary value damaged by ill-advised interventive treatment. Even taking a picture out of its frame yourself or trying to carry out more than dusting to clean a frame can result in serious damage. It is always advisable to seek professional advice. A conservator can help by:
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© Icon, the Institute of Conservation 2011.
This article offers general guidance and is not intended to be a substitute for the professional advice of an accredited conservator. The views expressed are those of the author or authors, and do not necessarily represent the views of the Institute of Conservation. The Institute of Conservation would like to acknowledge use of the MGC publication 'Ours for Keeps' in the preparation of this text. The Institute of Conservation and its partners accept no liability for any loss or damage which may arise if this guidance is followed.
The Institute of Conservation would like to acknowledge the support of The Royal Commission for the Exhibition of 1851 in the production of this guidance information. Further information on The Royal Commission for the Exhibition of 1851 and its work is available at www.royalcommission1851.org.uk.