Furniture PolishesThere are several factors to weigh when deciding to use polishes and waxes on furniture and other wooden objects. One critical factor is that the ingredients in commercial polishes and cleaning products are rarely disclosed. Moreover, these ingredients can be, and frequently are, changed without warning or notification. These ingredients may be harmless or harmful to the furniture (and to you) and you have no way of knowing in advance.
Polishing products are available in three forms: aerosol (spray); liquid; and semisolid. Here is a quick look at their benefits and drawbacks:
Oil polishes are even more troublesome. Much like emulsion polishes, oil polishes can be a complex blend of ingredients including oils, waxes, perfumes, colorants, "cleaners," and organic solvents. They can render extremely pleasing surfaces and are used frequently as final finishes by themselves. However, oils used as polishes or cleaners can be very damaging.
- Nondrying oils (paraffin, mineral, and "lemon oil," which is usually mineral oil with colorants and perfumes added) tend to be more benign than drying oils, but even so some oil remains as a liquid on (or in) the object. Dust and other airborne contaminants readily stick to wet surfaces, especially oils. But nondrying oils don't undergo chemical reactions or directly damage the furniture.
- Drying oils, on the other hand, such as linseed, tung, or walnut oil, are a different matter altogether. These materials solidify, or "dry" through a chemical reaction with the air called oxidation. Over time this reaction makes them increasingly difficult to remove. Their permanence is fine if the oil is employed as the finish, but not good if it is used as a maintenance polish. By itself, having a polish that is difficult to remove would be an irritating but not an insurmountable problem. Unfortunately, as drying oils age they tend to yellow and in the presence of acids they are chromogenic (become Colored), turning a dark, muddy brown or opaque black.
- Traditionally, cleaning and polishing concoctions comprised of linseed oil, turpentine, beeswax, and vinegar (acetic acid) were widely used even in the museum field until recently. They turned out to be a disaster waiting to happen. The results of their use are readily apparent to even the casual observer: a thick incrustation of chocolate-colored goo that is neither hard enough to be durable nor soft enough to wipe off easily. The furniture is left with an unsightly coating that is very difficult to remove without damaging the underlying surface.
Fortunately, as the most durable and stable polishing material, paste wax needs to be applied much less often than aerosols or liquids. Ideally, wax polishing should be conducted no more than twice a year for areas of extremely heavy wear (desktops, chair arms, etc.) and once every three or four years for table and chair legs, cabinets, and similar areas.
If a surface can no longer be buffed to the sheen appropriate for a waxed surface, it is likely that the wax has worn off. In that case, apply another light coat of wax to the affected area in accordance with the product instructions. Wax that is applied too frequently or improperly can build-up and cause an unsightly surface. When the wax is used correctly, however, the solvent content of the new wax will "clean off" any previous wax remaining on the surface and will simply integrate the old into the new.