Alvin C. "Al" Hertel, 89, of Mercer, died peacefully Thursday morning, April 27, 2017, in his home, surrounded by his loving family.     He was born Dec. 13, 1927, in Deerfield, Ill., son of the late William and Anna (Bock) Hertel, and graduated from Highland Park High School in Highland Park, Ill.  He served stateside in the U.S. Navy in Pensacola, Fla. for a year, then following his honorable discharge, for eight years in the Naval Reserve.      He was united in marriage to the former Gertrude E. "Gertie" Barber on March 5, 1948, in Deerfield.      Al was employed as plant foreman for Underwriters Laboratory in Northbrook, Ill. for 30 years, retiring and moving to Mercer in 1979. He enjoyed hunting, fishing and woodworking.      Surviving are his wife, Gertie, of 69 years; son, Carl (Donna), Mercer; five grandchildren, Kimberly (Greg) Bortz, Butternut, Kevin Hertel, Weston, Kelly (Hank) Joustra, Mercer, and Derek (Kristin) Hertel and Nicole Hertel, both of Seattle, Wash.; 10 great-grandchildren, Taylar, Cassy, Grace, Cody, Jake, Hana, Ben, Levi, Sadee and Kyler; and numerous nieces and nephews.      Besides his parents, Al was preceded in death by a son, Donald; granddaughter, Cori Hertel, in 1975; and three brothers, Paul, Lester and Bill.      Out of respect for his wishes, cremation has taken place.      Services and inurnment in the Mercer Cemetery will be held at a later date.      Arrangements were entrusted to McKevitt-Patrick Funeral Home and Cremation Services of Ironwood, Mich. Al's obituary can be viewed online and condolences given to his family at mckevittpatrick funeralhome.com.