Oversize
Anthropology Collections Rest Easily
at the Smithsonian's Museum Support Center
 |
Plaster cast of an Olmec head weighing 2161 lbs.
|
 |
| Badly damaged plaster cast of Greek/Roman sculpture requiring additional stabilizing bracing. 656 lbs. |
Forty-foot
totem poles from the Northwest Coast, stone carvings from Easter Island,
unwieldly plaster sculptures, canoes, and rickshaws are some of more than
600 oversized objects that have been safely moved from outmoded storage
in the National Museum of Natural History to safe, environmentally controlled
and palletized storage at the Museum Support Center in Suitland, MD, thanks
to an innovative collaboration between the museum's Department of Anthropology
and the museum's Move Office. Although the use of palletized storage in
museums was not new when we began the move project, it represented a new
set of challenges for the Department of Anthropology.
The storage area known as Pod 4 would provide continuous rows of 2', 4' and 8' deep cantelevered open racking from floor to ceiling (22 feet high) allowing palletized objects to be moved and placed in the racking using a forklift.
Greta Hansen, the department's project conservator, and Deb Hull-Walski, the department's collections manager, devised a set of basic storage requirements that addressed collections concerns. These included:
- Sturdy, durable, and lightweight construction of the pallets able to withstand minor dropping and jarring
- Unobtrusive open framing or bracing to secure objects on pallets
- Ease of access and retrieval of objects. Objects should be visually accessible to researchers without the need to remove parts of the support system
- Durable, easily attached coverings to provide dust, light and water protection for each object
- Archival quality support materials for anything that comes in contact with objects
- Proper cushioning of each object must be provided in order to withstand a 36 inch drop.
Conservator Sunae Park Evans assisted Greta Hansen in the early stages of the development and the first two years of the project's implementation. Initially we investigated the use of the traditional wooden pallet. We knew such pallets would be acidic by nature, bulky and heavy, and that they tended to be dirty and prone to pest problems. Additionally, the Smithsonian Safety Office required that any wood used as a pallet material must be fire retardant. We turned to the Smithsonian Center for Materials Research and Education to aid in the review of the issues related to the nature of wood and fire retardant-treated wooden pallets.
Senior SCMRE furniture conservators Don Williams and Mel Wachoviak confirmed our concerns and strongly recommended against their use on the grounds that the chemicals used as fire retardants were very corrosive to metal fasteners used to construct the pallets and would compromise their integrity over time. The fire retardant chemicals also are water soluble, and that in the event of a water disaster not only would cleanup be hazardous but objects would be seriously compromised as well. Aluminum pallets were considered as their use would adequately address the requirements for a lightweight and sturdy construction material. The advice of SCMRE mechanical engineer, Marion Mecklenburg, was sought to address the issues of actual specifications for these pallets such as aluminum grade, gauge, and strength as well as the proper loading, point pressure, and deflection. Ultimately the pallets were custom sized for specific objects, engineered for specific loading, and designed for both forklift and pallet jack access. The aluminum pallets were purchased from Cherry’s Industrial Equipment Corporation and were made from 6105-T6 alloy, were 100% welded and sealed, and configured with 4-way entry. In addition, lightweight aluminum stock (1/8” thick, 6063-T52 alloy) was used to fabricate unobtrusive framing and bracing to secure objects on the pallets, thereby allowing for visual access to objects.
 |
Algonquin
birchbark canoe weighing 42 lbs. |
Other materials used in the fabrication of support systems for objects are widely known by conservators and collections staffs and meet archival standards. These include Ethafoam™ 220 from the Dow Chemical Company, polyester pongee fabric, Pellon®, muslin, polyester batting, polyester web strapping and Jet Melt™ #3764-TC adhesive (ethylene-vinyl acetate polymer with hydrocarbon resin, polyethylene and paraffin waxes) from the 3M Corporation. However, two materials proved problematic. Finding an adhesive that would adhere Ethafoam™ to aluminum and would meet our purity standards was challenging. After numerous experiments and consultations with industry representatives we chose High Strength 90 adhesive from 3M Corporation. According to a 3M representative, it is a combination of nitrile and neoprene rubbers and was considered to have relatively good longevity. Because we had no prior experience with its use, all materials secured with this adhesive were additionally fixed in place by a mechanical means such as pop rivets or metal reinforcement strips or cable ties. This extra measure was considered essential because adhesive failure could prove hazardous both to objects and forklift operators when removing pallets from the racking system, particularly unevenly weighted pallets or those stored on the upper levels.
The
second problematic material was the covering material. The material needed
to be breathable, and provide light and dust protection to objects. It
also had to be water resistant because of the potential of water leaks
from the roof, air handlers, and accidental discharge from sprinkler heads.
The Smithsonian Safety Office also required that it be fire resistant.
This complicated our search because we desired a material that would not
melt or drip (damaging objects) in a fire. After much research an undyed,
woven Nomex® fabric (style # 90438 from Safety Components Fabric Technologies,
Inc) made by the DuPont Company was selected for the drape material. This
had to be additionally treated with a water repellent (durable water repellant
finish) because without it, Nomex® absorbs water readily. Read
more ....
Continue
to Part Two
Return to the Anthropology Conservation Laboratory
Research | Online Exhibits | Teaching & Learning | Archives | Collections