This part of ISO 12625 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.They are listed and explained in Annex A.
This part of ISO 12625 also gives recommendations regarding relevant opotial 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 opotical measurements of creped products and embossed products, where special special precautions may be necessary if the test-piece surfaces are uneven and if the materials are bulky,so that air is entrappen between the sheets.