ASTM D6409-99(2020)

Standard Practice for Color Tests with Sheepskin Skiver

SIGNIFICANCE AND USE
5.1 This practice provides a standard procedure for comparing the color of leather tanned with different tanning extracts or mixtures of extracts or for monitoring the color consistency of tannery liquors.
SCOPE
1.1 This practice covers making color tests of all types of vegetable tanning extracts and of vegetable tanning materials to determine the color imparted to tanned skins.  
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard.  
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

• Status: Published
• Publication Date: 30-Nov-2020
• ICS: 59.140.10 - Processes and auxiliary materials
• Technical Committee: D31 - Leather
• Drafting Committee: D31.01 - Vegetable Leather

Relations

• Refers: ASTM D1517-15 - Standard Terminology Relating to Leather
• Effective Date: 01-Dec-2015
• Refers: ASTM D1517-10 - Standard Terminology Relating to Leather
• Effective Date: 01-Oct-2010
• Refers: ASTM D6405-99(2009) - Standard Practice for Extraction of Tannins from Raw and Spent Materials
• Effective Date: 01-Apr-2009
• Refers: ASTM D4901-99(2009) - Standard Practice for Preparation of Solution of Liquid Vegetable Tannin Extracts
• Effective Date: 01-Apr-2009
• Refers: ASTM D4905-99(2009) - Standard Practice for Preparation of Solution of Solid, Pasty and Powdered Vegetable Tannin Extracts
• Effective Date: 01-Apr-2009
• Refers: ASTM D1517-06 - Standard Terminology Relating to Leather
• Effective Date: 01-Oct-2006
• Refers: ASTM D1517-04 - Standard Terminology Relating to Leather
• Effective Date: 01-Sep-2004
• Refers: ASTM D1517-04e1 - Standard Terminology Relating to Leather
• Effective Date: 01-Sep-2004
• Refers: ASTM D1517-99(2004) - Standard Terminology Relating to Leather
• Effective Date: 01-Apr-2004
• Refers: ASTM D4905-99(2004) - Standard Practice for Preparation of Solution of Solid, Pasty and Powdered Vegetable Tannin Extracts
• Effective Date: 01-Apr-2004
• Refers: ASTM D6405-99(2004) - Standard Practice for Extraction of Tannins from Raw and Spent Materials
• Effective Date: 01-Apr-2004
• Refers: ASTM D4901-99(2004) - Standard Practice for Preparation of Solution of Liquid Vegetable Tannin Extracts
• Effective Date: 01-Apr-2004
• Refers: ASTM D1517-99 - Standard Terminology Relating to Leather
• Effective Date: 10-May-1999
• Refers: ASTM D4901-99 - Standard Practice for Preparation of Solution of Liquid Vegetable Tannin Extracts
• Effective Date: 10-May-1999
• Refers: ASTM D4905-99 - Standard Practice for Preparation of Solution of Solid, Pasty and Powdered Vegetable Tannin Extracts
• Effective Date: 10-May-1999

Overview

ASTM D6409-99(2020) - Standard Practice for Color Tests with Sheepskin Skiver establishes a reliable procedure for evaluating and comparing the color imparted to tanned leather by various vegetable tanning extracts or mixtures. This standard is critical for ensuring color consistency in leather production and for monitoring the quality of tannery liquors. Developed by ASTM International, it aligns with global standardization principles, supporting harmonization and quality management within the leather industry.

Key Topics

• Testing Methodology: The standard provides step-by-step guidance for conducting color tests using pickled sheepskin skiver as the substrate. The procedures cover sample preparation, treatment with tanning liquor, and evaluation of color results.
• Vegetable Tanning Extracts: Focuses on all types of vegetable tanning materials, emphasizing the importance of understanding the color characteristics imparted by different tanning agents.
• Color Comparison: Facilitates direct comparison between different tanning extracts, as well as monitoring color consistency within a single tannery batch or between different production runs.
• Sample Preparation: Details rigorous preparation, including the washing and conditioning of the skiver, ensuring the method yields repeatable and unbiased color results.
• Safety and Environmental Responsibility: Reminds users to adhere to proper safety, health, and environmental practices when applying the standard in laboratory and industrial settings.

Applications

• Quality Control in Tanneries: Used by tannery professionals to maintain and control the color quality of vegetable-tanned leather, preventing inconsistencies and supporting uniform product appearance.
• Research and Development: Assists researchers in comparing the effects of new or modified vegetable tanning extracts, helping to optimize formulations for desired color outcomes.
• Supplier Evaluation: Enables leather manufacturers to assess the color performance of tanning extracts received from different suppliers, supporting procurement decisions.
• Batch-to-Batch Consistency: Provides a standardized approach to monitor production lots and ensure uniform color across large-scale leather batches, reducing potential product rejections and customer complaints.
• Compliance and Auditing: Supports compliance with international quality standards and customer specifications by documenting objective color test results.

Related Standards

For comprehensive quality assurance and process control, ASTM D6409-99(2020) is best used alongside other relevant standards, including:

• ASTM D1517 - Terminology Relating to Leather: Provides definitions for terms used in leather processing and testing.
• ASTM D4901 - Practice for Preparation of Solution of Liquid Vegetable Tannin Extracts: Guides the preparation of liquid extract samples.
• ASTM D4905 - Practice for Preparation of Solution of Solid, Pasty and Powdered Vegetable Tannin Extracts: Covers the preparation of non-liquid extract samples.
• ASTM D6405 - Practice for Extraction of Tannins from Raw and Spent Materials: Essential for obtaining and analyzing tannin content for testing.

Practical Value

Adopting ASTM D6409-99(2020) helps organizations in the leather industry:

• Achieve consistent and repeatable color results
• Build confidence in product quality among buyers and end-users
• Minimize production defects related to color variation
• Facilitate international trade by adhering to recognized testing protocols

By integrating this standard into routine laboratory or tannery operations, companies reinforce best practices in leather color assessment and support the delivery of high-quality, visually uniform leather products.

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: D6409 − 99 (Reapproved 2020)
Standard Practice for
Color Tests with Sheepskin Skiver
This standard is issued under the fixed designation D6409; 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. Terminology
1.1 This practice covers making color tests of all types of 3.1 Definitions:
vegetable tanning extracts and of vegetable tanning materials 3.1.1 For definitions of general leather and tanning terms
to determine the color imparted to tanned skins. used in this practice refer to Terminology D1517.
3.1.2 pickled skiver—a sheepskin skiver that has been pick-
1.2 The values stated in SI units are to be regarded as
led in a solution of salt and sulfuric acid.
standard. The values given in parentheses after SI units are
3.1.3 sheepskin skiver—the grain split of a de-wooled
provided for information only and are not considered standard.
sheepskin. A pickled skiver is used for this test.
1.3 This standard does not purport to address all of the
3.1.4 tannin—an astringent substance found in the various
safety concerns, if any, associated with its use. It is the
parts of plants such as bark, wood, leaves, nuts, fruits, roots,
responsibility of the user of this standard to establish appro-
etc.
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
3.1.5 vegetable tannins—mixtures of substances (natural
1.4 This international standard was developed in accor-
products) obtained from plant tissues by water extraction
dance with internationally recognized principles on standard-
which have the chemical and physical properties necessary to
ization established in the Decision on Principles for the
convert animal hides and skins into leather.
Development of International Standards, Guides and Recom-
4. Summary of Practice
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
4.1 Aspecimen of pickled skiver is tanned with a sample of
vegetable tanning liquor in order to determine the color which
2. Referenced Documents
will be imparted to a clear, clean hide or skin that is tanned
2.1 ASTM Standards: with this tanning liquor.
D1517 Terminology Relating to Leather
5. Significance and Use
D4901 Practice for Preparation of Solution of Liquid Veg-
etable Tannin Extracts
5.1 This practice provides a standard procedure for compar-
D4905 Practice for Preparation of Solution of Solid, Pasty ingthecolorofleathertannedwithdifferenttanningextractsor
and Powdered Vegetable Tannin Extracts
mixtures of extracts or for monitoring the color consistency of
D6405 Practice for Extraction of Tannins from Raw and tannery liquors.
Spent Materials
6. Apparatus and Reagents
2.2 ALCA Methods:
6.1 Pickled Sheepskin Skiver, specially and consistently
A40 Color Tests with Sheepskin Skiver
selected for the color test.
6.2 Borax, commercial grade such as may be used in a
This practice is under the jurisdiction ofASTM Committee D31 on Leather and
tannery.
is the direct responsibility of Subcommittee D31.01 on Vegetable Leather. This test
method has been adapted from and is a replacement for MethodA40 of the Official
6.3 Containers, 10 and 3 L capacity and made of suitable
Methods of the American Leather Chemists Association.
material to be resistant to the chemicals and materials used in
Current edition approved Dec. 1, 2020. Published December 2020. Originally
the tanning procedure employed by this practice.
approved in 1999. Last previous edition approved in 2014 as D6409 – 99 (2014).
DOI: 10.1520/D6409-99R20.
6.4 Acetic Acid, glacial, commercial grade.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
6.5 Sodium Acetate, crystal, commercial grade.
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. 6.6 Sodium Chloride, crystal, commercial grade.
Official Methods of the American Leather Chemists Association. Available
6.7 Shake Bottles, 0.95 L(32 oz), with rubber stoppers. The
from the American Leather Chemists Association, University of Cincinnati, P.O.
Box 210014, Cincinnati, OH 45221-0014. bottles shall be approximately 21.6 cm (8.5 in.) overall height
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6409 − 99 (2020)
and 8.9 cm (3.5 in.) diameter. One quart canning jars (Mason- 9. Procedure for Making Color Tests
type) with plastic screw-on lids work well.
9.1 Remove the salt from the skiver sample 10 by 15 cm (4
6.8 Shaking Machine,rotatingtype,equippedtohold0.95L
by6in.)byshakingwithfourchangesofdistilledwater,of500
(32 oz) bottles for end-over-end agitation of hide powder and
mL each and at 23 to 25 °C, in a s
...