THE CARE OF ANTIQUE FURNITURE

By John W. L. Kitchen MBE

Retired Head of Conservation, Furniture and Woodwork at The Victoria and Albert Museum

We cannot live in comfort and apply the most stringent principles of Conservation to our antique furniture. We can and should be knowledgeable of the damaging elements that, if ignored, will hasten the destruction of the organic and some inorganic materials from which our furniture may be made. The natural causes of deterioration can be broadly divided into two groups: Environmental Conditions & Biological Conditions. To these must be added a third group: Human Intervention.

Environmental Conditions

Humidity will vary between "Too High" at a Relative Humidity (RH) of 70% to "Too Low" at 30% RH. It is important to minimize the fluctuations as much as possible because with every change all the wooden members, that together make a piece of furniture, will move independently. Wood expands in its width and thickness (across the grain) but makes no significant adjustment in its length (along the grain). Rapid daily changes are very much less of a concern than are those created seasonally, especially since the advent of central heating.

Museum and other owners of large collections of furniture strive, with the aid of humidity control machines, to maintain an even RH. People in the private sector should also try to emulate the "professionals", but only if the quality of their antiques warrants both the expense and trouble of maintenance that humidifiers and dehumidifiers demand. In periods of extreme dryness wet cloth draped over radiators or purpose made "humidity wicks" hung on them, may make a modicum of difference. It would be more effective to lower the background temperature and use local heat only when necessary.

Cold Outside Warm Inside = Dry Conditions Shrinking timber causing opening-up of the joints, warping, splitting & cracking and torn veneers.

Warm Outside Cool or Warm Inside = Damp Conditions Expanding timber causing Warping and Compression Stresses - internal damage to the cell structure of the wood, which adds, in time, to additional shrinkage.

A warm and damp environment accelerates chemical action. Materials which become chemically unbalanced, such as leather (particularly of the late nineteenth and early twentieth centuries), paper and textiles are at risk. A damp environment will cause dust-covered metals to be severely damaged. Marble too can become stained from dust in similar conditions. Bronze mounts are susceptible to Bronze Disease, the appearance of blue/green copper on its surface, in a warm damp acid environment.

All light and daylight in particular, contains Ultraviolet light - the wavelength of light that is most damaging to colours of both dyed and natural woods and textiles. Direct sunlight also heats up the parts of objects it falls upon. This warm dry microclimate is evidenced in damage to surface coatings, veneers and the underlying adhesive. The exposure of Oriental Lacquer to daylight should be kept to a minimum, while the whiteness of ivory may be enhanced by shaded daylight.

Biological Conditions

The common furniture beetle (Anobium punctatum) is, or has been, more responsible for rendering furniture unsafe than perhaps any other factor. Fortunately today, eradication of the pest is relatively simple. There are three systems currently used :

• Brushed, sprayed and/or injected liquid insecticide
• Enveloping the object in a gas, either as a direct poison or as a means of excluding oxygen.
• More recently a heated humidity controlled environment has been used with excellent results.
• Occasionally furniture has been infested by the deathwatch beetle (Xestobium rufovillosum). The insect needs damp wood which supports a fungal growth, which in turn makes the wood digestible, before it can set up home.

The prolonged causes of dampness in buildings permits the onset of fungal growth. If these conditions are permitted to extend to the furniture within them, these too will become susceptible to fungal attack. Fungus, in this situation will cause staining and also weaken the adhesives. A fine whitish "growth" is sometimes found on or in furniture where damp conditions may not be suspected. This can be a mild type of fungus but is more likely to be some form of crystallisation. In both cases the deposit may be brushed off and wiped away with a dry cloth.

Human Intervention

Events over a period of time impart a unique quality to each piece of furniture, and it is primarily people's intervention that has and is governing each item's acceptability. It is the Restorer's privilege to make acceptable those items that have been subject to unfortunate circumstances.

The aim of the custodian, for that is what we are when we have antique furniture, is to maintain its good health. Furniture that has been with the family for a decade or more and not caused concern is unlikely to present problems providing its past treatment is unchanged. However, a newly acquired item may be subjected to a considerable change to its environment, therefore we should not be surprised if movement occurs within the piece. Unless there are already significant tensions between the structural units, damage resulting from the move may not happen for several months. Conversely the new environment may be a kinder place.

Moving Furniture

Much damage occurs when objects are moved. This can be avoided if the item's construction is wholly understood. Failing that there are a few simple rules that will help avoid embarrassing moments:

Furniture should be lifted by its strongest units or rails: chairs, including arm chairs, by their seat rails, tables, by the rails/frieze below the top or by the legs., cabinets and chests by their lowest rails or at "foot level" and not by the top.

In principle NEVER DRAG furniture, not even for an inch/centimetre. In practice, if there is no alternative, then the dragging force must be as close to the floor as possible.

Preventing Surface Damage

The main causes of surface damage are:

Liquids of all sorts, excessive heat and scratches and bruises.

Unless there is a mat providing softening under a heavy object or vase never slide it; it will scratch. If the mat is absorbent it may trap spilt water under a vase. A damp seal - polyurethane perhaps - needs to be put between the mat and the wooden surface.

Spilt water and water based liquids should be wiped off to prevent them spreading and the surface rubbed dry. Spirits and other solvents must be dabbed off to prevent them spreading and should not be rubbed dry, lest they have softened the surface finish which could then be deformed/marked. A common and very defacing bruise is caused by drawing with a pencil or writing with a ballpoint pen on paper with no softening between it and the wooden surface.

Removing any bruises from polished wood, without removing the surface is seldom possible and any process carries considerable risk of damaging the patina and changing the surface colour. Not only will the direct sun's rays overheat furniture, they will cause severe bleaching of the wood and make the polish cloudy. Drawing the curtains until the sun has passed is the simple remedy. It may be argued that the opaque polish, caused by the water soaking into the top, or by too much local heat, and the scratches and bruises are part of the history of the object. Realistically these are elements of history that are generally best forgotten, even if the experience of their occurrence is a valuable lesson. In each of these accidents it is best not to compound the problem with trial and error remedies, but seek help from a convenient BAFRA Member.

These then are the prime causes of deterioration of furniture and with them, a few suggestions which may help to retard the inevitable aging process.

Note: For greater detail read : "Manual of Curatorship: A Guide to Museum Practice". 2nd Edition ISBN 0 7506 0351 8. (c) John W. L. Kitchin

CARE OF ANTIQUE FURNITURE - ENVIRONMENTAL CONTROL

By Valerie Taplin, Air Improvement Centre

The following text is reprinted from the Air Improvement Centre antique care leaflet. Copies are available, free of charge.

Much of the damage to furniture has been caused by central heating dryness, and it makes sense to suggest that the client installs a humidifier, preferably before the restored piece is returned home. Occasionally, there is the opposite problem of excessive dampness, especially in unheated premises, or storage areas.

HOW TO PROTECT IT FROM THE RAVAGES OF CENTRAL HEATING

SITING

Furniture should never be placed directly in front of a radiator. It should ideally be at least two feet from any heat source. If a piece of furniture really has to be placed near a radiator, a possible compromise would be to devise an insulating protective ‘barrier’. This could take the form of a decorative fire screen with an insulated/reflective backing.

A humidifier can be sited anywhere in the room near an electric socket, but not under a piece of furniture or in front of a fireplace or open chimney. A good position would be behind a sofa, and in front of a radiator, so it is hidden from view but the rising heat helps circulate moisture in the convection currents. Most house plants relish additional humidity, and can be used to hide the humidifier. Some interior designers have come up with ingenious ways of concealing a very functional humidifier within an aesthetically-pleasing cabinet.

ENVIRONMENTAL CONTROL

Antique furniture needs protection from low levels of relative humidity caused by central heating. Without humidification the relative humidity may well fall to dangerously low levels of 25-30% rH which is close to that in the Sahara Desert.

USE A HUMIDIFIER IF YOU HAVE CENTRAL HEATING

Prevention is always better than cure. It is possible to safeguard antique furniture from dry air damage by investing in a good humidifier which will help maintain a constant level of relative humidity in the air during winter heating. Simply placing a bowl of water or a pot plant near a piece of antique furniture is of little value in protecting it from the effects of central heating. For a normal comfortable indoor temperature of 70ºF, aim to maintain 50-55% relative humidity.

Electric Humidifiers

The choice of humidifier depends on room size and purpose. It is important to get specialist advice on the most suitable model.

Humidifiers incorporate a safety cut-out to switch off automatically should you forget to refill. They are also silent, completely hygienic, and simple to use. They are suitable for use with hard water, and need only to be descaled periodically as for a kettle.

Different Features and Types of Humidifiers

Electric humidifiers operate by various different principles, each with different features:-

Steam evaporation - Produces gentle, warm, visible steam. Silent (no moving parts). Hygienic (sterile in operation), good moisture distribution. Easy to clean. No filters to change. Suitable for hard or soft water.

Fan-assisted evaporation - Produces cool, invisible moisture. Motor noise. Regular cleaning essential to avoid stagnation. Need filters changed regularly.

Ultrasonic/atomisation - Produces jet of visible cold mist. Humming noise. White chalk dust deposits on surrounding surfaces. Localised effect. Needs water softening cartridges changed regularly. Use distilled or very soft water.

N.B. For Health/Medical Use:

Steam evaporation humidifiers (such as Turmix) are the only ones which are completely silent and suitable for use in nurseries, bedrooms and sitting rooms (no moving parts, no ultrasonic humming). The Turmix also holds enough water to last right through the night (safety cut-out).

They are also suitable for use in hard water areas. Any minerals in the water are left behind in the water tank, which needs to be descaled periodically (as with a kettle). Only pure water vapour is produced into the room (unlike with ultrasonic and atomisation humidifiers which spray a fine film of white chalk dust onto surrounding surfaces).

Similarly, because the steam has been heated, it is completely hygienic - the gentle warm steam from the Turmix 200 is frequently used for inhalation to ease congestion (with eucalyptus or tea tree) or aromatherapy (with lavender or camomile etc. which are calming and soothing).

Non-Electric Humidifiers

If you prefer non-electric humidifiers, use a large capacity hang-on radiator humidifier. These should be used on all radiators in the rooms concerned.

Such humidifiers can be hidden within radiator housings. The front of the housing needs to be hinged to allow easy access for daily filling.

You cannot over-humidify with these non-electric humidifiers. To get the best output, use the largest size that your radiator can accommodate and remember to fill daily. Essential oils can be added if desired.

Hygrometers

Be sure to use a hygrometer to check that the relative humidity stays in the region of 50-55%.

Glossary of WOOD FINISHING Terms