ASTM D2810-18

Standard Test Method for pH of Leather

SIGNIFICANCE AND USE
4.1 This test method is designed to measure the pH of a distilled water extract of leather. This is considered to be a measure of the acidity or alkalinity of the leather. Excessive acidity or alkalinity may have a deleterious effect on the aging characteristics of leather.  
4.2 This test method is suitable for development, control, and service evaluation of leather.
SCOPE
1.1 This test method covers the determination of the pH of all types of leather. This method does not apply to wet blue or wet white.  
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: 59.140.30 - Leather and furs
• Technical Committee: D31 - Leather
• Drafting Committee: D31.06 - Chemical Analysis

Relations

• Replaces: ASTM D2810-13 - Standard Test Method for pH of Leather
• Effective Date: 01-Sep-2018
• Refers: ASTM D2813-03(2008) - Standard Practice for Sampling Leather for Physical and Chemical Tests
• Effective Date: 01-Sep-2008
• Refers: ASTM D2813-03 - Standard Practice for Sampling Leather for Physical and Chemical Tests
• Effective Date: 01-Oct-2003
• Refers: ASTM D2813-97 - Standard Practice for Sampling Leather for Physical and Chemical Tests
• Effective Date: 10-Apr-1997

Overview

ASTM D2810-18, Standard Test Method for pH of Leather, is an internationally recognized method established by ASTM International for determining the pH of leather samples. This standard is essential in assessing the acidity or alkalinity of various leather types, except wet blue or wet white leather. The pH measurement provides a key indicator of leather quality, durability, and suitability for various applications. High or low pH values can adversely affect the aging process and service life of leather, making regular testing vital in quality control, product development, and performance evaluation.

Key Topics

• pH Determination: The test method outlines procedures for extracting and measuring the pH of leather using distilled water, an electronic pH meter, and analytical best practices.
• Acidity and Alkalinity: pH is a crucial chemical characteristic; excessive acidity or alkalinity can result in degradation, affecting appearance, flexibility, and mechanical properties.
• Applicable Leathers: The method applies to finished, crust, and all types of leather except "wet blue" and "wet white" (pre-tanned hides).
• Sampling and Precision: The standard references ASTM D2813 for leather sampling to ensure representativeness and reproducibility of results.
• Interferences: Special notes are provided regarding leather with high fat content or water repellent treatments that could impact extractability and measurement accuracy.
• Reporting Requirements: Results must be reported accurately, specifying individual or average values and including any pH differential (delta pH), offering detailed transparency on sample characteristics.

Applications

Proper pH measurement of leather is vital in multiple scenarios across the leather industry:

• Product Development: Ensuring appropriate pH levels helps manufacturers produce leather with desirable characteristics for end-use, minimizing risk of premature aging.
• Quality Control: Regular pH testing helps manufacturers, suppliers, and tanneries maintain consistency in production and comply with industry requirements.
• Service Evaluation: Product performance-particularly in items subject to wear and environmental exposure, such as footwear, upholstery, and accessories-can be predicted or assured through effective pH assessment.
• Specification Compliance: Meeting the pH requirements is often a prerequisite in regulated markets and for certain clients, particularly those specifying durability and environmental safety.
• Troubleshooting: Identifying the cause of product failures such as brittleness or discoloration often starts with a pH assessment per ASTM D2810-18.

Related Standards

Several related ASTM standards support and complement the procedures outlined in ASTM D2810-18:

• ASTM D2813: Practice for Sampling Leather for Physical and Chemical Tests, cited for creating composite samples representative of entire batches.
• Other ASTM Leather Standards: For those assessing leather quality, additional standards address factors like physical properties, chemical content, and performance.
• International Principles: This standard aligns with the WTO Technical Barriers to Trade (TBT) Committee principles, fostering harmonization and global applicability in leather testing.

Keywords: pH of leather, leather testing standards, ASTM D2810-18, acidity, alkalinity, leather quality control, delta pH, leather durability, pH measurement, leather manufacturing standards.

By establishing a consistent, reproducible method for measuring leather pH, ASTM D2810-18 supports manufacturers, testing laboratories, and end-users in ensuring leather products retain their quality and performance throughout their lifecycle.

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: D2810 − 18
Standard Test Method for
pH of Leather
This standard is issued under the fixed designation D2810; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope 4. Significance and Use
1.1 This test method covers the determination of the pH of
4.1 This test method is designed to measure the pH of a
all types of leather. This method does not apply to wet blue or
distilled water extract of leather. This is considered to be a
wet white.
measure of the acidity or alkalinity of the leather. Excessive
acidity or alkalinity may have a deleterious effect on the aging
1.2 The values stated in SI units are to be regarded as
characteristics of leather.
standard. No other units of measurement are included in this
standard.
4.2 This test method is suitable for development, control,
and service evaluation of leather.
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 appro- 5. Interferences
priate safety, health, and environmental practices and deter-
5.1 If the leather contains an excessive amount of fats or
mine the applicability of regulatory limitations prior to use.
greases or has been treated with a material to obtain water
1.4 This international standard was developed in accor-
repellency, the wettability and consequently the extractability
dance with internationally recognized principles on standard-
may be affected.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
5.2 If the specimen is difficult or impossible to wet, it may
mendations issued by the World Trade Organization Technical
be treated by any of the following procedures:
Barriers to Trade (TBT) Committee.
5.2.1 A vacuum may be used to effect wetting.
5.2.2 Mix with the required amount of water for 1 min in a
2. Referenced Documents
disintegrator.
2.1 ASTM Standards:
5.2.3 Extract the weighed specimen with a fat solvent in a
D2813 Practice for Sampling Leather for Physical and
Soxhlet apparatus for 5 h. Allow the specimen to air until all
Chemical Tests
solvent has evaporated; then proceed as outlined in Section 10.
3. Terminology
6. Apparatus
3.1 Definitions of Terms Specific to This Standard:
6.1 Electronic pH Meter, with a suitable electrode. The
3.1.1 The pH of a solution has been defined as the negative
meter shall have an accuracy of at least 0.01 pH unit, and
logarithm of the hydrogen ion activity. A solution of pH 7 is
reproducibility of 0.05 pH unit.
neutral at 24°C. Lower numbers indicate increasing acidity;
higher numbers, increasing alkalinity.
6.2 Analytical Balance, sensitive to 0.01 g or greater.
3.1.2 The pH difference figure (delta pH) is the difference
between the pH of a solution and its ten-fold dilution. 7. Reagents
7.1 Purity of Reagents—Reagent grade chemicals shall be
used in all tests. Unless otherwise indicated, it is intended that
This test method is under the jurisdiction ofASTM Committee D31 on Leather
all reagents shall conform to the specifications of the Commit-
and is the direct responsibility of Subcommittee D31.06 on ChemicalAnalysis.This
tee onAnalytical Reagents of theAmerican Chemical Society,
test method was developed in cooperation with the American Leather Chemists
Assn. (Standard Method B20 – 1969).
Current edition approved Sept. 1, 2018. Published September 2018. Originally
approved in 1969. Last previous edition approved in 2013 as D2810 – 13. DOI:
10.1520/D2810-18. A Waring Blender has been found satisfactory.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2810 − 18
where such specifications are available. Other grades may be standard pH solutions that read on either side of the anticipated
used, provided it is first ascertained that the reagent is of pH of the solution to be tested.
sufficiently high purity to permit its use without lessening the
9.3 Check for electrode drift with either of the buffers and
accuracy of the determination.
restandardize if necessary.
7.2 Purity of Water—Unless otherwise indicated, references
10. Procedure
to water shall be understood to mean distilled water or water of
10.1 Weigh the specimen in duplicate to the nearest 0.1 g
equal purity. Distilled water shall have a pH value of not less
and transfer to 250-mL Erlenmeyer flasks. Add water in the
than 5.5 nor more than 7.0 and shall give a residue of not more
amount of twenty times the mass of the specimen. Stopper the
than 0.5 mg, when 100 mL is evaporated and dried in a
flasks and agitate thoroughly. Let stand at the Standard
platinum dish.
Laboratory Temperature, 23.0 6 1 °C (73.4 6 1.8 °F), with
7.3 Commercially Standardized pH Solutions:
occasional agitation for not less than 4 nor more than 18 h.
7.3.1 Alkaline Phosphate Buffer Solution (0.01 M trisodium
Agitate thoroughly and transfer to a clean beaker
...

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: D2810 − 13 D2810 − 18
Standard Test Method for
pH of Leather
This standard is issued under the fixed designation D2810; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope
1.1 This test method covers the determination of the pH of all types of leather. This method does not apply to wet blue.blue
or wet white.
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
2.1 ASTM Standards:
D2813 Practice for Sampling Leather for Physical and Chemical Tests
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 The pH of a solution has been defined as the negative logarithm of the hydrogen ion activity. A solution of pH 7 is neutral
at 24°C. Lower numbers indicate increasing acidity; higher numbers, increasing alkalinity.
3.1.2 The pH difference figure (delta pH) is the difference between the pH of a solution and its ten-fold dilution.
4. Significance and Use
4.1 This test method is designed to measure the pH of a distilled-water distilled water extract of leather. This is considered to
be a measure of the acidity or alkalinity of the leather. Excessive acidity or alkalinity may have a deleterious effect on the aging
characteristics of leather.
4.2 This test method is suitable for development, control, and service evaluation of leather.
5. Interferences
5.1 If the leather contains an excessive amount of fats or greases or has been treated with a material to obtain water repellency,
the wettability and consequently the extractability may be affected.
5.2 If the specimen is difficult or impossible to wet, it may be treated by any of the following procedures:
5.2.1 A vacuum may be used to effect wetting.
5.2.2 Mix with the required amount of water for 1 min in a disintegrator.
5.2.3 Extract the weighed specimen with a fat solvent in a Soxhlet apparatus for 5 h. Allow the specimen to air until all solvent
has evaporated; then proceed as outlined in Section 10.
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. This test
method was developed in cooperation with the American Leather Chemists Assn. (Standard Method B20 – 1969).
Current edition approved May 1, 2013Sept. 1, 2018. Published May 2013September 2018. Originally approved in 1969. Last previous edition approved in 20072013 as
D2810 – 07.D2810 – 13. DOI: 10.1520/D2810-13.10.1520/D2810-18.
A Waring Blender has been found satisfactory.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2810 − 18
6. Apparatus
6.1 Electronic pH Meter, either battery or line-operated with a suitable electrode. The meter shall have a resolution of 0.1/0.01
an accuracy of at least 0.01 pH unit, and shall have a relative accuracy of 60.1/0.01reproducibility of 0.05 pH unit.
6.2 Analytical Balance, sensitive to 0.01 g.g or greater.
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
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 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.
7.3 Standard Commercially Standardized pH Solutions:
7.3.1 Alkaline Phosphate Buffer Solution (0.01 M trisodium phosphate, pH = 11.72 at 25°C25 °C)—Dissolve 1.42 g of
anhydrous disodium hydrogen phosphate (Na HPO ) in 100 mL of a 0.1 N carbonate-free solution of sodium hydroxide (NaOH)
2 4
and dilute to 1 L with water.
7.3.2 Borax Buffer Solution (0.01 M, pH = 9.18 at 25°C)—25 °C)—Dissolve 3.81 g of sodium tetraborate decahydrate
(Na B O · 10 H O) in water and dilute to 1 L.
2 4 7 2
7.3.3 Hydrochloric Acid (pH = 1.10 at 25°C25 °C)—Add 2 g of concentrated hydrochloric acid (HCl, sp gr 1.19) to 450 g of
water.
...