Following the retirement of James Campbell, Darren Bianchi has been appointed president of the Radiant Color Division of Magruder Color Company.      After more than 42 years with Radiant Color, Mr. Campbell announced his retirement, effective April 1. Mr. Campbell assumed much of the responsibility for the company’s manufacturing development. His understanding of the fluorescent pigment industry, both in manufacturing and marketing, provided a strong base for Radiant’s ability to respond to ...