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WASHINGTON,
DC—The interior of a new museum store at the Smithsonian
Institution's Kenneth E. Behring Hall of Mammals complements
the exhibition theme using a landscape of slatwall graduated
from top to bottom in orange-gold, reddish rust, and
dark brown earth tones, and several hundred shelves
that were membrane-pressed and miter-folded using a
protective thermoplastic material in ivory color, creating
seamless, drop-front edges adorned with 3D patterns
of tiger, giraffe, jaguar, and zebra hides.
Alternative sought for laminated, painted, glazed shelving
Al Mercogliano, designer/planner for the Smithsonian
Business Ventures project, decided against glass, HPL,
or painted wood shelves because none withstood high
visitor traffic in other Smithsonian museum stores without
showing signs of wear.
"Glass shelving quickly scratched, cracked, or
chipped due to the volume of visitors handling the merchandise.
We liked the look of light filtering through glass,
but the damage necessitated frequent replacements,"
he says. "Painted wood shelving held up poorly
and scratched easily, while shelving surfaced with high-pressure
laminates chipped and cracked. Children would pick at
the edgebanding and eventually peel it off."
Mercogliano found a solution in the form of membrane
pressing and miter folding of heavy-gauge, impact-resistant
thermoplastic sheet. The process not only upgraded durability
of the shelving, but allowed the reproduction of 3D
mammal skin patterns not achievable using traditional
materials or surfacing techniques.
Design
and production of membrane-pressed shelving
Mercogliano based his shelving design on the 3D capabilities
offered by membrane pressing and the seamless outside
edges produced by miter folding. The final configuration
incorporated rounded corners for safety and durability,
a drop-front edge for strength and visual impact, and
3D mammal skin patterns for continuity with the exhibit
theme.
For the surfacing material, he selected Kydex“
6200 sheet, a proprietary, fire-retardant thermoplastic
alloy offering Notched Izod impact resistance of 3.5
ft.-lb./in. (187 J/m) (ASTM D-276), tensile strength
of 6000 psi (41 MP/a) (ASTM D-638), Rockwell Hardness
of 98 (ASTM D-785), and heat deflection temperature
of 172∞F at 264 psi (78∞C at 1.8 MP/a) (ASTM
D-785). He specified the sheet in 0.028-in. (0.7mm)
thickness to withstand the rigors of high traffic, with
a "Haircell" surface texture to resemble animal
hide and an integral ivory color to render scratches
or gouges from severe damage inconspicuous.
He contracted with East Coast Cabinets Inc. in Pennsauken,
N.J., to fabricate the shelving. Using dimensional drawings
and mammal skin artwork provided, the company created
a program for CNC routing of 3D skin patterns into the
surface of the 0.75-in. (190mm) MDF substrate and of
the shelving perimeter.
All top and side surfaces of the machined substrate
were sprayed with adhesive, then placed in a membrane-pressing
machine that heats the thermoplastic sheet and fuses
it to the top and sides of the routed substrate using
a combination of physical pressure above the sheet and
vacuum below. After the part cools and excess sheet
is trimmed from its bottom edge, the back side is CNC-routed
with a 90∞ V-groove miter, then sprayed with adhesive
and closed using the film as a hinge, forming the sculpted,
drop-front edge of the completed shelf (see left
sidebar, "Membrane pressing").
"The finished miter-folded shelf is solid as a
rock," says Joe Romano, president of East Coast
Cabinets. "Carving these patterns into solid wood
would cost a fortune and would lack the durability provided
by the protective surface cladding.”
The most vulnerable areas of a membrane-pressed component
in high-traffic environments are the corners, edges,
and high spotsæthe same areas where heated thermoplastic
sheet tends to thin as it conforms to the contours of
the routed substrate, reducing impact resistance where
it is needed most. The durability of a membrane-pressed
component is therefore related not only to its mechanical
properties at room temperature, but its ability to resist
thinning at stretch points during forming at temperatures
of 325-392°F (163-200°C).
"The Kydex material is formulated for thermoforming
applications, and we found it effective at maintaining
a uniform wall thickness, confirmed by cross-section
quality checks of membrane-pressed parts. Although it's
a rigid, heavy-gauge sheet product, extensibility is
sufficient to form a sharp 90-degree outside corner
during miter folding without heating of the sheet at
the fold point," says Romano
New
look expected to keep looking new
According to Mercogliano, the store's new look is harmonious
with that of the mammal exhibit owing in part to the
3D organic shapes achieved by membrane pressing of the
shelving. With the added durability of rounded corners
and protective cladding, the shelving will continue
to look new longer than it could if conventional materials
and manufacturing techniques had been used, he anticipates.
The Smithsonian Institution's Kenneth E. Behring Hall
of Mammals, 25,000-sq.-ft. interactive hall, features
274 taxidermied mounts and mammal fossils telling the
story of the processes by which mammals arose and continue
to adapt.
East Coast Cabinets Inc. is a wholesale manufacturer
and subcontractor for millwork, exhibits, and display
houses.
Kydex sheet is a proprietary thermoplastic alloy produced
in 40 grades, 10 surface textures, and 2,500 colors
for membrane-pressing, thermoforming, laminating and
fabricating applications to ISO 9002 and 14001 quality
standards by Kleerdex
Co.
CONTACT:
Kleerdex Co.
6685 Low St.
Bloomsburg, PA 17815
570-387-6997
www.kydex.com
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Bloomsburg, Pa
