Step 4. Recognize the benefits of primary packaging (e.g. mounts, protective wrapping)

Primary packaging ranges from simple wrapping to elaborate transit mounts that can restrain an object in all directions. This basic form of packaging is not intended to adequately control shock or vibration during shipment. However, it can and does make a difficult object easier to handle and pack and can also reduce an object’s overall susceptibility to force. This not only reduces dependence on the packing system during shipment, it also makes the object less susceptible to damage when it is handled in-house. Table 5 provides some examples of primary packaging treatments.

Table 5. Primary packaging makes packing easier and can make an important contribution to the overall effectiveness of a protective package.
ExampleFunction

Basic wrapping with an interleaf material followed by polyethylene (e.g. wrapping paintings as outlined in CCI Notes 10/16).

Avoids punctures, dents, and abrasion, and protects against minor impact.

A reasonably tight-fitting polyethylene wrapping that encloses a cardboard-covered painting or painting/frame can buffer RH changes and protect the painting surface.

Armatures or other provisions to support an item with fragile surfaces at non-critical areas.

Avoids direct contact between the fragile item surfaces and the cushioning material.

Avoids abrasion of a fragile surface against the cushioning material.

Provides an intermediate structure or form that can easily be cushioned.

Mummy wrap for a fragile surface (use unbuffered tissue paper made of abaca fibres).

Gently protects a fragile surface enabling the object to be cushioned directly (not recommended for paintings).

Negative mount (a form fitting cut-out in a firm foam material such as polyethylene foam). An interleave material may be used between the object and the mount to improve the fit of the mount or to protect fragile object surfaces.

Creates a lower load per unit area than do individual support points, which is especially important for fragile object surfaces.

Allows for voids to be carved around small projections that are easily damaged when wrapping/unwrapping or packing/unpacking.

Because the object/mount combination is stiff compared to the cushioning system, it limits movement along the object/mount interface and associated problems such as abrasion.

Hard objects such as bottles or dishes packed together in a box and separated from each other and the inner box surfaces with an interleave material such as thin cardboard or thin sheets of polyethylene foam.

Avoids impact between hard objects.

Several items firmly packed together in a container with suitable interleaves between them, or partitions for heavy items, to ensure that they do not move relative to each other.

Enables multiple items to be protected with one cushioning system.

Simplifies the design of the cushioning material.

Assures good cushion performance.

Allows for economical use of expensive cushion materials.

Filling/support for thin-walled items such as ethnographic objects (e.g. hats, boxes).

Restrains and immobilizes fragile items and helps them retain their shape during shipment.

Primary packaging can also serve as a control measure against incorrect RH as well as dust, insects, water, and contact with incompatible materials. Table 6 provides some examples of useful primary packaging materials, although many more are available.

Table 6. A collection of useful primary packaging materials and their applications.
MaterialDescriptionApplications

Polyethylene sheet (HDPE)

High-density polyethylene.
Higher density than ordinary polyethylene sheet, offers better protection with thinner films.
Few release agents and plasticizers.
Available as small food-grade bags or in larger rolls from bag manufacturers.
Can be found in home improvement centres where it is sold as painters plastic.

Wrapping irregular shapes (because it is thinner, smoother, and more flexible than low density sheet, it is better able to conform to irregular shapes without excess bulk or folds).

Polyethylene sheet (LDPE)

Low-density polyethylene sheet.
Chemically stable, but talc or other release agents may be present and surface may also have an oily residue.

Wrapping paintings (with an interleaf material between the polyethylene and the painting) and inner boxes.

Teflon thread seal tape

Synthetic fluoropolymer made by Dupont.
Chemically stable and non-toxic.
Very stretchable and able to conform to various shapes.
Conforms easily to cavity shapes in mounts without adding bulk.

Covering foam pads.
Use with polyester batting to line cavities in mounts.

Aluminum-coated polyethylene (Marvelseal 360)

Nylon-coated aluminum barrier bonded to polyethylene.
Effectively blocks passage of water, gases, and pollutants.

Lining the interior of shipping crates – especially if long storage periods are anticipated.
Making bags to encapsulate objects.
Lining interior cases of double case packages.

Unbuffered abaca tissue paper

Unbuffered long-fibred tissues made from abaca fibres similar to Japanese paper.
Expensive.

Cushioning very delicate materials.
Interleaving delicate items where it is necessary to conform to intricate forms.
“Mummy wrapping” objects with fragile surfaces by repeatedly wrapping the item with thin strips.

Tyvek soft structure fabric

Spun-bonded high-density polyethylene fibres woven into a fabric.
Lightweight, chemically stable, non-abrasive, and tear resistant.
Heat-weldable to itself or it can be sewn.

Placing over polyester batting material to form pads.
Interleaving material for contouring cavities and covering foam pads.

Cross-linked polyethylene sheet
(Volara)

Made by Voltek (Volara is the brand name of Voltek’s closed-cell polyethylene foam).
Smooth and non-abrading.
Common density is 33 kg/m3 (2 pcf).
Thickness range is 3–12 mm (1/8 – ½ in.); commonly used thickness is 6 mm (1/4 in.).

Heat-welding to polyethylene foam mounts to provide a non-abrasive surface at contact points.
Lining cases and crates.
Padding small unframed paintings in transit frames.

Stretch wrap

Linear low-density polyethylene (LLDPE).
Flexible; elongates to wrap around shapes.
Best used with a barrier material.
Comes in roll widths of 50 mm (2 in.) to 760 mm (30 in.).
Can be obtained from moving or packing material supply outlets.

Holding delicate objects or object parts in place.
Securing boxes together.
Sealing packages against water, pests, etc.

Polyethylene foam sheet

Chemically stable closed-cell polyethylene foam; typical trade names are Ethafoam and Polyplank.
Easy to work with; can be heat-welded to itself.
Most commonly used density is 33 kg/m3 (2 pcf).
A popular thickness is 50 mm (2 in.).

Making long-term storage mounts and transit mounts.

Acid-free tissue, unbuffered

Acid-free tissue made from high-quality pulp that does not contain lignin.

Wrapping metals to avoid possible condensation.
Wrapping thin organic materials to help stabilize humidity after they are enclosed.

Polyester quilt batting

Sold in rolls to make quilts.
Can be layered.

Padding uneven or complex surfaces.

Extruded polystyrene foam plank (Styrofoam)

Typically sold for insulation purposes.
Limited application for cushioning as it is non-resilient (does not return to its original shape after impact).
Excellent insulator.
Chemically stable.

Lining the interior of shipping cases or interior cases of double case packages to provide temperature buffering.

* pcf = pounds per cubic foot.

For additional material choices and guidelines on their use, see Mount-making for Museum Objects, Second Edition, and Technical Bulletin 14 Working with Polyethylene Foam and Fluted Plastic Sheet. The Packing, Art handling & Crating Information Network (PACIN) site (consult the link at the end of this document) also has an extensive material list. However, although many choices exist, most packers have their own short list of preferred materials.

Temperature and Humidity

Temperature buffering during shipment can be achieved by lining the inside of a shipping container, or the inside surfaces of an inner case of a double case system (consult Figure 1), with polystyrene plank insulation. Note that cushioning material is also a good insulator, so items completely wrapped in cushioning material will also be buffered from temperature changes.

Figure 1. A double case package consisting of an inner box that
is supported on corner pad cushions and placed in an outer crate.

Humidity control for organic materials during shipment can be achieved by wrapping them with an interleaf material and then with a polyethylene sheet, and closing the seams with tape. Note that this treatment is effective only if the contained air space around the object is minimal — which means that the object should be wrapped fairly closely (although it is not necessary to achieve a really tight fit). The wrapped object can then be packed into the inner case of a double case package.

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