Easy tips for cleaning ivory and bone

Ivory and bone need to be treated with care. Whether you're cleaning a figurine, game pieces or a beaded necklace, you must also assess the condition of the item, because that will determine your approach.

• Whether it's ivory or bone depends on the animal your ivory piece came from. If it came from the tusk of an elephant or mammoth you have true ivory.
• Today, however, the tusks of other mammals, such as those of walruses and certain whales, and some synthetics are considered ivory as well.
• Ivory is chemically similar to bone and antler, but there are differences. Ivory has no blood vessels, whereas bone does. Bone is fragile and porous, whereas ivory is dense. Ivory and bone are similar in this respect: They're sensitive to heat, light and moisture.

• Take it to a conservator to be cleaned.
• Because ivory readily absorbs oils and stains, wear white cotton gloves while working with ivory, or, at the very least, wash your hands with soap and water to remove oils and dirt.

• Clean off the surface dirt with a barely damp cotton cloth or cotton swabs.
• To dampen, use a solution of mild dishwashing liquid and water or use just water. If you use too much moisture, surface fractures may appear on the ivory.
• Now wipe the surface of your item with a dry cloth and apply a second cloth or cotton swab dampened with mineral turpentine to remove any soap residue.
• Wipe with a dry cloth.
• Never rub the surface of ivory and bone. You don't want to remove the original surface coats, pigments or patinas.

• Use a cloth or cotton swab that has been barely dampened with mineral turpentine.
• If your ivory or bone has scrimshaw (engravings or decorations) on it, test an inconspicuous part of the scrimshaw to see whether it will withstand the cleaning technique.
• If it doesn't react well to the test, don't clean the scrimshaw yourself, take it to a conservator.

• You will have to take it to a conservator. These stains are usually due to oxidation that comes with age or may be caused by the oils on your hands.
• Sometimes, placing the ivory or bone in sunlight bleaches it and helps it regain its warm white colour.
• Keeping ivory or bone in the dark accelerates the yellowing associated with aging. But do not expose ivory or bone to long periods of intense sunlight or heat, because that will dry it out and cause it to crack.

• Store items in a carefully controlled environment, ideally 45 per cent to 55 per cent relative humidity and about 21°C (69°F), in low light.
• Conditions should be kept constant, as the most severe damage to ivory and bone is caused by fluctuations in humidity and temperature. Low humidity will dry ivory out, causing shrinkage and cracking. High humidity and changes in temperature can cause your ivory to expand and contract.

All of the following factors may damage your ivory or bone:

• display areas exposed to sunlight or a spotlight;
• a closed display case with light bulbs inside, heating the interior;
• nearby ventilation or heating ducts, the tops of appliances or other sources of heat or cold;
• sulfur in rubber-based paint, storage materials and adhesives, because sulfur in rubber can discolour ivory.