The guidelines for furniture maintenance are pretty simple. If the furniture is used wisely and handled carefully, it will need very little in the way of routine maintenance. But in cleaning and polishing furniture surfaces and hardware, and in re-upholstering, some well-intentioned caretakers introduce damage. In fact, a lot of what furniture conservators do is respond to destructive maintenance practices.
For the most part, maintaining furniture simply means keeping it clean, carefully. Wood furniture usually needs to be cleaned only when there is a buildup of wax or dirt. Only unfinished wood, painted wood, or wood with a sturdy finish should be cleaned. The finish on giltwood is often applied with a water-soluble size, or adhesive; it should be carefully dusted, not cleaned, or cleaned only by a professional.
Before cleaning wood or coatings, the first and most important step is to evaluate the surface and make sure that the surface or coating is stable and not apt to be damaged by the contact required in cleaning and polishing. If the surface is unstable, the polishing could knock off loose portions. Damaged surfaces should be referred to a conservator.
After the soundness of the surface has been established, the next step is to find out what the dirt is and what the surface is. If you can't determine these exactly, find out what removes the dirt without affecting the surface underneath it. Often, dust can be removed with the careful wipe of a damp cloth. Oily dirt or waxy residue can be removed with a mild detergent and water solution or with mineral spirits. However, it is vital to make sure that the cleaning solution does not affect the underlying surface. Even when you determine a cleaning method that works successfully, proceed cautiously.
Loose dust on the surface can be removed with a soft, lint-free cloth, gently rubbed over the surface. Dust is an abrasive and can scratch the surface, so be careful. Uneven areas can be dusted with a clean, natural bristle paint or artist's brush. Again, do not try to dust a surface that is severely deteriorated. Cloth fibers can catch and tear away pieces of the finish, veneer or loose parts. Even rough edges can splinter. Carving, fretwork, and other delicate work can be dusted with a soft bristle brush, with a vacuum cleaner host held close enough to take in the dust one it is dislodged by the brush. Do not use feather dusters, as they can scratch and pull off loose fragments of veneer.
Surfaces in good condition but with a heavy accumulation of dust can be cleaned very carefully with a vacuum cleaner. Use the lowest suction available and the round brush attachment. Don't let the metal or hard plastic parts of the vacuum bump into the surfaces; they can scratch the finish or wood. Much damage, in fact, occurs as the feet and bases of pieces are hit with the vacuum cleaner.
Dirt that cannot be simply vacuumed off may be removed with cleaners mixed in a dilute solution, but only if the finish is in good solid condition. First, determine which solvent removes the dirt without removing the finish. Those to be tested include mineral spirits (white spirit), paint thinner, and naphtha. Second, test a small spot in an obscure area with the solution on a cotton swab. All areas that appear to be a different coating or material must be tested separately. Only if the solution does not damage the test area should it be used to clean the rest of the piece.
For finished wood, dampen a cotton cloth with the solvent or cleaning solution, and gently rub over a small area at a time. Avoid using too much liquid, as they can cause damage. Then, wipe the cleaned surface with a clean dampened cloth to remove any cleanser residues, followed by a dry soft cloth.
Following simple cleaning, further protection and aesthetic enhancement can be obtained through the application of a stable, hard furniture polish, such as a hard paste wax. The hard wax surface can be dusted more easily because it will be more smooth, and the dust will not be imbedded in it as it would in an unwaxed surface. Waxing need only occur infrequently because the wax itself is not readily removed and it does not degrade chemically. Waxing too often can result in a built-up, clouded surface.
This simple approach avoids the problems created by popular methods of "furniture polishing" - such as sprays and oily polishes - that may result in cumulative damage to furniture. Many polishes and residues continue to be a vexing problem for furniture conservators, as they can build up over time and with numerous applications, trapping and adhering airborne dirt onto the surface.
Dusting upholstery can be accomplished by a vacuum cleaner. Place a soft screen on the surface to prevent any snagging or abrasion from the vacuum tip, and using a brush attachment, carefully vacuum the surface.
Stains and other damage to upholstery should be referred to an upholstery or textile conservator for further treatment.
One never-ending concern of furniture caretakers is for the hardware, including handles, brackets, hinges and escutcheons attached, usually with nails, to the outer surface of a piece. The metal in hardware might be brass, silver, gold-plated bronze, depending upon the style, date and country of origin. Contemporary hardware attachments sometimes have a clear lacquer finish that gives them a shiny appearance. Antique hardware is also sometimes coated by restorers and conservators to eliminate the need for constant polishing. There is currently a lot of debate in the conservation field as to whether metal hardware should be lacquered or polished. Neither is an option is there is evidence of an original varnish or if abrasive polishing would remove some other original surface treatment.
Furniture hardware may become dirty and tarnished with use and exposure to the atmosphere. In such cases, polishing it can be justified. However, even this step is sometimes a poorly informed one. One common example of the damage is created by polishing hardware supposed to be brass, when it is really gilded bronze that is simply dirty. Polishing removes the gold, damaging the surface of a beautiful sculptural element.
If you choose to polish, remove the hardware from the piece, noting the exact location of each screw and nut. Polishing the hardware while on the piece damages the surrounding finish and also allows polishes to run beneath the hardware that can further damage both the metal hardware and the finish.
Clean hardware carefully with a 50/50 mix of acetone and alcohol to remove any dirt and oil residue, scrubbing the piece with a soft bristle brush. After drying, the surface can be polished with a fine, lint-free cloth of felt block charged with a very fine abrasive, such as calcium carbonate or jeweler's micro polish, in an alcohol or mineral spirits slurry. Commercial polishes can contribute to the deterioration of the hardware, as they frequently contain harsh cleaners that corrode the metal.
If the hardware cannot be removed safely from the furniture it can be polished and coated on the object provided the following precautions are scrupulously followed. First, the surface of the wood and varnish must be completely protected. Acetate sheets, such as those found in office supply stores, can be notched and slid under the hardware from both sides to form an overlapping barrier. Without this precaution, attempts to polish the hardware will likely end in disaster.
Since this hardware cannot be doused with the acetone and alcohol mixture, cleaning must be done by dipping swabs in the solution, then rubbing the metal surface with the swab. Polishing must also be done more carefully, perhaps on a smaller scale.
After polishing, remove all residues. The surface of the hardware that has been removed from the furniture can be easily coated with a transparent resin before the hardware is replaced on the piece. Particular care must be used in applying any coating when the hardware cannot be removed, to make sure that no protective varnish for the hardware gets on the furniture piece itself.