Do Board Grade and Flute Size Affect Pin Adhesion

August 2, 2017

Desi asks,

Do box grade and flute size have an effect on the Pin Adhesion Test? Also, I know that the double backer bond is stronger than the single facer so how do we know which side failed first in the normal pin adhesion test since no side is being held firmly to the base?

There is some thought that at the lower grammages and lower caliper the liner is not “rigid” enough to support itself or lay flat enough for the pins to do an adequate job of breaking the glue line. I have seen pin targets as low as 42 for 23# C flute.

The Pin Adhesion test is selective separation. The weakest point will be the first to give. In this test one side is supported while the other is tested, therefore sides should are tested separately. Using the TAPPI method, it should not be possible to test both sides in the same test.

If you search “pin adhesion” on this site you may find more helpful information.

— Ralph


GMI Certification for Corrugated Converters

June 15, 2017

John asks,

We recently had a customer ask if we were GMI certified. What do you know about this, how long does it take to receive the certification and do you know any Independents that have GMI certification?

Our associate Scott Miller at BCM Inks helped us with some background and industry knowledge on the subject.

The GMI certification awarded by Graphic Measures International (gmi), a St. Louis Missouri based company that certifies, monitors and measures the performance of packaging suppliers with a main focus on positioning plants to meet graphic standards of quality and color. Global brand owners often require this as a measure to help them maintain a consistent appearance of their brand.  Through training, process development, certification and continual monitoring GMI ensures plants are maintaining and running to industry standards.

The GMI certification process is rather in-depth and can take 3 to 5 weeks. The process measures everything from light booths to actual print samples. Many brand owners who are quality and color critical will only qualify or use printers who are GMI certified. This gives the brand owners the confidence that the printer has process control in place to provide repeatable results that will meet their global standards.

According to Scott he can name any [particular] corrugated printer who is GMI certified. “However, I see their certification stamp on a lot of light booths when I’m in plants.”


— Ralph

What is the difference between ECT and ECV?

June 9, 2017

Charles asks,

What is the difference between ECT and ECV?

ECT (Edge Crush Test) is the testing method. ECV (Edge Crush Value) is the actual outcome or reported result of the Edge Crush Test. ECT is a measured in pounds per lineal inch of load bearing edge. Though it may sometimes be reported as ECV or lb/in it is typically reported or listed as an ECT value such as 23 ECT.

ETC has widely replaced the use of the Mullen test as ECT is considered by most as a more accurate test of the stacking strength of a corrugated box. It measures the edgewise compressive strength of a corrugated sample on an axis parallel to the sheet. Mullen, on the other hand, measures the bursting strength of the face of the corrugated sample, or on an axis perpendicular to the sheet.

– Ralph


Moisture Test Comparison MRA vs. non-MRA Box

May 24, 2017

Steve asks,

Would you have or could you please direct me towards any testing data/statistics on a box with MRA vs. a non-MRA box?  I would like to see what kind of improvement it shows in a moisture-related test.

The dimensions, flutes and composition range (very small to large boxes; B/C, E/B, and B flutes; 32ECT to 71ECT), and I don’t have much info on supply chain.  A customer just looking for any testing data that he can get on MRA to demonstrate that it does improve performance in moisture.

For assistance with answering this question I reached out to Clayton Clancy at Kruger. He has provided this this detailed study on stacking performance when using water-resistant adhesives, complied by the Institute of Paper Chemistry, which high-lights paperboard performance improvements when using WRA additives. He cautions that there are varying terminologies used when discussing water resistance such as (MRA, WRA and WPA), with that in mind I hope this will be helpful.

— Ralph