Until last year many people who bought or specified corrugated boxes considered it as a relatively simple job. Or so they thought. It was easy to just order a "Rule 41" box, figuring that’s all that’s needed to do the job. Besides, it’s a standard of the industry, really almost a commodity, so it’s cost should be right in line. No matter that technically "Rule 41 boxes" don’t address all of the packager’s shipping and handling needs as long as they usually worked.

Those easy buy days, if they ever really did exist, are over. Things are not so simple now that there are some real choices you must make. There are "high performance" boards, recycled boards, and alternates available in Rule 41 grades. How in the world are you to know which is the right one for you, what will work, what won’t, and what’s the best buy? It’s not easy or simple, but not too complicated either. You can make the right decision without a Ph.D in packaging.

Before we see how, let’s take a look at what has happened to the old world of corrugated that brought about this opportunity to make some significant choices. First, from both a historical and an importance perspective are the carrier regulations on corrugated boxes, Rule 41 for rail and Item 222 for truck. Dating back to the early part of this century, rules were set for certain minimum grades of fiberboard to carry specified maximum weights and sizes. Over the years, the box industry standardized around these minimum grades and so did shippers. If they intended to ship "x" pounds of product, then a "test" grade of box was bought and used based on what was acceptable to rail and trucking carriers.

But keep in mind that rules were minimums and that they were intended to serve only the carriers as a guarantee that their customers (the shippers) had used sufficient boxing material to survive the transportation leg of the distribution chain. The rules did not, nor do they now, address what shippers need for packaging performance in other parts of distribution, particularly storage or warehousing.

Early in 1991, the carrier rules were amended by offering an alternative to the old "test" grades if shippers wished to use something else. The something else is "ECT" fiberboard, that is material measured for its edgewise compressive strength by the Edge Crush Test. It is still a "test" material, but an entirely different determination than the old burst (Mullen) test. Whereas the burst test relates to rough handling durability of fiberboard, ECT is a true performance test, directly correlated to the stacking strength of the box.

Problems have arisen for some who have selected the alternative choice, however, because they continue to use carrier rules as their "standard" and because they incorrectly assume that the two alternatives are equal. Only by analyzing the packaging performance requirements of your distribution system and then testing an alternative can you be assured that a switch will work.

The problem has been compounded by too great an emphasis by some people on the cost saving aspect of ECT-certified boxes over burst-certified. The cost saving arises because ECT board has no minimum basis weight requirement while burst grades still must meet minimum weight. Salespeople sometimes feature this point without noting that the performance may be different. Buyers only see the purchase cost savings and don’t recognize the inequality between the two types of fiberboard.

Here is a case in point. I recently purchased some seedlings and flower bulbs from a nursery in Michigan. The purchase was shipped to me in a 32 ECT certified box which they evidently had failed to test in comparison to performance of a 200 burst grade. The four pounds of seedlings and bulbs arrived by parcel post, but the box had failed miserably, allowing 8 of 10 items to fall out en route. The box was squashed to about half its original depth and two vertical edges were completely torn out (see photo).

Generally, if you are experiencing crushed boxes and stacking problems, consider ECT specification. If it’s containment strength and puncture resistance that is needed, use burst or puncture test specification. Sometimes both requirements are indicated, and if that is the case, then specify both. In the case described above, both types of failure are present, but the rupturing and loss of contents is the most important so burst strength should be specified.

Here is an example of proper consideration of distribution hazards: a product for shipping weighs 52 pounds, measures 19" x 16" x 14", is shipped LTL common carrier, and storage is 8 units high. Referring to carrier rules, a minimum grade of 200 psi burst is required or alternately an ECT of 32 lb/in. Perhaps previous experience or testing has shown that the 200 burst grade will work for the carrier part of distribution, but what about the storage 8 high? There will be 364 pounds resting atop the bottom box in a stack. If you were to do a quick laboratory compression test, the 200 burst grade box will prove much too weak. Lacking a lab test, you could also consult with a packaging professional who knows corrugated and they will confirm the weakness based on experience.

If the actual strength of the contents cannot make up the difference in stacking strength needed, then a heavier grade of fiberboard is required. How much heavier can be calculated, and then verified in a lab test or actual warehouse stacking. For this example, an ECT specification of 66 lb/in should work based on calculations from the well known McKee formula postulated in 1963:

There should be little question of its rough handling capability since the weight of fiberboard for 66 ECT will be at least double that used in a 200 burst grade.

Where do the so-called "high performance" boards fit in? They have been developing over the past 10 years or so in response to both customer needs and changes in sources of supply. New paper-making processes and shorter fibers in raw materials (wood pulp and recycled boxboard) provide fiberboard with higher ring crush and subsequently higher ECT per pound of board. To capitalize on this feature the box and paper industries convinced the carrier regulation committees to provide an alternative to burst grades in their rules and this was done in 1991 as previously mentioned.

The key advantage to producers in obtaining the alternate choice was the elimination of any minimum basis weight of paper for ECT grades. Now it competes against burst grades with an advantage of no weight requirement while burst is still tied to weight minimums. Also, buyers/users of corrugated boxes must be continually aware that there is not a correlation between good burst in a given grade and a high ECT or visa versa.

Therein lies one of the reasons for confusion. Carrier-grade boxes are being sold often as high performance ECT when in fact they may indeed be lower performance. They may be lower for a couple of reasons. For one, the ECT values in Rule 41/Item 222 were set very low so that almost all boxes produced at the time would be acceptable. Another reason for lower performance may be due to lower burst strengths inherent in lower weight "high performance" board. For instance a packager may have been buying 200 burst grade certified boxes that happened to also have a minimum ECT of 40. In making the switch to a legally alternate 32 ECT grade, however, the new grade may also have a 15% lower board weight and 20% lower burst strength. Legal according to carrier rules, but will they work in the total distribution cycle? For some they will, for others they will not. The only way to find out is to test them before making the final switch.

For the unsophisticated shipper who does not have a testing lab available, tests may take the form of actual "test shipments" where the results are carefully monitored. The major drawback for this method of testing is the number of shipments required to be statistically assured that most variables in distribution hazards have been encountered. Time is long and transportation costs high.

In a laboratory, one can utilize ASTM or NSTA performance test procedures to arrive at answers in less than a day. Interestingly, NSTA has taken the position that packages certified for their seal must be retested if a packager switches from burst to ECT certified corrugated shipping containers.

While many packagers are taking advantage of the cost saving basis weight reductions of high performance boards and enjoying good results in shipping, others have found that they still need the rough handling containment and puncture resistance provided by burst graded boards. This is particularly evident in small parcel modes of shipment (PP, UPS, FedEx, etc.) but also to some extent in the unpredictable LTL trucking environment.

What will those shippers do if the often predicted phase-out of burst graded boards really happens? And, listening to the box industry spokesmen, its easy to see why it could happen. Most of the major producers, particularly those with integrated paper mills making high performance containerboard, talk only about compression strength of boxes and related ECT of the fiberboard. They sound as though rough handling has ceased to exist and hardly ever do punctures occur. I disagree with this approach and suggest that rather than talking in a disparaging manner about burst/puncture boards, the fiber box industry should change the misleading name of "high" performance to a more specific term like "high stacking" or "high compression" performance.

One way to assure that the source of supply for burst graded board doesn’t dry up is for packagers to insist on that specification if they really need it. Producers will respond to marketing demand and if there is enough of it for burst grades, there is no question that at least some of the more popular ones like 200 test will survive. For specifications, buyers of corrugated boxes can find help in several places rather than depending on Rule 41/ Item 222.

The latest edition (1992) of the Fibre Box Handbook by the Fibre Box Association contains new sections entitled "Structural Design" and "Specifications". These can be used by buyers as an aid in developing a set of box specifications based on their own particular needs, but identification of these needs and their translation into box and fiberboard specification requires expertise and experience. If the buyer does not have a qualified person with this background to develop the specs, box manufacturers are ready to step in and help. While this may be expedient, packagers should be aware that sellers of boxes, like sellers of any product, may arrive at a set of specifications that are written around their product to the exclusion of the competition. Perfectly legal but buyer beware.

Another source of specification assistance is being developed by ASTM. The third draft of a Standard Practice for the Selection of Corrugated Fiberboard Materials and Box Consturction based on Performance Requirements is being considered for balloting by the D10 Packaging Committee of ASTM (update- approved in 1994 as D5639). While previous drafts of the proposed standard have been opposed by box manufacturers, the latest version contains significant changes which appear to have the producers support. The standard will cover the major attributes of corrugated, list test methods and suggested tables for them, and a lengthy tutorial leading users to final specifications. It is designed to make it possible for buyers/users to develop specs without outside help.

The drive in distribution packaging has been toward performance based specifications for the past 23 years, starting with the SPHE sponsored Industry Packaging Review Committee 1969-1976. Although that effort largely failed to meet its original goals, the seed was planted and we are now seeing some of the results. It is up to buyers/users of corrugated boxes to harvest the benefits by starting now to set their specifications based on their own distribution performance requirements. Reduced damages and lower packaging costs are guaranteed results.