Some Architectural Specifications require steel frames to be back-coated with a "bituminous" product for corrosion protection and sound control. The term “bituminous” is defined as an asphalt or tar material obtained as a residue from heat refined petroleum. For years it was not recommended by the Steel Door Institute for frames to be factory back-coated due to issues with packaging, shipping and handling. This procedure was more effectively accomplished at the jobsite by the contractor or appropriate trade immediately prior to installation of the frame.
Modern materials now offer manufacturers the opportunity to back-coat frames with a more user and environmentally friendly product. Some of these coating s are VOC (Volatile Organic Compounds) free and do not present the handling issues common to bituminous products. Today, multiple SDI manufacturers offer the option of factory back-coated frames which utilize these newer materials.