Compare and contrast a folding carton, a shipping box, and a flexible film pouch. These three types of packaging serve the same function, to contain and promote, but their materials and production processes are not the same. Paperboard creates crisp, defined panels and a print surface, corrugated provides a cushioning effect with compression strength, and film can wrap around the product and be sealed into a low-cost format. It is helpful to recognize these differences to see why package structure starts with the substrate.
Paperboard is the material of cartons, sleeves, business cards, and small display packs. It is a lightweight material that is smooth to the touch and provides a printable surface that can be decorated with detailed graphics, varnish, lamination, foil stamping, and embossing. The dieline for a paperboard carton has a set of panels, creases, tuck flaps, locks, and a glue flap. The paperboard stock has both a thickness and a grain. A coated board looks great, but a paperboard carton with heavy ink coverage and/or a crease not perpendicular to the grain may have whitening or flaking on the crease.
A corrugated box is made of one or more flutes, or layers of paper, between flat sheets of paper, and is typically associated with shipping cases, trays, inserts, and cushioning. Each layer creates an air pocket that makes the material more impact and stack resistant. A variety of flute profiles affect the thickness, rigidity, printability, and folding behavior of the board, and measurements require extra consideration because the flutes give corrugated board more bulk than paperboard.
Film is the material of flexible packaging, such as pouches, wrap, and sachets, which do not stand alone as rigid panels. Multiple layers are used to achieve specific print, sealing, strength, or barrier properties. Seal dimensions and any gussets, plus the location and orientation of the product, determine how much product can fit in the pack. A pack may have a large footprint when flat, but the seals at the ends and sides take up space that would otherwise be used for product. Film requires testing as appearance does not guarantee strength, durability, or suitability for the end use.
As you compare these materials, pick a few sample pieces from each category, then look at them. Do not attempt to classify or grade the samples; simply examine them. Try to bend the paperboard along and across its grain and push on the corrugated material; look at the corrugation between the outer liner sheets. Light should shine through the film, which should be examined for surface finish and integrity of sealing. Take note of thickness, flexibility, surface roughness and appearance, folding behavior, how the package is fastened, and the likely applications. You now have first-hand knowledge of what different material types feel and look like.
Material specifications start to break down when a decision is based on a visual or tactile quality, such as “needs a shiny finish”. Some corrugated packaging is very rigid and will not work with heavy loads. A film package should be made of very high quality components to seal correctly. Many product attributes must be considered in determining the appropriate substrate material, including, but not limited to, product weight and dimensions, water, abrasion and drop test, retail storage and display environment, printing requirements, sealing options, and filling, packaging, and handling speeds. Material claims also should not be assumed to include end-of-life options, such as recycling, without verification of the end-use environment and packaging components.
When evaluating a package, consider what is the job requirement of the substrate. Must it be stiff, shock-absorbent, creased into a shape, sealed, printed to high standards, or all of the above? The answer to those questions will not immediately point to an appropriate substrate material, but it will give the designer a much more accurate comparison with which to start making a recommendation and selecting a substrate for testing.