Archive for the ‘Testing and Specifications’ Category

Corrugated Performance In Sub-Zero Temps

January 28, 2020

Jeff asks,

I have a client who is asking for specific information about corrugated performance at low temperatures (-20 degrees Celsius) for extended periods of time (up to 6 months).  I have not been given specific information about the contents of the boxes, but I suspect it to be clinical trial materials or something similar.  I expect them to be looking for some sort of performance guarantee.  Current board grade is 32 ECT C Flute.  Outside liner would be virgin paper.  The remainder of the box (medium and inside liner) is recycled paper.

Anything you can provide to help me with this?  Or can you direct me to the right place?  Thanks in advance for any help you can offer.

There just is not much out there. Here is a Link to the last industry wide study on freezer storage which is over 70 years old, but still relevant. Note the added box strengths in the chart. Also here is a link to the most recent report from the PMMI on the storage of Corrugated Packaging.

As you stated, the contents of the box is critical and also is the introduction of any moist air from repeated open and closing of the storage unit. Use of aqueous or UV coatings will certainly provide extended resistance to moisture on the boxes’ surface. However, what generally happens is the glue line is attacked by changes in atmospheric conditions. This is where we often see failure under these conditions.

Does any of our other followers have any knowledge or experiences they can care to share on this subject? How about adhesives and sub-zero temperatures? How does temperature affect the difference adhesives we use in the corrugated industry?

— Ralph

Can ECT board be used for UN tested cartons

October 28, 2019

Randy asks,

I asked this question a number of years ago but I was wondering if ECT Board can be used for UN Tested cartons or is Mullen tested board still the only thing that can be used?

That’s probably a yes and no answer. ECT is allowed as long as the packaging can pass an ISTA testing protocol and the liner weights do not vary by more than 5%. A wider 10% range has been approved and included in the most recent version of the 49CFR.

Don’t forget about the maximum Cobb test.

—Ralph

Is Burst and Puncture Testing Performed on Triplewall?

August 30, 2019

Bobs asks,

Is burst testing and puncture testing done on triple-wall boards? I’m having trouble interpreting the minimum fiberboard requirements issued by NMFC Item 22 and UFC Rule 41. Specifically 1100 triple-wall, does the 1100 represent minimum burst strength of 1100 lbs. per square inch? Or does 1100 represent a puncture test value?

That’s a really good question. It is Mullen burst and not a Beach puncture. It is really based on the additive Mullen values of the liners. So if you were experimenting with low Mullen yet high SCT liner and strong mediums, it would be better to go to an ECT standard.

— Ralph

UPDATE

Miranda comments,

TAPPI T810 Section 1.2 states mullen burst is not applicable to triplewall board. If the test is being performed on triplewall it would not be clear what the results would mean.

Pin Adhesion Test (PAT)

August 30, 2019

Sam asks,

Do you have any formal reference of what the ideal pin adhesion test result should be.   For agro boxes (vegetables) we currently use values of 55 to 60  (pound/inch) and in industrial 40 and higher.

We have a particular customer that has experienced some delamination failures. The PAT test value is 27 (pound/inch) which we believe to be too low. However, we are lacking established information to back up our opinion.

I could not agree with you more.  I prefer a minimum, not average, of 45 for industrial application.  My technical associates at TAPPI like this 45 value while I would rather have 55 on all corrugated bonds.  It is most important to know where the failure is occurring: linerboard, medium, or in the starch itself.  Under ideal conditions we want 100% liner failure. As you can see in these photos a very low PAT value can have disastrous results. There is very little liner pull and very little glue with a poor bond.

A good reference for the PAT is the most recent version of TAPPI document TM 821 (TM 821-0M 17 at this writing), Pin adhesion of corrugated board by selective separation.

— Ralph

Pin Adhesion Test sample Pin Adhesion Test sample Pin Adhesion Test sample