ASTM D6716-08(2020)

Standard Test Method for Total Ash in Wet Blue or Wet White

SIGNIFICANCE AND USE
5.1 This test method is useful in determining the approximate amount of nonvolatile inorganic material in wet blue. This may be in the form of salts or oxides of the elements. In a mixed-chrome tannage, the approximate percentage of other elements in the wet blue may be determined by subtracting the chromic oxide that may be conveniently determined on the ash. (See Test Method D6714.)  
5.2 The specified temperature of 600°C is high enough to produce a reproducible result but it does not completely dehydrate such oxides as aluminum oxide (Al2O3) and chromic oxide (Cr2O3). Likewise, such salts as sulfates and phosphates may be incompletely dehydrated, and if alkalis and chromium are present simultaneously, oxidation to chromate may occur. Therefore, caution is advised in drawing conclusions based on quantitative relations of the elements.
SCOPE
1.1 This test method covers the determination of total ash in wet blue and wet white.  
1.2 For total ash in wet white, the procedure is identical; substitute wet white for wet blue in the standard.  
1.3 Total ash in wet blue may be reported upon a number of different bases (for example, fat-free, moisture-free, as received, excluding chromium, and so forth). Before proceeding with any tests, it is very important to determine upon which basis that the total ash is to be reported and to identify all other test methods that will be required to be executed in order to achieve the determined reporting method.  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 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.  
1.6 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: 31-Mar-2020
• ICS: 59.140.30 - Leather and furs
• Technical Committee: D31 - Leather
• Drafting Committee: D31.02 - Wet Blue

Relations

• Replaces: ASTM D6716-08(2013) - Standard Test Method for Total Ash in Wet Blue or Wet White
• Effective Date: 01-Apr-2020
• Refers: ASTM D6658-08(2020) - Standard Test Method for Volatile Matter (Moisture) of Wet Blue by Oven Drying
• Effective Date: 01-Apr-2020
• Refers: ASTM D6659-10(2015) - Standard Practice for Sampling and Preparation of Wet Blue for Physical and Chemical Tests
• Effective Date: 01-Dec-2015
• Refers: ASTM D6714-01(2015) - Standard Test Method for Chromic Oxide in Ashed Wet Blue (Perchloric Acid Oxidation)
• Effective Date: 01-Dec-2015
• Refers: ASTM D6658-08(2013) - Standard Test Method for Volatile Matter (Moisture) of Wet Blue by Oven Drying
• Effective Date: 01-May-2013
• Refers: ASTM D3495-10 - Standard Test Method for Hexane Extraction of Leather
• Effective Date: 01-Nov-2010
• Refers: ASTM D6659-10 - Standard Practice for Sampling and Preparation of Wet Blue for Physical and Chemical Tests
• Effective Date: 01-Oct-2010
• Refers: ASTM D6714-01(2010)e1 - Standard Test Method for Chromic Oxide in Ashed Wet Blue (Perchloric Acid Oxidation)
• Effective Date: 01-Oct-2010
• Refers: ASTM D6658-08 - Standard Test Method for Volatile Matter (Moisture) of Wet Blue by Oven Drying
• Effective Date: 01-Nov-2008
• Refers: ASTM D6659-08 - Standard Practice for Sampling and Preparation of Wet Blue for Physical and Chemical Tests
• Effective Date: 01-Sep-2008
• Refers: ASTM D6659-01(2007) - Standard Practice for Sampling and Preparation of Wet Blue for Physical and Chemical Tests
• Effective Date: 01-Sep-2007
• Refers: ASTM D6658-01(2006) - Standard Test Method for Volatile Matter (Moisture) of Wet Blue by Oven Drying
• Effective Date: 01-Oct-2006
• Refers: ASTM D6714-01(2006) - Standard Test Method for Chromic Oxide in Ashed Wet Blue (Perchloric Acid Oxidation)
• Effective Date: 01-Oct-2006
• Refers: ASTM D6714-01 - Standard Test Method for Chromic Oxide in Ashed Wet Blue (Perchloric Acid Oxidation)
• Effective Date: 10-Oct-2001
• Refers: ASTM D6658-01 - Standard Test Method for Volatile Matter (Moisture) of Wet Blue by Oven Drying
• Effective Date: 10-May-2001

Overview

ASTM D6716-08(2020), published by ASTM International, is a standard test method for determining the total ash content in wet blue and wet white leather. This standard is critical in assessing the amount of nonvolatile inorganic material, such as salts or oxides, present in semi-processed hides. By providing reliable procedures for quantifying total ash, including calculations for various reporting bases, this method supports quality control and material consistency in leather manufacturing.

This standard is widely recognized and utilized by laboratories and manufacturers working with chromium-tanned (wet blue) or non-chromium tanned (wet white) leathers.

Key Topics

• Total Ash Determination: Outlines the procedures to measure total ash in wet blue or wet white samples through ignition in air at 600°C until a constant mass is achieved.
• Reporting Bases: Specifies options for expressing ash content, such as fat-free, moisture-free, as-received, or excluding chromium. Users must identify the reporting basis and associated required test methods prior to analysis.
• Sample Preparation: Requires following specified ASTM practices for sampling and preparation to ensure representativity and accurate results.
• Significance and Use: Provides insights into the proportion of inorganic materials in the semi-processed hides, important for understanding chemical composition and monitoring manufacturing consistency.
• Cautions in Interpretation: Notes that the 600°C temperature may not fully dehydrate some oxides or salts, and chemical reactions may occur, affecting compositional analysis accuracy for certain elements.
• International Relevance: Developed in accordance with internationally recognized standardization principles and aligned with WTO TBT Committee guidelines.

Applications

The ASTM D6716-08(2020) standard is essential in multiple areas of the leather supply chain:

• Quality Control in Leather Processing: Ensures consistent nonvolatile inorganic content in wet blue and wet white, supporting reliable tanning results and end-product quality.
• Regulatory Compliance: Helps manufacturers demonstrate conformity to industry benchmarks and export/import regulations concerning material composition.
• Research and Development: Supports scientists and technicians studying the interactions between organic leather constituents and inorganic tanning agents, leading to new processes or product improvements.
• Specification and Procurement: Provides quantitative data for buyers and suppliers to verify material consistency and specification adherence in supply agreements.
• Process Troubleshooting and Optimization: Enables identification of variance in ash content that may indicate process deviations, contamination, or material inconsistencies.

Related Standards

To ensure comprehensive analysis and accurate reporting, ASTM D6716-08(2020) references and is complemented by several other ASTM standards:

• ASTM D6714: Test Method for Chromic Oxide in Ashed Wet Blue - provides details for the determination of chromic oxide, often used in conjunction with D6716 for chrome-tanned leathers.
• ASTM D3495: Test Method for Hexane Extraction of Leather - used when ash content is to be reported on a fat-free basis.
• ASTM D6658: Test Method for Volatile Matter (Moisture) of Wet Blue by Oven Drying - necessary for moisture-free ash content reporting.
• ASTM D6659: Practice for Sampling and Preparation of Wet Blue and Wet White for Physical and Chemical Tests - ensures representative sample selection.

Practical Value

Implementing ASTM D6716-08(2020) leads to enhanced process control, product consistency, and compliance across the leather manufacturing industry. Its standardized procedures for total ash assessment equip manufacturers, laboratories, and quality assurance professionals with essential data for making informed decisions, optimizing processes, and maintaining high industry standards.

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: D6716 − 08 (Reapproved 2020)
Standard Test Method for
Total Ash in Wet Blue or Wet White
This standard is issued under the fixed designation D6716; 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 D6714 Test Method for Chromic Oxide in Ashed Wet Blue
(Perchloric Acid Oxidation)
1.1 This test method covers the determination of total ash in
wet blue and wet white.
3. Terminology
1.2 For total ash in wet white, the procedure is identical;
3.1 Definitions:
substitute wet white for wet blue in the standard.
3.1.1 The terms and definitions employed within this test
1.3 Total ash in wet blue may be reported upon a number of
method are commonly used in normal laboratory practice and
different bases (for example, fat-free, moisture-free, as
require no special comment.
received, excluding chromium, and so forth). Before proceed-
ingwithanytests,itisveryimportanttodetermineuponwhich
4. Summary of Test Method
basis that the total ash is to be reported and to identify all other
4.1 Theweighedsampleisignitedinairat600 625°Cuntil
test methods that will be required to be executed in order to
constant mass is attained. The weighed residual matter is
achieve the determined reporting method.
termed “ash” and is calculated as a percentage of the original
1.4 The values stated in SI units are to be regarded as
sample.
standard. No other units of measurement are included in this
5. Significance and Use
standard.
1.5 This standard does not purport to address all of the
5.1 This test method is useful in determining the approxi-
safety concerns, if any, associated with its use. It is the mate amount of nonvolatile inorganic material in wet blue.
responsibility of the user of this standard to establish appro-
This may be in the form of salts or oxides of the elements. In
priate safety, health, and environmental practices and deter- a mixed-chrome tannage, the approximate percentage of other
mine the applicability of regulatory limitations prior to use.
elements in the wet blue may be determined by subtracting the
1.6 This international standard was developed in accor- chromicoxidethatmaybeconvenientlydeterminedontheash.
dance with internationally recognized principles on standard-
(See Test Method D6714.)
ization established in the Decision on Principles for the
5.2 The specified temperature of 600°C is high enough to
Development of International Standards, Guides and Recom-
produce a reproducible result but it does not completely
mendations issued by the World Trade Organization Technical
dehydratesuchoxidesasaluminumoxide(Al O )andchromic
2 3
Barriers to Trade (TBT) Committee.
oxide (Cr O ). Likewise, such salts as sulfates and phosphates
2 3
may be incompletely dehydrated, and if alkalis and chromium
2. Referenced Documents
are present simultaneously, oxidation to chromate may occur.
2.1 ASTM Standards:
Therefore, caution is advised in drawing conclusions based on
D3495 Test Method for Hexane Extraction of Leather
quantitative relations of the elements.
D6658 Test Method for Volatile Matter (Moisture) of Wet
Blue by Oven Drying
6. Apparatus
D6659 Practice for Sampling and Preparation of Wet Blue
6.1 Crucible, 30- to 50-mL, high-form, platinum or porce-
and Wet White for Physical and Chemical Tests
lain.
6.2 Electric Muffle Furnace, with controller or rheostat and
This test method is under the jurisdiction ofASTM Committee D31 on Leather
pyrometer, capable of maintaining a temperature of 600 6
and is the direct responsibility of Subcommittee D31.02 on Wet Blue.
Current edition approved April 1, 2020. Published April 2020. Originally 25°C.
approved in 2001. Last previous edition approved in 2013 as D6716 – 08(2013).
6.3 Dessicator, of appropriate size and charged with fresh
DOI: 10.1520/D6716-08R20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or dessicant.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
6.4 Analytical Balance, capable of accurate weighings to
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. within 0.001 g.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6716 − 08 (2020)
minutes, and filter the suspension through an ashless high-retention filter
7. Test Specimen
paper. Transfer the paper and insoluble residue to the crucible and ignite
7.1 The specimen shall consist of 2 to 10 g of wet blue from
at 600 6 25°C as described above. Cool, add the filtrate to the crucible,
the composite sample, prepared in accordance with Practice
evaporate carefully to dryness, then ignite at 600 6 25°C to constant mass
as described previously.
D6659.
NOTE 1—Typicall
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