August 29, 2025
Previously, I have reported on other technical trade associations through which a significant portion of my knowledge has been obtained over many years. Of course, this does not come directly from the associations but, for almost 50 years, from the people who have been willing to share their expertise for the betterment of the industry. For your sake, we continue to exchange this wisdom with some of the best minds in the industry. At the time of this writing, I was participating in the summer meeting of the Corrugated Board Technical Committee (CORBOTEC) of the Technical Association of the Pulp and Paper Industry (TAPPI).
Besides Ask Ralph, there are additional resources such as TAPPI Connect and the Institute of Packaging Professionals (IoPP), IoPP’s PackChat service, and the International Association of Diecutting and Diemaking (IADD). Speaking of IADD, it just completed its yearly Odyssey Expo. Rick Putch from National Steel Rule and Steve Rote from Metsä Serla delivered a two-day seminar on troubleshooting in the die making and die cutting processes. Feedback indicated it was the best teaching ever.
Back to CORBOTEC. Besides the best networking, this year’s meeting offered presentations on anilox rolls, printing plates, cutting dies, ink metering systems, and press characterization. We focused on image reproductions but left out digital. It’s not all containerboard and corrugators.
Combined Board Moisture Content – An Ask Ralph Question
So, in the spirit of knowledge-sharing, let’s take a look at a recent question I received through Ask Ralph:
“I’m wondering if you could provide some guidance regarding where we should target our moisture content of combined board. We’re running C-flute 31-23-31 100% recycled board. Paper is coming in at 7.6% average.
“We’re using a Denver moisture analyzer. We cut circles of combined board, place into the fixture, and it determines the moisture in the board and provides it as a percentage. We have just started testing combined board off the stacker. We are not testing paper because we receive COAs (certificates of analysis) from our mill noting moisture content.
“Our medium 23# has been at 9.0–9.06, so right where it should be. We are not utilizing our corrugator sensors to check temps like we should be. That being said, we are still not too far out of line. Die cut slots are clean, and print is acceptable.
“However, humidity levels are starting to creep back up, so we are trying to get ahead of it before cold temps are back. We know that will dry out our board a bit.
“This is a snapshot of our levels for the past two weeks” (see chart at bottom left).
Our Response
“You’re doing everything right. That’s the moisture instrument I always recommend. Is your medium coming to you with 1%–1.5% higher moisture content (MC) than the liner?
“These values seem a little low for combined board given that you are combining and converting 100% recovered fiber containerboards. However, if your die cuts and slots are clean, your scores are not cracking, [and] you’re running flat board and getting good print, then it sounds like the numbers are working for you. Since the MC seems to be a bit low, you’ll really want to keep an eye on the level when the temps change.
“As you mentioned in our call, the TAPPI standard 0304-37 should provide some good information, as well.”
For more on this or any other subject, you are always welcome to contact me at any time to discuss any technical concerns.
Ralph Young is the principal of Alternative Paper Solutions and is AICC’s technical advisor. Contact Ralph directly about technical issues that impact our industry at askralph@AICCbox.org.
