ASTM D8042-18(2023)
(Test Method)Test Method for Shrinkage Temperature of Wet Blue and Wet White
Test Method for Shrinkage Temperature of Wet Blue and Wet White
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.
General Information
Relations
Standards Content (Sample)
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.
Designation: D8042 − 18 (Reapproved 2023)
Test Method for
Shrinkage Temperature of Wet Blue and Wet White
This standard is issued under the fixed designation D8042; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.2 Definitions of Terms Specific to This Standard:
3.2.1 shrink, v—to contract or become smaller.
1.1 This test method covers the determination of the shrink-
3.2.2 shrinkage, n—the temperature at which noticeable
age temperature of all types of Wet Blue and Wet White. The
shrinkage occurs when a Wet Blue or Wet White specimen is
heating medium is water when the shrinkage temperature is at
gradually heated in an aqueous medium.
or below 98 °C. The heating medium is a glycerine-water
solution when the shrinkage temperature is above 98 °C.
4. Summary of Test Method
1.2 The values stated in SI units are to be regarded as the
4.1 A Wet Blue or Wet White specimen is thoroughly
standard. The values in parentheses are for information only.
soaked in the aqueous medium that will be used to heat the
1.3 This standard does not purport to address all of the
specimen for this test method. This specimen is then fastened
safety concerns, if any, associated with its use. It is the
between two clamps (one fixed and one movable) and im-
responsibility of the user of this standard to establish appro-
mersed in the aqueous medium (see Fig. 1). The aqueous
priate safety, health, and environmental practices and deter-
medium is gradually heated until the specified temperature is
mine the applicability of regulatory limitations prior to use.
reached without shrinkage or until shrinkage is indicated by a
1.4 This international standard was developed in accor-
deflection of the dial needle which is attached to the movable
dance with internationally recognized principles on standard-
clamp.
ization established in the Decision on Principles for the
5. Significance and Use
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
5.1 This test method is designed to determine the tempera-
Barriers to Trade (TBT) Committee.
ture at which the Wet Blue or Wet White specimen experiences
shrinkage. In this test method, shrinkage occurs as a result of
2. Referenced Documents
hydrothermal denaturation of the collagen protein molecules
2.1 ASTM Standards:
which make up the fiber structure of the Wet Blue or Wet
D1517 Terminology Relating to Leather
White. The shrinkage temperature of Wet Blue or Wet White is
D6076 Test Method for Shrinkage Temperature of Leather
influenced by many different factors, most of which appear to
affect the number and nature of crosslinking interactions
3. Terminology
between adjacent polypeptide chains of the collagen protein
3.1 Definitions—For definitions of general leather terms
molecules. The value of the shrinkage temperature of Wet Blue
used in this test method, refer to Terminology D1517.
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
This test method is under the jurisdiction of ASTM Committee D31 on Leather Blue or Wet White (especially for the more hydrothermally
and is the direct responsibility of Subcommittee D31.02 on Wet Blue.
stable tannages such as chrome tannage).
Current edition approved Sept. 1, 2023. Published September 2023. Originally
approved in 2016. Last previous edition approved in 2018 as D8042 – 18. DOI:
6. Apparatus
10.1520/D8042-18R23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 6.1 Stand, for supporting the testing equipment.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
6.2 Indicating Device, either of the two devices listed as
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. follows:
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D8042 − 18 (2023)
indicator shall have a spindle capable of attachment to the
specimen and to the adjustable weight assembly.
6.3 Immersion Heater, 250 W to 500 W, with a heating
element not longer than 140 mm (5 ⁄2 in.) and a depth of
immersion not in excess of 152 mm (6 in.).
6.4 Variable Speed Stirrer, with small blades.
6.5 Spring-loaded Clamps, (alligator type), two, mounted
vertically one above the other and sufficiently far apart for
gripping the full width of the specimen at the ends. The bottom
clamp shall be fastened to the end of a U-shaped rod that can
be turned sideways. The upper clamp shall be movable
sideways as well as up and down.
6.6 Metal Supporting Plate, with apertures for the stirrer,
thermometer, immersion heater, and the rod fastened to the
upper specimen clamp.
6.7 Variable Transformer, capable of controlling the rate of
heating (3 °C ⁄min to 5 °C ⁄min) of the aqueous medium and
capable of maintaining a temperature of 98 °C 6 0.5 °C.
6.8 Thermometer, capable of reading from 0 °C to 100 °C in
1 °C increments with a tolerance of 60.5 °C.
6.9 Tall-form 1 L Beaker, for holding the aqueous heating
medium.
6.10 Lead Shot.
6.11 Indicating Device, attached to the upper (movable)
clamp and equipped with an adjustable weight assembly
mounted over a pulley. The weight assembly shall consist of a
small bottle (with a lid) containing lead shot that shall be
attached to the string running over the pulley. The weight
assembly shall be approximately 178 g to counterbalance the
weight of the clamp, to overcome any inertia or friction of the
indicating device, and to maintain the specimen under a slight
tension. The weight shall be adjusted accordingly, so that it will
not
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