The CNS 12425-2011 standard specifies a test method for paper transparency. The standard applies to various types of paper, especially transparent and translucent papers. The standard details the instruments and equipment required for testing, including transparency meters and photometers, among others. The testing process involves placing paper samples in a specific test environment to assess their transparency by measuring the intensity of rays of light passing through the paper. The standard provides paper producers and users with standardized transparency measurement methods that ensure paper's Optical Properties in applications such as printing, Encasement, etc.