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
  • alkyd
  • 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.


Table 9. Two crating alternatives for in-house construction.
Crate typeDescriptionApplications


Triwall crate

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.


Basic wood shipping crate

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.).
For heavy loads use thicker plywood for the base and wall panels.

 

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”.
Figure 3. Consider pump truck access when building or specifying large or heavy crates. Allow a skid spacing width (W) of 710 mm (28 in.) for wide trucks and of 580 mm (23 in.) for narrow trucks. Allow a width (w) of 200 mm (8 in.) for tines. Skids must raise crates to a height (h) of 100 mm (4 in.) above ground level for easy access.

Basic Wood Shipping Crate

Figure 4. 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

  1. Construct the panels first. Apply glue, position the cleats on the panels, and tack them in place with staples or nails at the ends not closer than 10 mm (3/8 in.) to the edge of the cleat (consult Figure 5a).
  2. Turn the panel over and fasten the cleat from the panel side with two staggered rows of fasteners spaced about 150 mm (6 in.) apart and not closer than 10 mm (3/8 in.) to the edge of the cleat (consult Figure 5b).

If nails are used, ensure that they are 12 mmin.) longer than the thickness of the panel plus the cleat. Drive them from the cleat side and bend them over. If staples are used, choose divergent staples (designed for increased holding power) and insert them on a 45° angle as shown.

  1. Assemble the panels with screws or staples. Ensure the fasteners are long enough to penetrate the plywood and anchor them securely into the cleats. Place fasteners in rows with about 150 mm (6 in.) between them. If cleats are more than 80 mm (2 ¼ in.) wide, use two fasteners at the ends.
  2. If the crate will be used for only one or a few shipments, screws can be used as a simple means of attaching the cover. However, if the crate will be used for multiple shipments, use captive nuts or latches to attach the cover.

Edge cleats can be added to the inside of the cover (left) to improve the case seal details and to increase the crate's resistance to deformation.

Figure 5. Handles and skids may be added as shown in Figure 4.
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