Providing worldwide interlaboratory testing since 1971

New to the Containerboard Program?

If your laboratory is planning to subscribe to the Containerboard Interlaboratory Testing Program, you may have questions about how the program works. This "how-to" guide for containerboard laboratories is designed to answer many of those questions.

How it Works

Testing samples are manufactured from one source and distributed to participants for concurrent testing. The laboratories test the samples and return the results to CTS on or before a data due date. CTS will analyze the data and compile the information into a report that is distributed to the participants.

Getting Started

The Containerboard Program is divided into a Weekly Program that provides 48 tests per year and a Monthly Program that provides 12 tests per year. Laboratories can enroll at any time; your subscription will start with the next scheduled shipping date and will include a subscription for a full year of testing. The Containerboard Program Schedule illustrates the test distribution and other pertinent program information.

Our Materials

The Containerboard Program materials originate from genuine mill production. CTS obtains a roll of linerboard of consistent stock. The roll is slit down to 12 inch portions. CTS randomizes the sheets to distribute the variation evenly among the sample packs. The samples are pre-conditioned and packaged in moisture proof mil-spec barrier bags.

Corrugated board for ECT and corrugated boxes for BCT are manufactured specifically for the program. The corrugated board and box are derived from consecutive corrugator sheets with no changes in linerboard rolls during the run. The ECT samples are then manufactured from the board on a cutting table. The ECT blanks are randomized, pre-conditioned and sealed in a moisture-proof mil-spec barrier bag. The corrugated boxes for compression testing are also randomized by CTS and subdivided into laboratory lots that will last for the entire testing year. Corrugated box samples are not pre-conditioned by CTS.

It is important to note the materials that are used for each test. Please click here to see the Material Chart that lists what materials are used in Containerboard Program tests.

Your Samples

The sample package you receive contains test samples and data reporting sheets on which testing results are returned to CTS. The Containerboard Specific Testing Instructions are conveniently located on the CTS Portal. Test instructions contain amendments and additions to the test methods. The Containerboard Interlaboratory Testing Program adheres to the TAPPI test method for each property and also for sample conditioning and preconditioning procedures.

Submitting Your Results

Test results can be submitted to CTS through our convenient Online Portal, mail, or fax. The CTS Portal offers a secure and dependable method for your laboratory to electronically submit testing results directly to CTS. All testing results must be submitted to CTS by midnight of the data due date for inclusion in the report. The data due date is typically the first Monday following the testing month.


Our data analysis includes calculation of the individual laboratory means for each week of the month, each laboratory’s statistical data for the month (mean, within-lab standard deviation and standard deviation between weeks), and each laboratory’s cumulative data for up to 16 weeks. Laboratory results for the week, month and cumulative periods are compared with consensus values for all included laboratories allowing participants to evaluate agreement, consistency and constancy against the industry. The Sample Individual Report and Guide to Individual Reports show laboratories the statistics used in the reports.

Performance Analysis Report

Following completion of the data analysis, CTS prepares and sends an Individual Performance Report by e-mail to a Primary Contact designated by you. In addition, CTS uploads your report to the Online Portal where the Primary Contact may access it at any time. Everything within each report is tailored specifically to your lab, including the data and charts.

Web Summary Report

CTS will publish a Web Summary Report that allows laboratories to view the results for all participants in each test. CTS will randomly generate for each laboratory a temporary "WebCode" to protect the confidentiality of results displayed in the summary report. The WebCode is unique to each laboratory and is not permanently associated with a specific laboratory. Web Summary Reports from prior cycles can be found on the Containerboard Summary Report page.

Quality Manager Report

For those companies that have multiple locations and several laboratories participating in the CTS Containerboard Program, CTS creates a Quality Manager Report. This customized report is prepared for the Quality Manager and designed to allow for the easy comparison of multiple laboratory's results in a single report. Please contact the Containerboard Program Manager via e-mail for more information about our Quality Manager Report.

Still have questions?

We would like to hear from you.  Call us at 571-434-1925 or e-mail

Updated: 24 July 2017

Copyright © CTS, Inc., 2018

Collaborative Testing Services, Inc.
P.O. Box 650820, Sterling, Virginia, USA 20165-0820
Phone: 1-571-434-1925