Ivory is extremely sensitive to humidity and temperature fluctuations. The most important factor is keeping conditions as constant as possible to prevent shrinking and expanding. Extreme conditions or rapid fluctuations should be avoided (something to consider if shipping your canes from one climate to another). It is suggested that the humidity level be maintained at a level between 45-55%, with a temperature of between 65-72 degrees. Too much moisture, i.e. over 70%, can cause mold and mildew damage, including black spots and etching of the surfaces, warping and swelling. Avoid direct heat or outside walls, cold windows or any source of moisture condensation (basements or attics).
Avoid placing ivory pieces in direct sunlight. Direct sunlight raises the temperature and lowers the humidity, contributing to cracks and color change, specifically bleaching. Low light levels offers the best protection.
Antique ivory should be handled with care. White gloves are suggested; if not available, wash your hands carefully to remove hand oils and dirt, as ivory darkens as a result of contact with skin oils. Some darkening, or patina, is the result of the natural aging process. Ivory is porous, and susceptible to staining, so keep separate from corroding materials and other colored materials.
Methods of ivory hydration
Ivory tends to dry out with age. The older the ivory, the more brittle. A very light vegetable oil can be used to hydrate directly (avoid on scrimshaw as inks may run). Also suggested, every 6 months or so, wrap ivory pieces in soft cloth saturated with mineral oil or glycerin. Allow to sit overnight and wipe off the excess in the morning.
Never attempt to remove the surface coat pigment or patina, as it affords protection for the piece, and is an indication of age. Many liquids, including water and cleaning solutions, are destructive to ivory, and should be avoided. Applying water may cause swelling and cracking. Extremely dirty pieces should be referred to a professional conservator, as well as pieces that are dyed, pigmented or inlayed. When in doubt, consult with an expert.
Dry cleaning methods may be attempted: Using a clean, soft paintbrush or toothbrush, carefully brush dirt off the object.
Ivory that is in good condition should be cleaned and wiped gently with a soft, clean cloth. If dirt remains, but no cracks, using a solution of 50% ethyl alcohol and 50% distilled water, dip a Q-tip into the solution and blot on a piece of paper towel. Use this to clean a small, inconspicuous area, and dry immediately. If this goes well, clean the entire piece in this manner, working on one small piece at a time, and drying immediately.1
Remember: When in doubt, consult with a professional.
1. The Cane Collector’s Chronicle, Volume 4, Number 1, January, 1993.