Classification and Effects of Variations in Fiducial State of a Coating Substrate

Ted Lightfoot, Ted Lightfoot LLC

Non-planarities (also known as bagginess, layflat issues, or planarity issues) are known causes of coating upsets and other defects that arise from variations in the fiducial state of the coating substrate.  While the problems from dealing with a non-uniform substrate are known, the nomenclature to describe them is uncontrolled.  The best efforts to standardize the nomenclature have been focused on distinguishing two types of non-planarities: cockle and buckle (see references 1 and 2) .  However, there are more than two classes of variations in fiducial state that can lead to non-planarity and there are variations in fiducial state that can affect coating quality without introducing a non-planarity. This paper gives a classification scheme useful for illustrating the breadth of the problem.  The hope is to establish a working group to standardize the terminology for these issues across multiple industries.

1. Neil Steinberg Converting Magazine 18(1) pg.36 (Jan 2000)
2. E. J. Lightfoot, Chapter “Extrusion Coating and Lamination Defects”, in Ultimate Web and Roll Troubleshooting Guide, R. Duane Smith, Ed, Atlanta: TAPPI Press 2013