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The purpose of this article is to provide owners of solid wood furniture with sound practical advice and the key trade knowledge required to maintain their furniture. The first part focuses on the essential theoretical aspects that support the practical recommendations found in the later sections.

Timber consists of many interlinking cells. While the tree is alive these cells retain moisture, principally nutrients absorbed through the roots and food sugars produced by the process of photosynthesis acting upon the absorbed nutrients in the leaves. When the tree is harvested and converted, usually by milling, into material suitable for furniture and joinery manufacture this moisture has to be reduced to levels that ensure the timber will be free from fungal attack such as dry rot and is also dimensionally stable, a process traditionally known as “seasoning”.

The moisture is held in the timber in two main forms, “free water” which fills the cell cavities and “bound water” which is held within the cell walls. During the drying process the free water is given up first. Not until all the free water has been removed is it possible to remove the bound water. In most timbers this is a moisture content of around 28%; this point is generally known as “fibre saturation point”. As the moisture content is further reduced we begin to observe the majority of the shrinkage, which is associated with the drying of timber, taking place. British Standards recommends a moisture content of 12% for internal joinery; in practice many modern homes have such low ambient moisture that timber moisture levels need to be reduced substantially lower than 12% if further shrinkage of the material used in the finished furniture is to be avoided.

In the past the process of seasoning involved stacking the converted timber “in the stick” in well ventilated but reasonably sheltered accommodation. Over a period of some years, depending on the thickness of the planks, this resulted in the timber achieving a moisture content proportionally equal to the prevailing atmospheric moisture levels. Timber thus dried will have reached the ambient moisture level and is often known as “air dried”. In practice this seldom results in a moisture content of less than 16% with 18-20% being the norm in the UK. 20% is also the level at which timber becomes free from dry rot attack.

As stated earlier, to ensure dimensional stability, timber needs to attain a moisture content equivalent to that of its surrounding environment. Currently this is achieved by kiln drying. In an ideal world the timber used in any particular piece of furniture would be dried to match the moisture content of its proposed location, but this is seldom possible. All cabinet-makers will however make allowance in the construction detail of their furniture to accommodate some further shrinkage and possibly expansion. But if substantial further shrinkage does occur then deterioration of the finished piece of furniture is to be expected.
However it is not all doom and gloom, and there is much that owners can do to ensure that their furniture will last for many generations.

First and foremost consider the environment the furniture is in. Perhaps the best question to ask is, do I feel comfortable in this space? Because it’s generally true to say that if we are uncomfortable then so is our furniture. Can we feel the dryness of the atmosphere on the back of our throats? If so then the room is certainly too dry. Is the room clammy and damp? These extreme conditions are best avoided and can certainly be remedied by simple measures. Having a few house-plants in rooms that are very dry and even keeping the odd saucer of water near to central heating radiators (obviously avoiding contact between water and electrical equipment) will help to keep humidity levels within a comfortable range for both humans and furniture. In rooms that have high humidity levels the regulated use of dehumidifiers may be appropriate. Obviously with very damp rooms more elaborate constructional measures may need to be undertaken, such as the installation of a suitable damp proof course or the replacement of poorly fitting and degraded joinery.

Try to ensure that solid wood furniture is shaded from direct sunlight. This will help avoid damage to both the surface finish and also to the underlying timber, where surface checking can be the result of continuous exposure to the sun’s rays. It is also worth remembering that exposing veneered antique furniture to the sunlight may result in softening of the adhesive, resulting in the lifting of the veneer, frequently characterised by unsightly bubbles on exposed surfaces.

Having dealt with environmental extremes, we should next consider how we use our furniture. Flat surfaces should be protected from the items placed on them, so tablemats and coasters should always be used and spills should be mopped up immediately. Try always to use the item for the purpose it was intended for. Sitting on tables has often resulted in substantial damage, and overloading drawers is a common cause of damage to both the drawer and the carcass in which it is housed. If drawers stick, try to avoid forcing them; a little talcum powder sprinkled on wooden runners is frequently all that is required to make them work. And let’s not forget the consummate form of furniture abuse, that of leaning back on chairs. This is perhaps the single most effective destructive activity, a seemingly effortless action frequently resulting in substantial damage.

Having ensured both our own comfort and that of our furniture we come to the subject of cleaning and polishing. General cleaning is best effected by the use of a soft cloth, although today there are some very effective dusters, which collect dust due to a small static change. The activity of polishing appears to be divided between two camps, those who see it simply as a chore and those who regard it as a therapeutic pursuit. Whatever your approach here are some simple guide- lines. Always ensure that the item to be polished is free from dust, as simply applying polish to a dusty surface will result in an unsightly build up of detritus in the corners; if the dust particles are of sufficient size then scratching of the surface may also occur. Use only natural products. A simple mutton cloth and a polish consisting principally of beeswax is generally all that is required. Apply a little of the beeswax to the soft cloth, then work this over the surface with a circular motion. This should then be buffed up again using a soft clean cloth and working along the grain. This care is all that is needed for most pieces of furniture. For furniture that has been finished with an oil a gentle dusting from time to time is all that is required. Should small scratches occur, applying a little of the original oil is often all that is needed to effect a repair. Small scratches in surface finishes such as french polish and nitrocellulose lacquer can be dulled by rubbing the kernel of a pecan nut or even a brazil nut into the affected area. Since the pecan generally contains a greater amount of oil it tends to be the most effective. A black felt tipped pen can also be helpful in certain circumstances.

Over time the original lustre may become dulled and jaded, and in such circumstances a reviver may be required. Many proprietary brands are available but the following simple recipe can be most helpful in removing small traces of dirt and grease. Mix together one part linseed oil and one part vinegar and work over the surface with a soft cloth. Then clean off the residue. After cleaning with a reviver, wax as normal.

As with the reviver many proprietary brands of wax furniture polish are available but the following is simple and effective: dissolve shredded beeswax in pure American turpentine until a consistency of a thin paste is achieved. This process may be hastened by heating the container in hot water. (Avoid contact with a direct heat source, since turpentine and its substitute are both highly flammable.) Turps substitute may be used instead of pure American turpentine but the distinctive aroma will be lost; if desired a little perfume may also be added to the recipe.

One last precaution. If you are unsure of the finish you have on your furniture or of the product you intend to use it is always wise to carry out a test on a small hidden area of the piece to be treated. Many an unhappy consequence has been avoided by this simple expedient.

For those wishing to gain a fuller knowledge of the subject then Staining and Polishing by Charles H Hayward (Bell and Hyman 1983) is an excellent starting point. (This book is now out of print but copies are often available.)