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Collaborative Testing Services, Inc.   anniversary

P.O. Box 650820, Sterling, VA, USA 20165-0820  1-571-434-1925


Quality containerboard packaging is certainly a numbers intensive journey. Corrugated containers are only as good as the quality of their component parts. Knowing that your components meet, if not exceed, quality specifications is critical to the success of your laboratory.  Both producers and consumers depend on the data that your laboratory generates: week-to-week and month-to-month, your results are the engine of the industry. You need an interlaboratory testing program that will provide you with an unbiased way to determine whether you are indeed achieving your measurements goals.
Unique among the CTS programs, the Containerboard Program was designed as a collaborative reference program: linerboard, corrugating medium and corrugated board samples are taken from one lot, randomized, and sealed at one time for repeated distribution. Corrugated boxes are selected and randomized in a similar manner. Weekly and monthly testing of these materials provides a means of continuous measurement assessment that allows your laboratory to monitor performance and take corrective action if necessary. Helping you keep your numbers on track is why the industry is on board with CTS' Containerboard Program.


Bursting strength, ring crush strength and short-span compression (STFI) are offered in the Weekly Program with 42lb. linerboard tested each week and with 35lb. & 52lb. linerboard tested weekly in alternating months.


Flat crush strength (Concora), corrugated fluted crush strength, ring crush strength and short-span compression (STFI) are offered as part of the Weekly Program with 26lb. medium tested each week.

Corrugated Boxes

Box compression strength (BCT) is offered on corrugated boxes as part of the Monthly Program with un-erected boxes setup and tested each month for top-to-bottom compression resistance. At this time samples can be shipped only to addresses in the US, Canada and Mexico.

Corrugated Fiberboard

Edgewise compression strength is offered on combined board as part of the Monthly Program with 5" x 7" ECT blanks tested each month in accordance with TAPPI Method T811 (wax dip method) and/or TAPPI Method T839 (clamp method).


Roughness using the Stylus method, Roughness using the Sheffield method, Gurley air resistance, coefficient of friction (slide angle) and internal bond strength are offered in the Monthly Program with linerboard tested each month.


Alternate samples for automated testing systems. 24 x 12" 42lb linerboard samples are provided for weekly testing of Bursting strength and Short-span compression (STFI) along with the corresponding 35lb. & 52lb. linerboard in alternating months. Data for Roughness using the Stylus method, Roughness using the Sheffield method, & Gurley air resistance can also be reported.

CTS Containerboard Program History

Outside of the industry, nobody thinks about corrugated boxes that is, nobody does until a new LCD TV is damaged by a structural failure of its box or a product sits on the shelf because it is surrounded by more attractively packaged competitors. Boxes: an everyday item that must perform to incredibly tight tolerances to be effective. The containerboard industry has worked to address such quality and performance issues through standards and testing. For half a century, the Containerboard Interlaboratory Program has been involved in this industry-wide effort.

The roots of the modern Containerboard Interlaboratory Program are directly traced to the Collaborative Reference Program (CRP) for Linerboard first conducted in October 1969. The first formal, nationwide program was administered by the National Bureau of Standards (NBS, now the National Institute of Standards and Technology, or NIST). The joint government industry program was sponsored by the Fourdrinier Kraft Board Institute (FKI) with the cooperation of the Technical Association of the Pulp and Paper Industry (TAPPI). This initial work focused solely on Bursting Strength testing on kraft linerboard work that has continued uninterrupted in the interceding years. (For the curious, a Burst Strength of 117psi was the first collaborative mean on the 42lb. linerboard in October 1969.) A companion program for corrugating medium flat crush strength was initiated by the same groups (NBS, FKI and TAPPI) in May 1973. The two separate programs were united after 3 years.

The program and the involved organizations evolved continuously as the industrys needs changed. Although the personnel operating the program had not changed, by June 1976 CTS was formally operating the Containerboard program. FKI became FKBG and then CKPG (the Fourdrinier Kraft Board Group and the Containerboard and Kraft Paper Group, respectively, of the American Paper Institute, or API). Ring Crush testing on linerboard was originally initiated in CTS separate Paper & Paperboard Program in 1975. After the Ring Crush test was moved to the long-standing Containerboard CRP in 1983, another major addition to the program followed quickly: in July 1984, Short Span Compression (STFI) was added for both linerboard and medium. 

As stated above (and unique among the CTS programs), the Containerboard Program was designed as a collaborative reference program: linerboard and corrugating medium are taken from one lot, randomized, and sealed at one time for repeated distribution. Even from the first study in 1969, the CRP has been designed to provide laboratories with weekly testing samples. But within the industry there was a demand for adding materials that were impractical to supply on a weekly basis or for properties that did not require weekly monitoring. These materials, including corrugated board and boxes, and properties, such as coefficient of friction and porosity, were originally added to the Paper and Paperboard Program, like Ring Crush was years earlier. And, similar to the events of 1983, the movement of Edge Crush Testing (ECT) into the Containerboard Program spurred a period of evolution in the program. Between 2000 and 2004 ECT, Box Compression, Stylus Smoothness, Coefficient of Friction Porosity and Internal Bond Strength were added. In 2006, these tests were grouped into the Monthly Program run concurrently with the traditional Weekly Program. Also during this time, Corrugated Fluted crush (CFC) was added as a weekly test. 

Over time industry sponsorship turned to affiliation, with industry providing technical guidance instead of monetary support. Many different industry groups have provided technical input through the years, including the aforementioned FKI, FKBG, CKPG, and TAPPI (through the Containerboard Division and the FISCOTEC committee), as well as the Fiber Box Association (FBA) and the Association of Independent Corrugated Converters (AICC). The cooperative effort continues with the Containerboard Program providing feedback to industry standards writing groups on the effectiveness of their standards in real laboratories.


CTS Containerboard Program Schedule

Enroll at any time during the year. A subscription to a test includes 12 cycles, which are outlined below. Containerboard tests are divided into two groups weekly and monthly. Regardless of whether a test is performed weekly or once per month, all samples ship at the same time. Weekly tests include primary linerboard analyses and primary corrugating medium analyses. Monthly tests include corrugated box compression analysis, corrugated box edge crush analysis, and additional linerboard analyses. Refer to specific test descriptions for complete test information.

Important exception to note: Participants in Test 201 (Corrugated Box Compression Test) receive samples for twelve months worth of testing in one shipment and perform testing monthly. Partial year enrollment is available and will start with the next scheduled shipping date. The shipment will consist of a full year's sample materials and the ability to report data for the remaining months of the year.

Results must be submitted on or before a data due date in order to be included in the report. Participants can track shipments, submit data and access reports through the CTS Customer Portal.

Enroll Between: Samples Ship: Testing Conducted: Data Due: Monthly Letter Code:
January 2 - February 1 2nd Week of March April 1st Monday in May D
February 2 - March 1 2nd Week of April May 1st Monday in June E
March 2 - April 1 2nd Week of May June 1st Monday in July F
April 2 - May 1 2nd Week of June July 1st Monday in August H
May 2 - June 1 2nd Week of July August 1st Monday in September J
June 2 - July 1 2nd Week of August September 1st Monday in October K
July 2 - August 1 2nd Week of September October 1st Monday in November L
August 2 - September 2nd Week of October November 1st Monday in December M
September 2 - October 1 2nd Week of November December 1st Monday in January N
October 2 - November 1 2nd Week of December January 1st Monday in February A
November 2 - December 1 2nd Week of January February 1st Monday in March B
December 2 - January 1 2nd Week of February March 1st Monday in April C

Summary Reports

Portal Links

Participants in CTS Containerboard Program tests can access Test Instructions on the CTS Customer Portal.

A Guide to Interpreting Performance Analysis Reports, available as well on the CTS Customer Portal, assists participants in understanding and getting maximum benefit from the individual reports issued at the completion of each testing round.