The Turn Of The Century Electrotherapy Museum http://www.electrotherapymuseum.com Tar + Paraffin Wax Insulated Pancake Coil Zywiec - Prized Original Polish Beer. Oh...and a Pancake Coil insulated with Paraffin Wax and Tar! Underside of coil - note the glass stir rods used to raise the coil from the bottom of the coil Primary Coil added.  The insulation looks more black than the EPDM rubber! Sparky...