April 11, 2025
Ron asks:
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% ave.
We’re using a Denver Moisture reader. We cut circles of combined board, place into the fixture, 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 COA’s 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.
You’re doing everything right. That’s the instrument I always recommend. Is your medium coming to you with 1-1.5 percent higher Moisture Content (MC)?
These values seem a little low for combined board given that you are combining and converting 100% recovered fibre containerboards. However, if your die cuts and slots are clean, your scores are not cracking, 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.
— Ralph
