While the following criteria may not be necessary for most shofarot, they should be considered if you are responsible for the care of an antique or historical shofar. Note, especially, the warning against moth larvae (emphasis added). I had heard about this threat, but this is the first reference I have found from an authoritative source. If you have more information about this, please contact me.
Excerpts from:
Canadian Conservation Institute Notes 6/1
Care of Ivory, Bone, Horn, and Antler
Introduction
Many museums have objects that are made from ivory, bone, horn, or antler. Proper identification of these materials is important, as it may determine the type of care required for the object’s continued well-being.
Identification
Horn consists of the same material as hair, hooves, and fingernails. If examined closely, it resembles a mass of very hard, hair-like filaments cemented together. Horn grows around a spongy core. If the core is removed from the horn, a hollow object, such as a powder horn, can be made. Horn can also be boiled, cut, and moulded to other shapes, or used in flat sheets.
Handling
Artifacts of ivory, bone, horn, or antler should be well protected from sudden changes in temperature and relative humidity (RH) whenever they are removed from the museum. This can be done by wrapping them in unbuffered, acid-free (neutral pH) tissue paper and placing them in a sealed polyethylene bag for transportation.
Be careful when handling or cleaning these artifacts...
Storage
Store artifacts in a tightly closed display case or storage drawer to buffer them against sudden changes in temperature and RH, and shield them from dust and dirt. Storage in the dark will also protect light-sensitive dyed or painted surfaces.
Bone, ivory, and antler are rarely attacked by insects, but
horn is often seriously damaged by the larvae of carpet beetles and clothes moths. Inspect objects at least twice a year for insects and mould growth (see CCI Notes 3/1
Preventing Infestations:
Control Strategies and Detection Methods)
and 3/2 Detecting Infestations: Facility
Inspection Procedure and Checklist). Immediate attention is required if an infestation is detected.
To guard against bumping and chipping, line storage drawers and shelves with a chemically stable cushioning material such as polyethylene or polypropylene sheeting (e.g. Ethafoam or Microfoam).
Avoid using rubber-based materials for storage or packing as these can produce unnatural yellowing of ivory.
Cleaning
Ivory, bone, horn, and antler are all porous materials susceptible to staining if left in contact with corroded metals (such as copper or iron) or coloured materials. Stains of this nature should be referred to an experienced conservator for treatment. However, if the objects are in good physical condition, normal surface dirt and grime can be removed safely. A light dusting with a soft brush is often all that is necessary to keep objects clean. Use the brush to dislodge dust and debris, directing it toward a gauze-covered vacuum cleaner nozzle.
Horn is somewhat more durable than bone and ivory, and the above cleaning methods can be applied to it as well, providing the surface is intact and not delaminating. However, horn in the form of thin films (as in lanterns) can be softened very quickly by contact with water and may well be deformed; do not use water on these artifacts.
Illumination
Do not place ivory, bone, horn, and antler in bright areas, such as direct sunlight or near spotlights. Illumination should be kept below 150 lux, with the ultraviolet (UV) component restricted to 75 μW/lm. Objects that are coloured with dyes are extremely light-sensitive and should be exposed to no more than 50 lux. Limiting exhibition time will help reduce light damage, which is cumulative and irreversible. More in-depth information on light is available in
Light, Ultraviolet and Infrared. For information on measuring light levels and filtering UV radiation, refer to CCI Notes 2/4
Environmental Monitoring Kit and 2/1 Ultraviolet Filters, respectively.
Be careful when using tightly sealed display cases. The radiant heat from light sources can quickly produce very high temperatures and rapid fluctuations in RH within the case, which can damage sensitive materials. A bright light beam directed at an artifact can also raise its surface temperature. To reduce the risk of damage, maintain low light levels and use lights that emit less radiant heat.
RH and temperature
Of ivory, bone, horn, and antler, ivory is the most sensitive to changes in RH and horn is the least sensitive.
Ideally, ivory, bone, horn, and antler should be displayed and stored at a temperature not greater than 25°C and an RH in the range 45–55%. In practice, these conditions are often difficult to achieve in many Canadian museums, especially in winter. However, try to maintain as steady an RH and temperature as possible, and, most important, prevent exposure to extreme conditions or rapid fluctuations. Always keep objects away from direct sunlight, hot light sources, ventilation or heating ducts, fireplaces, the top of appliances (such as radios or television sets), exterior walls, or cold windows.
Environmental Guidelines
for Museums — Temperature and Relative Humidity (RH) provides a general introduction to CCI’s current
approach to controlling ambient RH and temperature
in museums. More information regarding RH and
temperature is available in Incorrect Relative
Humidity and Incorrect Temperature.
Repair
Broken, friable, or extremely dirty objects requiring repair, consolidation, or extensive cleaning should be referred to an experienced conservator.
Bibliography
Pedersen, M.C.
Gem and Ornamental Materials of Organic Origin. Amsterdam: Elsevier, 2004.
by Tom Stone
Originally published 1983, Revised 1988, 2010
©Minister of Public Works and Government Services Canada, 2010
Cat. No. NM 95-57/6-1-2010E
ISSN 0714-6221
Additional information is also available from Smithsonian.
