In 1950, he joined the family business and rose through its ranks to become president of the company. In addition to syrup, which it began producing in 1901, the firm made starch, bleach and laundry rinse, which it distributed in the eastern United States from its plant in the 1400 block of Key Highway in South Baltimore.
Mr. Mangels retired from the company in 1985 after it was sold.
He was a former member of the board of Light Street Savings & Loan and the Kent & Queen Anne Hospital. He also had been a founding board member of Chesapeake Bank & Trust Co. in Chestertown.
A former Ruxton resident, he moved in 1972 to a farm in Tolchester and, since 2010, had been living in Chestertown.
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Mr. Mangels and his wife were avid hunters and supporters of the Washington College lacrosse team — they began the annual Shoreman Stick Supporters Fish Fry.
Graveside services are private.
He is survived by three sons, Roger Neilson “Neil” Mangels of Chestertown, Walter B. “Tom” Mangels III of Shadyside and Carl B. Mangels of Rock Hall; a daughter, Robin Schepf of Monkton; seven grandchildren; and five great-grandchildren.