Packaging Supplies: Part 1 - Exterior Packaging Selection

William R. Armstrong, CPP
Technical Development Manager
Sealed Air Corporation

The following is Part One of a two part series of articles covering Packaging Supplies. This installment deals with exterior or shipping packaging forms and the second article with interior packaging (primarily cushioning and void fill). In both installments, the processes by which materials and options are selected will be addressed along with an overview of the anticipated performance characteristics for broad categories of these supplies.

Even though these articles are geared toward small-to-medium sized operations (between 1,000 and 5,000 packages per month), those falling slightly above or below this range also can benefit from this discussion.

Exterior Containers - The Start of the Selection Process

Certainly the first, if not the most important decision that has to be made in the process of choosing the right package for a product is deciding which kind of shipping container should be used. Although we tend to think automatically of shipping containers in terms of corrugated boxes, many products can be safely and economically shipped in any of a number of different types of mailers. Each type of container (boxes and mailers) has its own set of advantages and limitations. An efficient shipping operation is one in which each product shipped will be sent in the type of container most appropriate to the product’s requirements.

The first determination should be either a box or a mailer. Such determination should be based on the specific attributes of the container and requirements of the products to be packaged. First, we should look at the various features of each type of container.

Corrugated Boxes

Boxes made with various grades and types of corrugated fiberboard are the most commonly used shipping packages. These boxes offer structural strength and rigidity for stacking and compression loads, secure closure (for product containment and security), an extremely large range of sizes capable of containing any product or groups of products from the very small to the very large, and are available locally nearly anywhere in the world. For the protection they afford, corrugated boxes can be considered to be lightweight (compared to wooden crates, barrels, etc.) and reasonably inexpensive.

Boxes are classified by their style and the type of corrugated fiberboard used in their construction. The "Fibre Box Handbook" published by the Fibre Box Association (for more information, a Packaging Container Resources listing appears at the end of this article) describes dozens of standard box styles available in the U.S. today. Note that FEFCO in Europe publishes a comparable listing of styles in common use in Europe. Each box style is designed for a combination of physical and performance attributes of the finished container while minimizing or optimizing the amount of fiberboard required. The most common style in use in the U.S. is the 0201 - Regular Slotted Container (RSC) in which all flaps are equal in height and the major flaps (the longest pairs) meet in the middle. This style uses the least amount of fiberboard for any given box dimensions.

In addition to styles, boxes are categorized by the grade of the fiberboard used. Two common means of classifying board is the Mullen Burst Test and the Edge Crush Test (ECT). Commercial boxes will most often have a Box Makers Certificate (BMC) stamped on the bottom flaps. Typically, the stamp will be circular with information included inside. Specifically, the grade of board used (Burst or ECT) will be listed along with size and gross weight limits for that style of box and that grade of corrugated. These limits were originally established by the railroads for common commodities shipped by rail. They have been carried forward by the motor freight industry, primarily those involved in LTL Common Carrier shipments.

It is important to consider however, that the size and gross weight limits are originally based on requirements for boxes shipped on pallets, used primarily for their stacking strength. Such limits will seldom apply to packages shipped LTL common carrier, UPS, Federal Express, Postal Service, etc. Recent studies indicate that these limits are too high for these types of shipments. In fact, for valuable or critical products shipped single parcel or LTL, it is realistic to consider limiting the amount of product in a box to 50 percent or 60 percent of the BMC’s stated maximum gross weight. The shipper might have to go up one or two categories of Mullen Burst or ECT value, but the trade off of cost versus potential loss of product might be more than worthwhile in these cases.

Shippers and Mailers

These types of bags or envelopes are designed for shipping products via single parcel systems i.e., UPS, Postal Service and Federal Express. When their use is appropriate, they offer the shipper greater economies and efficiencies than corrugated boxes. Mailers are simple to pack and to close. They use minimal materials, are lighter weight, take up less storage space and are more economical to purchase than boxes. However, they cannot be used for every possible shipment.

The following criteria may help establish whether a shipment can go in a mailer or whether it would be more appropriate to use a corrugated box:

1. The dimensions of the products to be packaged must be within certain limits. Height should not exceed 2 inches or 3 inches - generally the product should be relatively flat. And, the length and width of the product must both be such that they will fit into an available mailer size. Mailers come in several standard sizes. Products having dimensions greater than these standard sizes will most often then have to be packaged in some other manner. Corrugated containers are often available in special sizes for short runs to accommodate odd sized or configured products.
2. The products to be packaged should be capable of withstanding compressive forces. Packages will be stacked inside carrier vehicles with other packaged products on top during shipment. The weight of these will bear on all items in the stack below. For products that can be damaged by compression (cigars, for example), a corrugated container would be necessary. Otherwise, if the product can withstand compressive loads on its own, then mailers can be a preferred alternative to boxes.
3. Although there are several types of padded or cushioned mailers, including air cellular, foam lined and macerated paper, a product shipped in even these should be fairly rugged. A crude way to estimate whether a product is sufficiently rugged would be to think about whether dropping it from mid-thigh height, maybe 24 inches high, would cause substantial damage. If it would, then the shipper would be advised to think about using corrugated containers with an inch or two of cushioning materials. If the product would probably survive such an impact, a cushioned mailer might provide enough protection. The choice between air cellular, foams or macerated paper will be based on weight of the mailer - air cellular is the lightest, paper the heaviest - or other factors such as surface protection and water resistance.

For products which seem appropriate for shipping in mailers, the user must then decide which type is most appropriate. They are available in several different styles including utility (paper or plastic), reinforced (no padding, but having greater resistance to tear and puncture), cushioned or padded (as mentioned above, air cellular or foam lined, macerated paper, etc.), and rigid (rigid fiberboard construction prevents bending and creasing of the contents). Each type can be purchased with or without self-sealing capabilities and are available in a wide range of standard sizes (widths and lengths). Selecting the right size mailer for a given product can, at times be a challenge. A "Guide to Choosing the Correct Size Jiffy® Mailer from Sealed Air" is on Sealed Air’s Web site www.sealedair.com. There you will find a calculator for determining the correct mailer size for your product.

Summary

We have concentrated in this article on factors to consider when selecting a shipping container - either boxes or mailers. The first objective is to determine whether a box is necessary for the products being shipped rather than being able simply to place them in mailers.

Once this determination is made, the next challenge is to select the right box or mailer. For boxes, this is typically the selection of the right dimensions (contents must obviously fit into the box) and then being sure that the corrugated used is sufficiently strong to both protect the products during shipment and to maintain package integrity through all the impacts, compressive forces, vibrations, heat, moisture and humidity the package will encounter during shipment.

For mailers, the selection of the appropriate type will depend on the nature of the product being packaged, cushioning requirements and susceptibility to folding and creasing. After selecting the appropriate type of mailer, the dimensional requirements will then be based on which size will contain the products adequately.

Proper closure is an issue for both boxes and mailers. For boxes, this most often relates to the selection of specific tapes having the required performance properties for the application at hand. Tapes for box closure are available in plain and reinforced paper and plastic forms, with pressure sensitive or water-activated adhesive systems. The tape chosen for any given range of applications must be strong enough to hold the contents in place and maintain package integrity for the entire shipping cycle. This relates to the strength of the substrate, paper, plastic or reinforced, the type of adhesive system and the width of the tape. Heavy or large boxes will require wider, stronger tapes.

For mailers, we want to make sure that they do not come open in transit. This is most often accomplished using self-sealing designs or pressure sensitive tape. Some mailers may be folded over and stapled, but tape is the more typical option. And, where moisture- or water resistance is an issue, many plastic or plastic-lined mailers can be heat-sealed to insure additional package integrity.

An increasing concern in today’s environment is the incorporation of some type of security or tamper indicative or resistant mechanisms for closures for both mailers and boxes. Additional information on these issues can be gained from visiting the appropriate supplier Web sites.

For those instances where the product must be shipped in corrugated shipping containers, more often than not, the shipper also will have to consider the selection of appropriate interior packaging to be used in conjunction with the container. Generally grouped as cushioning, void fill or a combination of the two, the materials and forms available for these applications are quite numerous. The next segment of this article will deal with the selection and application of these materials.