I have some corona treated film substrates that have been sitting in inventory for months. How quickly does the benefit of corona treatment dissipate?
Apr 28, 2020

Unfortunately, a film's dyne level increase due to corona treatment is not permanent. Factors that cause this decay include additives migrating to a film's surface, contamination from handling, the environment (such as humidity/storage conditions), and natural decay (time). Different films will decay at different rates; dyne tests provide a quick check of the treatment level. At one end, a polypropylene film may start at 40 dynes, but within 30 days or less it could go down to 34 dynes because of additives migrating back up to the surface. On the opposite end is a PET film treated to 56 dynes, and after 30 days it could still be at 50 dynes. So, the bottom line is that different films treat differently and also retain their surface treatment at different rates. A solution to this erosion in dyne level is to bump treat prior to converting. Bump treating refers to the installation of a corona treater(s) inline and stationed immediately prior to printing. [The Experts thank Enercon Industries, a provider of corona treating equipment, for its help in answering this question.]

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