Caring for Urushi Lacquerware
Urushi, a natural lacquer used in Japanese lacquerware, is naturally cured through a process of oxidation and polymerization into a material with remarkable properties for a natural substance. Once hardened, urushi forms a tough and scratch resistant surface impervious to water, alcohol, minor heat, acids and bases. But to maintain it’s beauty, there are a few things you should be aware of to take good care of your precious urushi lacquerware pieces.
Urushi lacquer is very sensitive to light especially ultraviolet light (below 400nm). To prevent damage, avoid exposing lacquerware to strong or direct sunlight, ultraviolet light and long exposure to light.
Overexposure to light is urushi’s greatest weakness and can cause noticeable discoloration and loss of lustre and gloss of the lacquer surface. Severe overexposure (especially to ultraviolet light) can cause additional damage including cracking or crazing of the surface, and as a result, exfoliation of the lacquer layers. In an average setting, this type of irreversible damage will usually not happen, but prevention is best practiced.
Prevention is not a difficult task. Simply avoid displaying and using lacquerware in and around strong sources of light will prevent any severe damage. Sunlight remains the strongest source of ultraviolet light typically encountered. Avoid using lacquerware outdoors during daylight hours and do not place or display lacquerware in front of a window or in other places where strong or direct sunlight may enter. (This means if you have nice lacquerware go equipment, you probably wouldn’t want to play it outside with your friends on a sunny day.) Halogen lamps may still be encountered frequently for display lighting in stores and sometimes in the home. Although halogen lamps typically come with UV filters which effectively block a large portion of the emitted ultraviolet light, due its strong intensity and high temperatures, please avoid displaying lacquerware under halogen lamps. And do take care not to use a halogen lamp with its UV filter removed. Likewise, lacquerware should also never be sterilized in a UV based germicidal or sterilization chamber as these use strong doses of ultraviolet light in the most damaging spectrum (UV-C, 280-100nm) to kill pathogens. Other sources of ultraviolet light include various less common light sources such as high intensity discharge lamps, specialty gas discharge lamps, and certain high intensity LED lamps. Most of these particular sources of ultraviolet light would not be encountered in a normal setting, but should be avoided should the case arise.
Ultraviolet light, however, is not the only portion of the spectrum that may damage urushi. Although the level of damage is drastically reduced, visible light can also noticeably deteriorate a lacquer surface. Frequent, extended exposure to the visible spectrum can cause a noticeable change in color and a reduction in luster and gloss in as little as 6 years for transparent or lighter colored lacquer surfaces and 21 years for black lacquer surfaces. In practice, this type of damage is difficult to achieve in a typical household setting, but it becomes understandable when it is suggested that urushi should not be put on constant display and be illuminated only when they are actually being viewed. Maki-e lacquerware with a heavy layer of exposed metal powder covering the entire surface will experience very little or no damage from this type of exposure.
Heat is also a factor in damage caused by lighting. Excessive heat over long periods of time also contribute to the surface deterioration in lacquerware. If lighting must be used in close proximity, only low temperature lamps such as fluorescent lamps should be used and they should be arranged to reduce the amount of heat as much as possible.
Beware of the microwave oven, open flames, extremely high heat and rapid temperature changes. Although urushi itself can withstand very high temperatures, most lacquerware have a core made of wood, resin or hard rubber. Microwave ovens can also cause excessive drying and cause a piece to craze or crack; also the metal powder or foil used in the lacquer will react adversely to the microwave radiation.
Avoid cleaning urushi with abrasives or harsh chemicals. Although many every day chemicals such as alcohol, acids and bases will not damage urushi, it will not withstand some harsher chemicals. Wash lacquerware with simple detergent and water using a soft, non-abrasive sponge or cloth. Dishwashers are also not recommended because of the high heat and rapid temperature changes involved. Beware that abrasive cleaners will mar the finish of lacquerware.
Beware of storing urushi in excessively drying environments as the wood substrates may deform or crack. To prevent this, refrain from storing lacquerware in the refrigerator for extended periods. If you live in a dry environment, do store lacquerware with a glass of water.
Stacking can cause unnecessary scatches to urushi. Don’t stack lacquerware with harder materials such as metal or ceramics. If you do stack multiple pieces of lacquerware, place a piece of soft cloth or tissue between each piece. Although the surface is resistant to everyday use wear, it can scratch.
Aside from the above main precautions, lacquerware can be easily maintained without much effort in care. However for more exquisite and expensive pieces, additional precautions should be taken to maintain the beauty of the piece:
– Don’t leave urushi under water or store with water inside for an extended period of time.
– Don’t store oils, acids, bases, or alcohol in lacquerware for an extended period of time. Although it is safe to use lacquerware with such, an extended period of time in contact with them may cause problems. Avoid placing hot oil or fried foods on lacquer to prevent possible discoloration.
– Keep raden (mother-of-pearl) and rankaku (eggshell) away from acids and ink to avoid damage. Pieces with exposed raden or rankaku inlays should be kept away from sources of acid such as vinegar or citrus juice and some inks. Such pieces should also be wiped clean before storage to wipe away the traces of acid from fingerprints and sweat. Ink may also stain these materials.
– Wash lacquer pieces gently with a soft, damp gauze, especially for those with fine detailing. Restrain from rubbing too vigorously.
– Dry lacquerware throughly before storage to avoid mineral deposits in waterspots which may cause scratches if rubbed.
– Store lacquerware in a cool dark place. Remember that exposing lacquerware visible light over a long period may cause discoloration and some reduction in gloss.
– Store lacquerware with a cup of water to prevent cracking from excessive drying. If to be stored for an extended period of time, especially if you live in areas with particularly low relative humidity, please place a cup of water along with the lacquerware in the storage cabinet.