Insulating Properties of Corrugated

August 15, 2019

Rich asks,

I have a question about the insulating properties of corrugated and the impact of vent holes in dairy applications. I have a dairy customer who is looking to pack sour cream in cartons. It is filled at 100 degrees F and put into 35 degree refrigeration. What is the difference in how long it will take to get down to 40 degrees if there are no vent or hand holes in an RSC against if there are some? Is there a formula that exists for the cooling time? This would be an ECT48 DW RSC. Thank you as always for your guidance.

Here is a link to a research paper (Overall Effective Thermal Resistance of Corrugated Fiberboard Containers) complied by the US Dept. of Agriculture and the Forest Products Laboratory. Pages 4 – 6 of this report contain information regarding the affect of vent holes.

The location and area of the vent holes as well as the velocity of the circulating air will also have an affect on the thermal transition time.

Would it be possible to perform an experiment using a grill or meat type thermometer to determine when the core of a loaded box with vents and a loaded box without vents reached the desired 40 degrees F?

— Ralph

Tests for Quality of Board

August 14, 2019

Harendra asks,

We are in the process of evaluating the quality of OCC grade 11 & 12. Can you suggest what specific test should be performed for quality evaluation of these two grades for production of container boardpaper?

I would suggest contacting Bill Moore at Moore Associates in Atlanta. He is an expert in this area.

Moore & Associates
Phone: (770) 518-1890

— Ralph

Convert European Board Specs to ECT

August 14, 2019

Jeff asks,

We have a customer that is based in Germany and is opening a branch in Tennessee.

They gave us some specs with the below board grades:

2.91BCB (alternative 2.91 AC)





We need to convert them to ECT values.

Do you have any information on how I can convert them?


Jeff, usually the metric equivalent to our pounds force per linear inch is expressed in kN/m but in this case I believe we are looking at kg-f/in so you need to divide their requirement by 0.038 to obtain the equivalent Imperial value. We have compiled a list of conversions that you may find helpful. (English Metric board conversions)

Conversions for grades listed above would be,

2.91BCB (alternative 2.91 AC)   — 76 ECT BCB Triplewall or AC Doublewall

2.70BC — 71 ECT BC Doublewall

2.91ACA — 76 ECT ACA Triplewall

2.30BC — 61 ECT BC Doulbewall

1.40C — 37 ECT C Singlewall

— Ralph

Measuring Force to Break PDQ Perforation

April 10, 2019

Pete asks,

We have been working with several different perf styles to provide ease of opening for retail ready PDQ style trays. There is a variety of different sizes and the majority of the items are earmarked for Walmart stores. While our execution has been successful we do not have an effective process to measure the force required to open the boxes to ensure consistency. Are there any tests to can recommend or any laboratories capable of testing the variables we are trying to measure?

Very good question Pete! You might review TAPPI T-813 which discusses the tensile test for the manufacturer’s joint. There are also jigs for compression testers that will measure the force necessary to bend a crease through a certain distance, usually to a 90 degree angle.  Also check TAPPI 577 and 829 for ideas.

Another option may be to use a burst test at the point of the perf. TAPPI T-810 describes the burst testing method. The question would be whether conventional equipment would have a satisfactory range of operation/measure or would the bursting strength of the perforation be below the recommended operating range of the equipment.

Now let’s toss this one out to our readers to see what their thoughts and experience may be. Has anyone done this type of testing, or is anyone aware of a specific method for testing the force necessary to break a perf?

– Ralph