MEMBER'S QUESTION:

Hi Ralph,

Occassionally, the question arises "What is a typical or appropriate warranty period for corrugated products?"  We certainly don't advocate forcing customers to accept sub par quality products, however, there are situations which arise where the discussion comes up. Is it different for die cut vs. flexo work?  What about printing, litho lam. etc?
 
This relates to finished boxes that sits at a customer's site for an extended period of time. When finally unbanded for use, they may experience cracking which may have occurred due to their storage conditions,  or in one case recently, a printed and glued "weekender" style display had a weakening of the board in piece just below the glue tab of the piece above.  This compression caused weakness.  They had sat there for 4 months. We probably had crushed them in our banding process, however, it;'s possible that due to time, they took a prominent set that would not have occurred in a shorter time frame. The question was asked " What is the life expectancy or warranty period for a product such as this"  We resoved it by replacing the product at our expense,  but it brings up a few interesting points.
 
 
ASKRALPH RESPONDS:

Great to hear from you.  Thank you for the question.

Your question somewhat precedes an article in the May/June issue of BoxScore.  Review, distribute and save the chart on the Expected Values of Combined Board.  As long as the corrugated products maintain their flat crush, edge crush, and pin adhesion strength values close to what they were when the products were manufactured, then the aged products are the same as new production.

What happens during the aging process, given constant humidity, is that the paper “dries” out and become brittle.  The changes in the lignin structure (the brown stuff that told the fibres together in the trees and impart the brown hue to corrugated) and the loss of fibre to fibre bonding is a little complicated than can be explained here.  Board does not improve with age, but it does have a significant life expectancy.  You need to have the corrugated tested to determine suitability.  Case erection and cracking score can also be an issue with aged board.  Test! Test! Test!  There is no need to guess.