Society for the Preservation of Natural History Collections September 2019 - 31

Features
The highest tray can now be safely removed and replaced by
a person of average height without the use of ladders or stools
(Fig. 8).

Fig. 7. A completed section of the ANSP collection. Note:
the bottom shelf is tall enough to take gallon jars, two more
shelves have been added, and former spacing is visible at
the far end.

system the front wall of each tray performs the same function
and prevents accidental knock-offs, but the whole tray might
still slide forwards during violent seismic events. In addition,
as the trays are to be slid on and off the shelves in regular use,
we felt that a shelf liner would provide some smooth drag
while protecting the powder coating and the shelf's painted
surface from scratching and scuffing. The liner should offer
enough friction to prevent the trays sliding under even strong
lateral movement but not make them too difficult to extract.
At the same time, it should be at least as fire resistant as the
closures of the jars, the only other plastic in the room. The
material finally chosen was Sekisui Kydex™ (https://sekisuispi.com/), a flexible PVC/Acrylic sheet used in aircraft
interiors. Its UL-94 classification is "V-0" or Low Flammability; its flash point is 390°C (734°F), well above that of
the polypropylene jar lids in the collection (335°C / 635°F),
and it offers the right balance of smoothness and resistance
to sliding. Of other materials, acrylonitrile butadiene styrene
(ABS) was rejected for its incompatibility with ethanol, and
high-pressure laminate (e.g., Formica) for its weight and low
fracture resistance. The Kydex liners were cut at the factory
to fit the shelves exactly and are retained by the L-section
upright at each corner (Fig. 6), thus requiring no adhesives.
Advantages
The system of trays has allowed the existing racking to be
configured more efficiently (Fig. 7). Removing the need to
reach in for the rearmost jars allowed the headroom to be
reduced to just slightly more than the height of the tallest jar
used. As a result, two more shelves can be inserted in each
vertical set and thus approximately 25% more containers
can safely occupy the same space. This compression also
allowed us to stop using the topmost shelf, which could thus
be removed to allow better lighting and sprinkler penetration.

One of the major advantages of this tray design is that making it requires only machinery and finishing that is normal in
a sheet metal works. Prototypes were ordered from three U.S.
companies chosen at random from those listed on the Internet
as general sheet metal fabricators and all three produced dimensionally accurate finished trays of equal and fully acceptable quality from the same drawing (Fig. 3). Though there
were variations in the quoted unit price, these largely reflected differing shipping costs. Reproducibility is an important
consideration in the design of museum equipment as it allows
institutions to more economically upgrade their equipment
and potentially to strengthen community networks by working with local manufacturers.
Perhaps the most significant gain from the adoption of this
system is the shortening of maintenance cycles associated
with checking alcohol levels. By pulling a tray out and looking at both sides it is possible to check the condition of every
lot in it at a glance. At the ANSP it is estimated that this will
have reduced the time one person takes to assess the condition of the entire mollusk collection from more than a year to
a few weeks. If a failing closure is found, the entire tray can
be quickly carried to a lab, the fault remedied and the tray
returned to its correct position in short order. The initial cost

Fig. 8. Handling the new trays is easy and safe.

of the system is thus ameliorated by very significant savings
in labor. In addition, the trays are far more user-friendly to
handle than individual jars, reducing the likelihood of lots
being accidentally overlooked through fatigue.
Further considerations
Under some fire codes, shelving systems in rooms with sprinSeptember 2019 * 31

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Society for the Preservation of Natural History Collections September 2019

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