ASTM D5356-17
(Test Method)Standard Test Method for pH of Chrome Tanning Solutions
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 and health 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.
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Designation: D5356 − 17
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 and health practices and determine the applica-
or alkalinity of the solution.
bility 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 pH Meter, either battery or line-operated equipped with
Barriers to Trade (TBT) Committee.
appropriate electrodes. The meter shall have a maximum scale
division of 0.1 pH unit and reproducibility of 0.05 pH unit.
2. Referenced Documents
2
2.1 ASTM Standards:
7. Reagents
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,
3.1 Definitions of Terms Specific to This Standard: 3
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.
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 May 15, 2017. Published May 2017. Originally
3
approved in 1993. Last previous edition approved in 2015 as D5356 – 10(2015). Reagent Chemicals, American Chemical Society Specifications , American
DOI: 10.1520/D5356-17. 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 service@astm.org. 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 − 17
cylinder or weighed quantity shall be transferred to a 100-mL volumetric
7.3 Buffer Solutions—Commercially available buffer solu-
flask. Diluting with water at room temperature will give sufficiently
tions of 2.00 6 0.02 pH and 4.00 6 0.02 pH shall be used for
accurate dilution. Spent chrome tanning liquor does not require dilution.
meter standardization, in accordance with the manufacturer’s
NOTE 2—If the dilution described in Note 1 takes place essentially at
recommendations.
room temperature, the change in pH is sufficiently slight that 60-min
equilibration will suffice. If the pH is measured before 60 min has elapsed,
...
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 − 10 (Reapproved 2015) D5356 − 17
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 and health 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
E70 Test Method for pH of Aqueous Solutions With the Glass Electrode
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 Dec. 1, 2015May 15, 2017. Published December 2015May 2017. Originally approved in 1993. Last previous edition approved in 20102015 as
D5356 – 10.D5356 – 10(2015). DOI: 10.1520/D5356-10R15.10.1520/D5356-17.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. 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. 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. For general details of a procedure, Test Method E70 should
be consulted. The provisions of the standard shall be governing except where the text of this test method specifically deviates.
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 pH Meter, either battery or line-operated equipped with appropriate electrodes. The meter shall have a maximum scale
division of 0.1 pH unit and reproducibility of 0.05 pH unit.
NOTE 1—Sellers list reasonably priced models having more sensitivity and greater reproducibility.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D5356 − 17
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
3
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 water,
deionized water, or water of equal purity.
7.3 Buffer Solutions—Commercially available 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 and the provisions set forth in Test Method
recommendations.E70.
8. Standardization
8.1 Standardize
...
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