Ask most people about packaging and they picture the outside of the box: the size, the print, the strength of the walls. But for manufacturers and distributors that ship many items per case, the components inside the box often matter just as much. Partitions, pads, and die cuts keep products separated, organized, and supported from the packing line through distribution.
This guide walks through the main types of corrugated interior packaging, the material choices behind them, and what to consider when sourcing them, whether you are a brand owner packing your own products or a box plant serving customers.
Why interior packaging deserves attention
A well-built shipping container is only part of the picture. If the items inside can shift and rub against one another, finished surfaces, labels, and fragile materials are exposed to contact during handling. Interior packaging gives each product a defined place in the case and adds structure to the packed unit.
Interior packaging also affects the packing operation itself. Components that fit the product and the packing method well can make cases easier to load, while poorly matched inserts can slow a line down. That is why it pays to think about interior packaging as part of the overall packaging design rather than an add-on.
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Corrugated partitions
Partitions are the most recognizable form of interior packaging. A partition is a set of interlocking board strips that forms a grid of individual cells inside a case. They are used for products shipped many to a case, such as glass bottles, jars, glassware, candles, cosmetics, and small components.
The value of a partition comes from its fit. Cell dimensions and partition configuration should be evaluated against the product dimensions, packing requirements, and overall packaging application. Suitability for another product should be evaluated rather than assumed. Two products that look alike may still need different cell sizes, strip heights, or board grades.
Specialty manufacturers build partitions around each customer’s product instead of offering a one-size-fits-all grid. Great American Paper corrugated partitions, for instance, are customized to the customer’s product and application.
Corrugated pads
Pads are flat pieces of board that work alongside partitions or on their own. They come in more forms than many buyers expect, including supportive pads, layer pads, pizza and cake circles, small slip sheets, scored pads, and box liners.
Each serves a different purpose. Layer pads separate tiers of stacked product. Bottom and top pads give the case a flat, even surface at each end. Scored pads can be folded to fit a specific space, and box liners line the inside walls of a container. Circles support round products such as baked goods. Choosing the right pad depends on the product, how it is stacked, and what surfaces need protecting.
Corrugated die cuts
Some products do not fit neatly into a square cell or onto a flat pad. Die cuts are pieces of board cut to a specific profile, which makes them useful for irregular shapes, custom inserts, and specialized supports. Common examples include corrugated circles and U-shaped inserts, along with other custom shapes.
Die cuts give packaging designers more flexibility. They can hold a product in a specific position, fill a gap in the case, or combine with partitions and pads to create a complete interior system.
Understanding board grades
Corrugated interior packaging is made from single wall or double wall board in a range of strengths. Grades are usually described in ECT or Mullen terms, and it helps to know what each one means:
- ECT (Edge Crush Test) measures edgewise compression strength.
- Mullen measures bursting strength, using a burst test standardized by TAPPI.
Because ECT and Mullen measure different properties, they are not interchangeable stacking-strength ratings. The right choice depends on the product and application, so share those details with your supplier and ask which grade fits.
Paper choice matters too. Kraft is the standard for many applications, but specialty papers and coatings may be available when a product or environment calls for something different.
Corrugated and solid fiber
Interior packaging is also produced in solid fiber, and both materials have a place. Corrugated board’s fluted construction gives it cushioning and rigidity, which is why it is a common choice for protecting breakable or heavier products. Solid fiber is a dense, durable material available in a range of calipers, typically from .018″ (18-point) to .047″ (47-point), in plain chipboard as well as specialty papers and coatings. Some customers specify solid fiber for their applications, and it performs well in many of them.
The best approach is to work with a supplier that produces both. For example, Great American Paper corrugated partitions are available in all strengths of single wall and double wall corrugated, in both ECT and Mullen grades, and the company also produces solid fiber partitions and pads. Having both options under one roof makes it easier to choose the material that suits each product.
A note for box plants
Box plants are often asked to supply interior packaging along with the containers they sell. Offering the complete package can strengthen customer relationships, but it also raises questions about labor and capacity.
Partition production and assembly can be labor-intensive. Working with a dedicated specialist can help box plants evaluate that work separately and manage their production capacity more effectively. When comparing options, look at total delivered cost, capacity, service, and the value delivered to your customers, rather than unit price alone. Sourcing is not automatically the lower-cost option, so it is worth reviewing each program on its own terms.
How to choose an interior packaging supplier
Whether you are a brand owner or a box plant, the right supplier relationship makes interior packaging easier to manage. Questions worth asking include:
- Do you produce partitions, pads, and die cuts, and in both corrugated and solid fiber?
- Which board grades, wall constructions, and papers do you work with?
- Can you review my product dimensions and recommend a configuration?
- Do you handle both small runs and high-volume programs?
- What turnaround is typical for an order like mine?
- How do you maintain order accuracy and consistent product quality, and how are any concerns addressed?
Look for responsive, personalized service as well. Clear communication on quotes, changes, and order status makes a real difference over the life of a packaging program.
Where to start
Great American Paper specializes in corrugated and solid fiber partitions, pads, and die cuts. The company serves customers throughout North America. If you are reviewing your interior packaging or sourcing it for the first time,Great American Paper corrugated partitions are a useful starting point for understanding the board grades, materials, and options available.
The bottom line
The outside of the box gets noticed, but the inside does much of the work. Partitions separate, pads layer and support, and die cuts handle the shapes that do not fit a grid. By matching each component to your product, choosing the right material and grade, and working with a supplier that understands interior packaging, you can build a packaging system that fits your products and your operation.
