Storage System for Large Objects Using Form-fitted Support Pallets and Pallet Racking
Pallets customized with form-fitted mounts can provide maximum support for large fragile specimens, preventing them from being abraded on shelving, or being bumped into one another. Access to even the heaviest specimens is relatively easy and safe using a forklift, no matter how high the shelf is.
In addition, storage can be organized following a logical sequence rather than simply keeping the heaviest specimens close to the floor. However, for safety in earthquake-prone areas, the heaviest specimens should be kept as low to the floor as possible. Relatively inexpensive pallet rack storage systems can be designed to take advantage of all the available height of a room, thus maximizing the use of space.
Gerald R. Fitzgerald
Canadian Museum of Nature
Box 3443, Station D
Canada K1P 6P4
Tel (613) 954-0358
Fax (613) 954-6439
Dan S. Chaney
Department of Paleobiology
National Mus. of Natural History
Washington, DC 20560 USA
Tel (202) 357-4479
Fax (202) 786-2832
Kieran M. Shepherd
Canadian Museum of Nature
Box 3443, Station D
Canada K1P 6P4
Tel (613) 954-0360
Fax (613) 954-4724
Gerald R. Fitzgerald
Fig. 2: Karen Ackoff after
sketches by Gerald R. Fitzgerald
Fig. 4: Alexia S. Scott after
sketches by Kieran Shepherd
Standard or custom-sized pallets are fitted with gypsum cement and fiberglass mat, or plaster of paris and burlap half-shell forms specially created for individual specimens or for a group of specimens. These form-fitted support pallets are easily and safely moved with a forklift
Figure 1. Wooly mammoth skull on a form-fitted pallet. Note the polyethylene foam padding in the form, the
attachment of the form to the pallet using excelsior and plaster, the prominent specimen number on the
front of the pallet, and the dust cover that has been rolled back for the photograph.
Materials Tools Supplies
- Commercial warehouse pallet racking/shelving
- Continuous monofilament random glass fiber mat, 15mil
- Gypsum cement or dental stone
- Heavy duty scissors
- Lumber, 2in x 4in or metal box stock or slot angle steel
- Mixing bowl
- Nails or nuts and bolts or screws
- Paper towels or blank newsprint paper
- pH neutral tissue paper
- Plywood, 3/4in or 5/8in
- Polyethylene foam sheeting, 1/8 – 1/4in thick
- Polyethylene sheeting, 4-6mil
- Sand bags
- Burlap strips
- Plaster of Paris, quick setting
Simple pallets can be constructed by screwing or nailing a piece of a 5/8in or 3/4in thick plywood of the required dimensions to 2in x 4in lumber skids, or by bolting it to metal box or metal slot angle to make skids. The skids are fastened near the edge for increased strength and to provide space for the forks of the lift. The inset along the edge provides finger holds should they be needed at any time.
Customized half-shell forms
The customized half-shell forms, for all but the largest specimens, are made easily on a sturdy table. The entire procedure is best done by more than one person due to the weight of the specimens and palletized form.
- Pad the table top, or section of the floor, and cover it with a piece of polyethylene sheeting.
- Mark the polyethylene sheeting with the outside dimensions of the pallets.
- Lay the specimens within the limits of the desired pallet.
- Pad and provide temporary support with sandbags. Careful placement of the specimens will maximize the number that will fit on a pallet. Note that the side of the specimen that is now up will be the side which ultimately will be down when the specimen is in final position on the pallet. Consideration must be given to protruding areas of specimens that may become caught in the form-fitted supports, and to the location of the specimens’ catalogue numbers. If the catalogue number is obscured by the form, it may be necessary to mark the number on a given specimen a second time and in a different location, as it is an advantage to have the number visible when the specimen is in place on the form (Fig. 2).
Figure 2. Cross section through a form-fitted pallet.
- If required, place padding over the specimen as well. generally, padding, is used only for heavy and simply-shaped specimens, as padding makes it difficult to form the support to the contours of the specimens.
- Cover the specimens with a piece of polyethylene sheeting to protect the specimen while constructing the half-shell support form.
- Place a layer of wet paper towels or blank newsprint paper over the polyethylene and gently pat it to conform to the upper surface of the specimen without creating undercuts. Alternately, polyethylene foam sheeting can be left in the form.
- Mix gypsum cement or dental stone with water to a thick creamy consistency.
- Cut strips of glass fiber mat with their size being dependent on the size of the support required. Experience has proven that smaller strips are preferred.
- Lay strips of continuous monofilament glass fiber mat one at a time on the damp paper over the specimen(s).
- Brush the gypsum cement onto the glass fiber, gently shaping the glass fiber to the specimen. Four to six layers of 15mil thick glass fiber are required, depending on the weight of the specimen and the thickness of the gypsum cement mixture.
The following method also works well:
Dip the strips of glass fiber in a thin slurry of gypsum cement or dental stone and then apply them to the specimen.
Great care must be taken to avoid undercutting the surface with the matting, otherwise removal of the form-fitted supports will be difficult and could damage the specimen (Fig. 2).
- Allow the gypsum cement to set. While still damp, trim off excess material around the edge.
- Remove the form-fitted, half-shell support(s) from the specimen and turn it right side up.
- Attach the form-fitted support to the wooden pallet using gypsum cement and wadded or folded glass fiber mat. Blocks of wood roughly cut to fit the contours of the form-fitted support also can be placed under the form to level it and to provide support on the pallet.
- Note the number, location and orientation of the specimen(s) in the form-fitted support(s), and allow the support(s) to thoroughly dry.
- Trace the outline of each specimen onto the form-fitted support(s) and write the corresponding specimen catalogue number in each position, so that people using the collection can easily return a specimen to its proper position. This is important as improperly placed specimens are more likely to be broken.
- Fasten a label with the catalogue number(s) of the specimen(s) in large bold numbers to the front of the pallet for quick reference.
- Cover with a polyethylene dust cover (Figs. 1).
The first step is to design the layout of the room. Considerations include forklift access, easy movement of specimens, location of supporting uprights, length of shelf supporting beams, and weight of loads the shelves will carry. It is best to use a standard beam length, unless configuration of the room is such that this would result in wasted space (Fig. 3).
Figure 3. A manually pushed forklift can be used to access palletized specimens. Note the palletized
crates on the top of the shelves and the palletized field blocks on the shelves at the extreme left. All
pallets and crates are numbered so that the specimen numbers can be read from a distance.
There is a trade-off between the number of uprights and the length of the shelf support beams. The longer the beam, the thicker the beam must be. This results in loss of usable space. If only partial oversized storage is required, it is preferable to put the longer beams in one single area rather than throughout the system.
The shelf support beams should be fitted with a metal lip on the inside edge, unlike standard pallet beams, to allow for a heavy plywood shelf to be fitted between the beams. This provides added protection against pieces falling through and damaging specimens below.
Individual form-fitted support pallets can hold a single large specimen, several pieces of the same specimen or several smaller but heavy specimens which have similar storage condition requirements or some other aspect in common, e.g., same locality.
For the most part, standardized pallets that are multiples of the shelving dimensions should be used. It is advantageous to use more than one standard size pallet and odd-sized pallets will be necessary for some specimens.
An important consideration in selecting the standard pallet size for your storage area is the turning radius of the fork lift when carrying a pallet. When the pallet racks are assembled, shelf-support beams should be installed at variable heights to suit the specimens rather than at a single standard height.
The shelf interval must allow for the lifting of the pallet to remove it from the shelf without hitting the bottom of the overlying shelf or supporting beam. This will require some preplanning but will result in significant space saving.
When choosing the materials to create the form, the following considerations must be weighed:
3 Burlap may be used instead of glass fiber, but it holds a tremendous amount of water, thus requiring an extended drying time before it can be used. Thus, efforts should be made to obtain and use the fiberglass and gypsum cement, but failing this, it is better to palletize the specimens that require this protection than to wait.
3 Gypsum, a slow setting plaster (50-70 minutes), is more expensive per 100lbs than plaster of Paris.
3 Gypsum is stronger than plaster of Paris; a smaller quantity is required to achieve the necessary strength, so it is cost effective.
3 Fiberglass mat is not affected by rodents and other pests, and it is not biodegradable. However, it is more expensive than burlap.
This technique can be used to make
supports for small specimens. Small specimens can be wrapped in very thin polyethylene and placed in a sand box.
The specimen and the sand box are then covered with another thin sheet of polyethylene. Forms can then be laid up over the specimen following the previously described technique, except that they need not be as thick (Fig. 4, top).
After the form dries, it should be lined with pH neutral tissue before the specimen is placed in the form (Fig. 4, bottom). Small specimens in these light and strong supports can be stored in specimen cabinets on polyethylene foam sheeting.
Figure 4. top, Specimen is covered with polyethylene sheeting , and a fiber glass mat impregnated with dental plaster is applied. All
work is carried out in a sand box, with a protective layer of polyethylene sheeting between the specimen and the sand.