When There's No Cure

First, some of the chemistry

In my initial discussion with Mark Hahn, VP of sales and marketing for AAA Press International (Arlington Heights, Ill.), he gave an overview of the ink chemistry, and therefore, what the UV curing equipment is targeted to accomplish. According to Hahn, inks and coatings contain three key elements for proper curing—monomers, oligomers, and photoinitiators. Monomers and oligomers are the reactive components, while photoinitiators are the components activated by the UV energy to set off the curing process for the inks/coatings. "Typically, ink manufacturers will put specific photoinitiators into the inks for surface cure, depth of cure, bonding, and other ink features," explains Hahn. "A standard medium-pressure, mercury vapor lamp will produce a specific intensity curve with peak irradiance being at 365 nanometers (nm). Ink manufacturers try to match their ink chemistry to this curve for optimum curing performance."