Reader Mailbag: Chainalytics Packaging Engineers Answer Your Questions!
We came across your previous blog article and hoped that you might be able to help us out with a data question. Our product is shipped in a double-wall, corrugated box for the secondary protective packaging. We’ve seen a hundred versions of the following table comparing the bursting test and edge crush test standards:
We’re familiar with the two types of testing, and we’re sure that the table is accurate. What we can’t seem to find is the data behind the table, or even a national regulation or standard that supports it. Can you help explain?
Dan, great question! We established some basics on this a few years ago when we explained the difference between Mullen grade (burst) and ECT board in this blog entry. We did some additional digging in attempt to tackle Dan’s question head on, and find that data source he was searching for. However, all references we identified only had the comparative table noted as an approximation.
The paper combinations for both board types are driven by the paper weights available from the corrugator’s own mills or through purchasing from a third party. Most corrugators utilize their own special blend of paper combinations to meet ECT requirements, and can vary by region or even by plant. This allows the corrugators flexibility to use a wide variety of paper combinations to achieve the minimum ECT requirements, while minimizing costs.
Mullen grade board however requires a more exact combination of papers with one or two heavier weight liners to meet the burst strength requirements.
In general, ECT and Burst are not an apples to apples to comparison, and are not intended to be. Both utilize different grades of paper and different combinations for their own unique purposes. There is a reason ECT boards are less expensive, because there is less paper there. So in a true static compression test, this table reflects their approximated equivalents based on compression, but that may not reflect your package’s performance in your supply chain.
The one steadfast answer to get to the bottom of it all is to test your boxes and determine their burst and ECT characteristics as well as simulated lab distribution testing. Mullen board can often have similar or better performance that it’s comparative ECT counterpart, but the only way to truly know is to test it!
Thanks for your question!