Basic care – Ivory, horn, bone and antler objects

Ivory

Ivory is a specialized form of tooth. The most common source is elephant tusk although other mammalian tusks (e.g. walrus, sperm whale tooth and narwhal) have been used. A synthetic "ivory" was produced from cellulose nitrate in the late 1800s and early 1900s. Called "French" or "India" ivory, it resembles the real thing, but its structure breaks down over time.

Bone

Bone looks similar to ivory, but it is lighter in weight and usually not as white. A polished bone surface usually has small pits and what appears to be a lightly scratched surface; these are the exposed "tunnels" that pass through the bone.

Antler

Antler is a specialized form of bone that often has a rough textured surface.

Horn

Horn is made up of the same material found in fingernails or hooves.

Causes of damage

Contact with the natural oils of skin or exposure to coloured materials can result in staining or darkening of ivory and bone. Over time, exposure to the environment can also produce some darkening in ivory which can be considered a patina. Other causes of damage include:

• exposure to light – it can bleach ivory;
• insects can damage horn;
• extreme or rapid fluctuations in temperature and humidity cause small changes in dimensions, which can lead to cracking; and
• liquids such as cleaning solution or even water can also cause damage.

Handling

Ensure that your hands are clean and dry before handling ivory, bone, horn and antler.

Safeguard items from extreme or rapid changes in temperature or humidity; a display case will provide some protection against environmental fluctuations, dirt and dust. Do not display ivory, bone, horn and antler in direct sunlight, under bright lights, near heat or air-conditioning units or near windows and exterior walls.

When storing items, wrap them in unbuffered, acid-free tissue paper or unbleached muslin and then place them in a sealed polyethylene bag (e.g. Ziploc freezer bag).

Do not use rubber-based materials (which can cause yellowing) to cushion items made of ivory.

Cleaning and repairs

A light dusting with a soft brush is often all that is needed to clean ivory, bone, horn and antler objects. Ivory and horn that are in good condition (i.e. with a smooth, glossy surface) and have no applied decoration can be cleaned with a little water. Use a cotton swab (e.g. Q-tip), barely dampened, and dry the object immediately with another cotton swab or soft tissue. Do not attempt to clean porous bone or antler this way without first consulting a conservator. Do not use water on any object that is cracked or otherwise damaged. Never soak objects.

The cleaning and repair of ivory, bone, horn and antler is a delicate procedure. If an object is very dirty or damaged, consult a professional conservator.