ASTM D3897-18

Standard Test Method for Calculation of Basicity of Chrome Tanning Liquors

SIGNIFICANCE AND USE
3.1 Basicity is a ratio. In any chromic salt solution, the electrovalence of the chromium (+3) is satisfied by the hydroxyl ions and by acid ions. The extent to which this electravalence is satisfied by the hydroxyl ions, expressed as a percentage, is the basicity. The basicity of a chrome tanning liquid is closely related to the tanning behavior of the solution.
SCOPE
1.1 This test method is intended to show how the results of the chromium analysis (Test Methods D3898 or D6019) and the acidity determination (Test Method D3913) can be combined to permit calculation of the basicity of a chrome tanning liquor.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this 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: 31-Aug-2018
• ICS: 59.140.10 - Processes and auxiliary materials
• Technical Committee: D31 - Leather
• Drafting Committee: D31.06 - Chemical Analysis

Relations

• Replaces: ASTM D3897-17 - Standard Practice for Calculation of Basicity of Chrome Tanning Liquors
• Effective Date: 01-Sep-2018
• Refers: ASTM D3898-93(2023) - Standard Test Method for Chromic Oxide in Basic Chromium Tanning Liquors
• Effective Date: 01-Dec-2023
• Refers: ASTM D6019-20 - Test Method for Determination of Chromic Oxide in Basic Chromium Tanning Liquors (Ammonium Persulfate Oxidation)
• Effective Date: 01-Apr-2020
• Refers: ASTM D3913-03(2020)e1 - Standard Test Method for Acidity in Basic Chromium Tanning Liquors
• Effective Date: 01-Apr-2020
• Refers: ASTM D6019-15 - Test Method for Determination of Chromic Oxide in Basic Chromium Tanning Liquors (Ammonium Persulfate Oxidation)
• Effective Date: 01-Dec-2015
• Refers: ASTM D3898-93(2015) - Standard Test Method for Chromic Oxide in Basic Chromium Tanning Liquors
• Effective Date: 01-Sep-2015
• Refers: ASTM D3913-03(2015) - Standard Test Method for Acidity in Basic Chromium Tanning Liquors
• Effective Date: 01-Sep-2015
• Refers: ASTM D6019-10 - Test Method for Determination of Chromic Oxide in Basic Chromium Tanning Liquors (Ammonium Persulfate Oxidation)
• Effective Date: 01-Oct-2010
• Refers: ASTM D3898-93(2009) - Standard Test Method for Chromic Oxide in Basic Chromium Tanning Liquors
• Effective Date: 01-Apr-2009
• Refers: ASTM D3913-03(2009) - Standard Test Method for Acidity in Basic Chromium Tanning Liquors
• Effective Date: 01-Apr-2009
• Refers: ASTM D6019-96(2006) - Test Method for Determination of Chromic Oxide in Basic Chromium Tanning Liquors (Ammonium Persulfate Oxidation)
• Effective Date: 01-Oct-2006
• Refers: ASTM D3898-93(2003) - Standard Test Method for Chromic Oxide in Basic Chromium Tanning Liquors
• Effective Date: 10-May-2003
• Refers: ASTM D3913-03 - Standard Test Method for Acidity in Basic Chromium Tanning Liquors
• Effective Date: 10-May-2003
• Refers: ASTM D3898-93(1998) - Standard Test Method for Chromic Oxide in Basic Chromium Tanning Liquors
• Effective Date: 10-Jan-1998
• Refers: ASTM D3913-93(1998) - Standard Test Method for Acidity in Basic Chromium Tanning Liquors
• Effective Date: 10-Jan-1998

Overview

ASTM D3897-18 is the Standard Test Method for Calculation of Basicity of Chrome Tanning Liquors, published by ASTM International. This test method details how to combine the results of chromium content and acidity analyses to determine the basicity of chrome tanning liquors. The basicity value is significant in the leather industry, as it is closely related to the tanning behavior and quality of chromium-based tanning solutions.

This standard supports compliance with international best practices and standardization principles recognized by the World Trade Organization (WTO), making it globally relevant for leather processing laboratories and manufacturers.

Key Topics

• Basicity Definition: Basicity is defined as the percentage of chromium’s electrovalence satisfied by hydroxyl ions in a chromic salt solution, calculated using results from specific chemical analyses.
• Significance of Basicity in Tanning: The basicity of chrome tanning liquor significantly influences the tanning characteristics, affecting leather quality and process control.
• Testing and Calculation:
  • Chromic oxide content in tanning liquors is determined via ASTM D3898 or D6019.
  • Acidity is measured using ASTM D3913.
  • Basicity is then calculated, typically using the Schorlemmer system, as a percentage of chromic oxide combined with hydroxyl ions.
• Precision and Bias: The standard addresses precision (repeatability and reproducibility) of the basicity determination, cautioning users to establish high precision for optimal laboratory agreement.

Applications

The ASTM D3897-18 method is an essential tool in the leather tanning industry for:

• Quality Control: Ensuring chrome tanning liquors are within optimum basicity ranges, leading to consistent tanning results and leather quality.
• Process Optimization: Adjusting process chemistry based on calculated basicity, enabling better resource efficiency, and reducing waste.
• Compliance and Standardization: Meeting industry regulations and customer requirements by adhering to internationally recognized methods for basicity determination.
• Laboratory Analysis: Providing laboratories with a reproducible, standardized procedure for combining acidity and chromium content results to calculate liquor basicity.

By using this ASTM standard, industry professionals can ensure reliable measurement of chrome tanning liquor properties, resulting in high-quality finished leather and efficient use of chrome tanning materials.

Related Standards

Several ASTM standards are referenced for use in conjunction with ASTM D3897-18:

• ASTM D3898: Test Method for Chromic Oxide in Basic Chromium Tanning Liquors
• ASTM D3913: Test Method for Acidity in Basic Chromium Tanning Liquors
• ASTM D6019: Test Method for Determination of Chromic Oxide in Basic Chromium Tanning Liquors (Ammonium Persulfate Oxidation)

Adherence to these related standards ensures accurate inputs into the calculation of basicity and consistent, comparable outcomes across different laboratories and production sites.

By implementing ASTM D3897-18 alongside these supporting methods, industry stakeholders benefit from enhanced control, improved product quality, and adherence to international best practices in chrome tanning liquor analysis.

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: D3897 − 18
Standard Test Method for
Calculation of Basicity of Chrome Tanning Liquors
This standard is issued under the fixed designation D3897; 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 droxyl ions and by acid ions. The extent to which this
electravalence is satisfied by the hydroxyl ions, expressed as a
1.1 This test method is intended to show how the results of
percentage, is the basicity. The basicity of a chrome tanning
the chromium analysis (Test Methods D3898 or D6019) and
liquid is closely related to the tanning behavior of the solution.
the acidity determination (Test Method D3913) can be com-
bined to permit calculation of the basicity of a chrome tanning
4. Procedure
liquor.
4.1 Determine the chromic oxide as described in Test
1.2 The values stated in SI units are to be regarded as
Method D3898 or D6019. Determine the acid as described in
standard. No other units of measurement are included in this
Test Method D3913.
standard.
5. Results
1.3 This standard does not purport to address all of the
5.1 The basicity of the liquor shall be expressed according
safety concerns, if any, associated with its use. It is the
to the Schorlemmer system. In this system, the basicity is the
responsibility of the user of this standard to establish appro-
per cent of the total chromic oxide that is combined with
priate safety, health, and environmental practices and deter-
hydroxyl and is calculated as follows:
mine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accor-
A 2 B
Basicity, % 5 3100 (1)
dance with internationally recognized principles on standard-
A
ization established in the Decision on Principles for the
where:
Development of International Standards, Guides and Recom-
A = the amount of thiosulfate, as mL of 0.1 N solution
mendations issued by the World Trade Organization Technical
required to titrate the 25 mL aliquot as the specimen in
Barriers to Trade (TBT) Committee.
Test Methods D3898 or D6019,
2. Referenced Documents B = the amount of sodium hydroxide, as mL of 0.1 N
2 solution required to titrate the 25 mL aliquot of the
2.1 ASTM Standards:
specimen in Test Method D3913.
D3898 Test Method for Chromic Oxide in Basic Chromium
Tanning Liquors
6. Precision and Bias
D3913 Test Method forAcidity in Basic Chromium Tanning
6.1 Because basicity is in effect a ratio, the precision
Liquors
indexes are transmitted by the laws governing ratios. If the
D6019 Test Method for Determination of Chromic Oxide in
precision of accuracy of the chromic oxide determination or of
Basic ChromiumTanning Liquors (Ammonium Persulfate
the titratable acidity is expressed in the same relative units; for
Oxidation)
example, percent of value being determined, the precision with
which the basicity is known will be:
3. Significance and Use
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D3897 − 17 D3897 − 18
Standard Practice Test Method for
Calculation of Basicity of Chrome Tanning Liquors
This standard is issued under the fixed designation D3897; 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
1.1 This practice is intended to show how the results of the chromium analysis (Test Methods D3898 or D6019) and the acidity
determination (Test Method D3913) can be combined to permit calculation of the basicity of a chrome tanning liquor.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this 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.
2. Referenced Documents
2.1 ASTM Standards:
D3898 Test Method for Chromic Oxide in Basic Chromium Tanning Liquors
D3913 Test Method for Acidity in Basic Chromium Tanning Liquors
D6019 Test Method for Determination of Chromic Oxide in Basic Chromium Tanning Liquors (Ammonium Persulfate
Oxidation)
3. Significance and Use
3.1 Basicity is a ratio. In any chromic salt solution, the electrovalence of the chromium (+3) is satisfied by the hydroxyl ions
and by acid ions. The extent to which this electravalence is satisfied by the hydroxyl ions, expressed as a percentage, is the basicity.
The basicity of a chrome tanning liquid is closely related to the tanning behavior of the solution.
4. Procedure
4.1 Determine the chromic oxide as described in Test Method D3898 or D6019. Determine the acid as described in Test Method
D3913.
5. Results
5.1 The basicity of the liquor shall be expressed according to the Schorlemmer system. In this system, the basicity is the per
cent of the total chromic oxide that is combined with hydroxyl and is calculated as follows:
A 2 B
Basicity, %5 3100 (1)
A
where:
A = the amount of thiosulfate, as mL of 0.1 N solution required to titrate the 25 mL aliquot as the specimen in Test Methods
D3898 or D6019,
B = the amount of sodium hydroxide, as mL of 0.1 N solution required to titrate the 25 mL aliquot of the specimen in Test
Method D3913.
This practice test method is under the jurisdiction of ASTM Committee D31 on Leather and is the direct responsibility of Subcommittee D31.06 on Chemical Analysis.
Current edition approved Sept. 1, 2017Sept. 1, 2018. Published October 2017October 2018. Originally approved in 1991. Last previous edition approved in 20122017 as
D3897 - 91D3897(2012). -17. DOI: 10.1520/D3897-17.10.1520/D3897-18.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3897 − 18
6. Precision and Bias
6.1 Because basicity is in effect a ratio, the precision indexes are transmitted by the laws governing ratios. If the precision of
accuracy of the chromic oxide determination or of the titratable acidity is expressed in the same relative units; for example, percent
of value being determined, the precision with which the basicity is known will be:
2 2
P 5 P 1P (2)
=
B C A
R
where:
P = precision of acidity in basic chromium tanning liquors,
A
P = precision of chromic oxide in basic chromium tanning liquors,
C
R
P = precision of basicity in basic chromium tanning liquors.
B
6.2 For the reported reproducibility figures for the chromic oxide from Test Method D3898 (δ = 0.90 %) and for acidity from
Test Method D3913 (Procedure I, σ = 1.84 %), δ is given as 2.05 %. This number has the units of basicity. Similarly, repeatability
B
has δ = 0.52 % basicity. Caution should be employed in insisting on extremely close agreements between laboratories or replicates
unless a background of high precision has been established.
7. Keywords
7.1 basicity; chrome tanning liquor; Schorlemmer
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