Urushi is a very durable material. Historical examples of lacquerware hundreds of years old can be found in exquisite condition with barely any deterioration in its finish even after decades of use. However, lacquerware is not impervious to damage. When misused, lacquerware is still prone to the chips and scratches that any other object can sustain. In addition, urushi has a few particularities when it comes to its care:

Do not expose urushi to sources of strong ultraviolet light. This includes but is not limited to direct sunlight, halogen lamps, black lights, and disinfecting cabinets. Exposure to ultraviolet light will cause discoloration as well as cracking, crazing and deterioration of surface luster. To maintain prevent minor cosmetic changes in color, urushi should be stored in a dark place when not in use.

Do not clean urushi with abrasives or harsh chemicals. Although urushi can withstand many every day chemicals such as alcohol, acids and bases, it will not withstand some harsher chemicals. Wash lacquerware with a simple detergent and water with a soft, non abrasive sponge or cloth. Dishwashers are also not recommended because of the high heat and rapid temperature changes involved. Abrasive cleaners will mar the finish of lacquerware.

Do not place urushi in the microwave, or expose to open flames, extremely high heat or rapid temperature changes. Although urushi itself can withstand very high temperatures, most lacquerware has wood, resin or hard rubber as a core. Microwaves can also cause excessive drying and cause a piece to craze or crack or the metal powder or foil used in the lacquer will react adversely to the microwave radiation.

Do not store urushi in a dessicating environment. Excessively drying environments such as refrigerators as well as some naturally dry locations around the world may cause wood substrates to deform or crack. To prevent this, refrain from storing lacquerware in the refrigerator for extended periods and if you live in a dry environment, store lacquerware with a glass of water. Lacquerware with acrylic or ebonite substrates as well as lacquerware done in the kanshitsu technique are less susceptible to this type of damage.

Do not stack lacquerware with harder materials such as metal or ceramics. When stacking multiple pieces of lacquerware, place a square of soft cloth or tissue between each piece. Although the surface is resistant to wear from every day use, it is not impervious to scratches.

Aside from these main precautions, lacquerware can be maintained with minimal effort in care. However for more exquisite pieces, additional precautions should be taken to maintain the beauty of the piece:

Do not leave urushi under water or containing water for an extended period of time. This is not a problem regarding the insides of a fountain pen.

Do not store oils, acids, bases, or alcohol in lacquerware for an extended period of time. Although it is safe to use lacquerware with these substances, an extended period of time in contact with them may cause problems. Avoid placing hot oil or fried foods on lacquer as it may discolor it.

Keep raden and rankaku away from acids and ink. Both raden (mother-of-pearl) and rankaku (eggshell) can be damaged by acids. 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 gently with a soft, damp gauze. This especially for lacquer pieces such that have fine detailing. Be sure not to rub too vigorously.

Dry lacquerware throughly before storage. Mineral deposits in waterspots may cause scratches if rubbed.

Store lacquerware in a cool dark place. Exposing lacquerware to long periods of visible light may cause discoloration and some reduction in gloss.

Store lacquerware with a cup of water. If to be stored for an extended period of time, especially in areas with particularly low relative humidity, place a cup of water along with the lacquerware in the cabinet. This will prevent cracking from excessive drying

* Source from Hakumin Urushi Kobo