Inside Cracking on Singleface

Fern asks:

I am curious if there is anything written regarding inside cracking on the singleface liner and how it doesn’t take away from the structural aspects of the box, or if there is an industry guideline that I can refer to.

Of course we do our best to eliminate it all together, but now we are working with more & more recycled liners (some heavily recycled) and shorter fibers, we continue to battle this.

You are not alone in this struggle.  And it’s becoming that time of year when this becomes common for many cold weather converters.

One thing we need to remember is that recycled paper gives up moisture much faster than papers made with virgin fibers. When relative humidity drops below 50% the normal board moisture content can plummet leading to a more brittle liner. And, the short fibers of recycled paper create a structure that is more brittle to begin with than long fibre virgin.

Many converters use and/or have experimented with different score profiles and for virgin and recycled paper. The more aggressive, or sharper the profile the more likely to crack the liner. While 4pt crease may be typical, 6 or 8 point can be used to distribute the pressure across the surface.

AICC published a White Paper on Score Cracking a few years back. Click here to download the White Paper. The White paper is free to AICC Members.

We have visited this topic many times in Ask Ralph. Type “Cracking Scores” or “Cracking liners” in the “Search Ask Ralph” field on this blog.

— Ralph

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