MEMBER: Can you give me a publication that documents the typical pounds of starch per thousand square feet of combined board.
RALPH YOUNG: The Institute of Paper Science and Technology has published Corrugated Medium: Its Influence on Box Plant Operations and Combined Board Properties and Packaging Performance and issued May 1994. In Chapter Seven on Bonding Theory and on page 54, the discussion mentions an application rate of 2.2 pounds per thousand square feet.

 MEMBER'S QUESTION:

 Good morning Ralph! Can you do me a favor? Do you have the "standard" ring crush values for KLB and recycled liner board/medium? In particular 42# liner?  Specifically, my customer is considering switching to Leipa LUX 41# (ring crush 72) from MWV (coated white top) 40# ( ring crush 92).  I do not have the BCT results yet but we could always beef up the medium or inside liner to improve box strength.

ASKRALPH! RESPONDS:

The AF&PA collects these values monthly and publishes these numbers semi-annually for the member mills that submit their test results.  There is no distinction between kraft and recycled linerboard and semichemical and recycled mediums. I usually have values for specific mills and companies.  Can you be more specific for me so that I can develop a unique answer for you?

In the US, 42# linerboard ranges from 70 to 98 CD ring crush.  Experience tells me that the low end would typically be a 100% recycled sheet and the top end an almost 100% virgin kraft sheet.  When you have the BCT results let me know and I will tell you how to engineer the most cost effective corrugated structure.  There is a load sharing mechanical element that needs to be taken into consideration.