ISO 12625-7:2007 specifies test methods for the instrumental determination of optical properties of tissue paper and tissue products. The various test methods that are available have been, or are being, developed as International Standards.
ISO 12625-7:2007 also gives recommendations regarding relevant optical properties to be measured for different grades of tissue paper and tissue products and gives specific instructions for the preparation of test pieces (single-ply, multi-ply products) and for the optical measurements of creped products and embossed products, where special precautions may be necessary if the test-piece surfaces are uneven and if the materials are bulky, so that air is entrapped between the sheets.