ASTM D8042-18(2023) PDF

SIGNIFICANCE AND USE 5.1 This test method is designed to determine the temperature at which the Wet Blue or Wet White specimen experiences shrinkage. In this test method, shrinkage occurs as a result of hydrothermal denaturation of the collagen protein molecules which make up the fiber structure of the Wet Blue or Wet White. The shrinkage temperature of Wet Blue or Wet White is influenced by many different factors, most of which appear to affect the number and nature of crosslinking interactions between adjacent polypeptide chains of the collagen protein molecules. The value of the shrinkage temperature of Wet Blue or Wet White is commonly used as an indicator of the type of tannage or the degree of tannage, or both, of that particular Wet Blue or Wet White (especially for the more hydrothermally stable tannages such as chrome tannage). SCOPE 1.1 This test method covers the determination of the shrinkage temperature of all types of Wet Blue and Wet White. The heating medium is water when the shrinkage temperature is at or below 98 °C. The heating medium is a glycerine-water solution when the shrinkage temperature is above 98 °C. 1.2 The values stated in SI units are to be regarded as the standard. The values in parentheses are for information only. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.