Step 6. Find or construct good shipping crates
Shipping crates are the first line of defence against shipping hazards. While it is easy to find good woodworkers, experienced crate builders are less common. A commercially fabricated crate that is built according established industrial standards can be a good investment.
Two types of shipping crates can easily be constructed in-house: a triwall crate and a basic wood crate. Construction details for triwall crates are published in CCI Notes 1/4. Construction and assembly details for wood crates are presented below.
The panels of wood crates should be at least 9.5 mm (3/8 in.) thick. Many builders prefer to use thicker wood (12 mm, ½ in.) because the thicker sheets are flatter and easier to work with and the cost difference is small.
Features such as handles and skids can improve the ease of moving crates by manual and mechanical means, and careful handle positioning can reduce hazards by minimizing the height that a package is raised during manual handling.
For added protection, a layer of aluminum-coated polyethylene (e.g. Marvelseal) can be bonded to the case interior with an ordinary iron. This layer will:
- block the entry of water
- provide a barrier against organic compounds released by the wood
- enable the crate to be stored in uncontrolled environments
- allow cushioning material to slide easily into the case interior
- improve the thermal performance of the crate
Painting the case interior provides a lower cost alternative to Marvelseal, and is advisable if the contents will be stored inside the case for long periods of time. The following paints are suitable for this purpose:
- acrylic latex paint
- acrylic–urethane emulsion paint
- 2-part epoxy or 2-part polyurethane
- moisture-cured polyurethane
Note that these paints will need to dry thoroughly (4 weeks is recommended) before the case is used.
Some paints and coatings should never be used inside shipping crates as they give off compounds that could react with artifact materials. Unless the package is a double case system, avoid using any coatings formed by oxidative polymerization. These include:
- oil-based paint
- 1-part epoxy
- oil-modified polyurethane
The case interior may be left uncovered/unpainted if the objects placed inside it are wrapped and will not be stored in the case for long periods of time. However, for cases with uncovered/unpainted interiors, good construction detailing is essential to prevent the ingress of water, pests, or other agents.
Any paint or coating can be applied to the exterior of the shipping case.
Triple wall corrugated cardboard with softwood framing. Detailed instructions for the triwall case are available in CCI Notes 1/4. Construction time can be as little as 20 minutes. Triwall crates are lightweight and surprisingly strong.
Local moves, long distance moves with high-quality transport.
Plywood (sanded one side or sanded two sides), thickness of 9, 12, or 18 mm (3/8, ½, or ¾ in.), with 19 × 64 mm (1 × 3) or 19 × 80 mm (1 × 4) cleats (framing). Handles and skids can be added. Design can be modified into other forms such as boxes.
A strong case suitable for domestic and international shipments of loads up to 450 kg (1000 lb.).
N.B.: Wood packaging shipped to international destinations other than the United States may be regulated to avoid the spread of insect species that could harm agriculture and forestry industries. At the time of writing, there are no restrictions on the use of manufactured woods such as plywood, particle board, and wafer board; however, package components made of softwood lumber are subject to some regulations. Current information can be obtained from the Canadian Food Inspection Agency, which administers the Canadian Wood Packaging Certification Program (consult link at the end of this document).
Features of a Good Crate
- Handles positioned for ease of handling and to minimize the height that the crate must be raised (ground to hand distance for standing male/female is approximately 825 mm/780 mm).
- Skids to keep the case off the ground and permit easy access for moving equipment if the case is heavy.
- Screw or latch closures.
- Recessed hardware that won’t break off.
- Good appearance.
- Discrete labeling as “Fragile” or “Handle with Care”. Do not label as “Art”.
Basic Wood Shipping Crate
Figure 4 illustrates how the panels of a basic wood shipping crate are constructed, and how they are assembled to form the finished crate.
The lapped corner construction (detail A) adds substantial strength to the crate.
The large following image shows the crate in a tall narrow orientation that would be suitable for paintings. The crate can be changed into a box by turning it on its back panel (opposite the removable cover shown) and relocating the skids. The result is shown in the lower left image.
Constructing a Basic Wood Shipping Crate
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