ASTM D5356-17a

Standard Test Method for pH of Chrome Tanning Solutions

SIGNIFICANCE AND USE
5.1 This test method is designed to measure the pH of a chrome tanning solution which has been diluted to a specific concentration. This is considered to be a measure of the acidity or alkalinity of the solution.  
5.2 This test method is suitable for quality control in the manufacture of leather.
SCOPE
1.1 This test method covers the determination of the pH of chrome tanning solutions.  
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-2017
• ICS: 59.140.40 - Machines and equipment for leather and fur production
• Technical Committee: D31 - Leather
• Drafting Committee: D31.06 - Chemical Analysis

Relations

• Replaces: ASTM D5356-17 - Standard Test Method for pH of Chrome Tanning Solutions
• Effective Date: 01-Sep-2017
• Refers: ASTM D3898-93(2015) - Standard Test Method for Chromic Oxide in Basic Chromium Tanning Liquors
• Effective Date: 01-Sep-2015

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: D5356 − 17a
Standard Test Method for
1
pH of Chrome Tanning Solutions
This standard is issued under the fixed designation D5356; 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 4. Summary of Test Method
1.1 This test method covers the determination of the pH of 4.1 The chrome tanning liquor is diluted to a concentration
chrome tanning solutions. of 25.0 6 0.5 g chromic oxide equivalent per litre, allowed to
come to equilibrium and the pH is then measured with the
1.2 The values stated in SI units are to be regarded as
appropriate meter.
standard. No other units of measurement are included in this
standard.
5. Significance and Use
1.3 This standard does not purport to address all of the
5.1 This test method is designed to measure the pH of a
safety concerns, if any, associated with its use. It is the
chrome tanning solution which has been diluted to a specific
responsibility of the user of this standard to establish appro-
concentration.This is considered to be a measure of the acidity
priate safety, health, and environmental practices and deter-
or alkalinity of the solution.
mine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accor- 5.2 This test method is suitable for quality control in the
manufacture of leather.
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
6. Apparatus
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
6.1 Electronic pH Meter, with a suitable electrode. The
Barriers to Trade (TBT) Committee.
meter shall have an accuracy of at least 0.1 pH unit and
reproducibility of 0.05 pH unit.
2. Referenced Documents
2
7. Reagents
2.1 ASTM Standards:
D3898 Test Method for Chromic Oxide in Basic Chromium
7.1 Purity of Reagents—Reagent grade chemicals shall be
Tanning Liquors
used in all tests. Unless otherwise indicated, it is intended that
all reagents shall conform to the specifications of the Commit-
3. Terminology
tee onAnalytical Reagents of theAmerican Chemical Society,
3
3.1 Definitions of Terms Specific to This Standard: where such specifications are available. Other grades may be
3.1.1 pH, of a solution—the negative logarithm of the used, provided it is first ascertained that the reagent is of
hydrogen ion activity. sufficiently high purity to permit its use without lessening the
3.1.1.1 Discussion—A solution of pH 7 is neutral at 24 °C. accuracy of the determination.
Lower numbers indicate increasing acidity, higher numbers
7.2 Purity of Water—Unless otherwise indicated, references
indicate increasing alkalinity.
to water shall be understood to mean distilled water, deionized
water, or water of equal purity. Distilled water shall have a pH
value of not less than 5.5 nor more than 7.0 and shall give a
1
This test method is under the jurisdiction ofASTM Committee D31 on Leather
and is the direct responsibility of Subcommittee D31.06 on Chemical Analysis
Current edition approved Sept. 1, 2017. Published October 2017. Originally
3
approved in 1993. Last previous edition approved in 2017 as D5356 – 17. DOI: Reagent Chemicals, American Chemical Society Specifications , American
10.1520/D5356-17A. Chemical Society, Washington, DC. For suggestions on the testing of reagents not
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or listed by the American Chemical Society, see Analar Standards for Laboratory
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Standards volume information, refer to the standard’s Document Summary page on and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,
the ASTM website. MD.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D5356 − 17a
cylinder or weighed quantity shall be transferred to a 100-mL volumetric
residue of not more than 0.5 mg when 100 mL is evaporated
flask. Diluting with water at room temperature will give sufficiently
and dried in a platinum dish.
accurate dilution. Spent chrome tanning liquor does not require dilution.
4
7.3 Commercially Standardized pH Solutions:
NOTE 2—If the dilution described in Note 1 ta
...

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: D5356 − 17 D5356 − 17a
Standard Test Method for
1
pH of Chrome Tanning Solutions
This standard is issued under the fixed designation D5356; 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 test method covers the determination of the pH of chrome tanning solutions.
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 safety, health, and healthenvironmental 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
2.1 ASTM Standards:
D3898 Test Method for Chromic Oxide in Basic Chromium Tanning Liquors
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 pH, of a solution—the negative logarithm of the hydrogen ion activity.
1
This 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 May 15, 2017Sept. 1, 2017. Published May 2017October 2017. Originally approved in 1993. Last previous edition approved in 20152017 as
D5356 – 10D5356 – 17.(2015). DOI: 10.1520/D5356-17.10.1520/D5356-17A.
2
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.
3.1.1.1 Discussion—
A solution of pH 7 is neutral at 24 °C. Lower numbers indicate increasing acidity, higher numbers indicate increasing alkalinity.
4. Summary of Test Method
4.1 The chrome tanning liquor is diluted to a concentration of 25.0 6 0.5 g chromic oxide equivalent per litre, allowed to come
to equilibrium and the pH is then measured with the appropriate meter.
5. Significance and Use
5.1 This test method is designed to measure the pH of a chrome tanning solution which has been diluted to a specific
concentration. This is considered to be a measure of the acidity or alkalinity of the solution.
5.2 This test method is suitable for quality control in the manufacture of leather.
6. Apparatus
6.1 Electronic pH Meter, either battery or line-operated equipped with appropriate electrodes. with a suitable electrode. The
meter shall have a maximum scale division ofan accuracy of at least 0.1 pH unit and reproducibility of 0.05 pH unit.
7. Reagents
7.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D5356 − 17a
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such specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high
purity to permit its use without lessening the accuracy of the determination.
7.2 Purity of Water—Unless otherwise indicated, references to water shall be understood to mean distilled water, deionized
water, or water of equal purity. Distilled water shall have a pH value of not less than 5.5 nor more than 7.0 and shall give a residue
of not more than 0.5 mg when 100 mL is evaporated and dried in a platinum dish.
4
7.3 Buffer Solutions—Commercially Standardized pH Solutions: Commerciallyavailable buffer solutions of 2.00 6 0.02 pH
and 4.00 6 0.02 pH shall be used for meter standardization, in accordance with the manufacturer’s recommendations.
7.3.1 Hydrochloric Acid (pH = 1.10 at 25 °C)—Add 2 g of concentrated hydrochloric acid (HCl, sp gr 1.10) to 450 g of water.
Standardize and dilute to 0.1 N.
7.3.2 Potass
...