This method provides a measure of diffuse opacity (paper backing) of white and near-white papers, previously known as printing opacity. The method may be employed for colored papers on condition that their reflectance (paper backing) is greater than 20% and their diffuse opacity (paper backing) is greater than 45% (1). The method is not suitable for highly transparent papers such as glassine. This method employs d/0 geometry, illuminant C, and paper backing whereas TAPPI T 425 Opacity of Paper employs 15/d geometry, illuminant A, both 89% reflectance backing and paper backing.