ASTM D2810-72(1996)

Standard Test Method for pH 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.
1.2 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.

General Information

• Status: Historical
• Publication Date: 31-Dec-1995
• ICS: 59.140.30 - Leather and furs
• Technical Committee: D31 - Leather
• Drafting Committee: D31.06 - Chemical Analysis

Relations

• Replaced By: ASTM D2810-01 - Standard Test Method for pH of Leather
• Effective Date: 10-May-2001

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 2810 – 72 (Reapproved 1996)
Standard Test Method for
pH of Leather
This standard is issued under the fixed designation D 2810; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 5. Apparatus
1.1 This test method covers the determination of the pH of 5.1 Electrometric pH Meter, either battery or line-operated,
all types of leather. with a glass electrode and calomel reference electrode. The
1.2 This standard does not purport to address all of the meter shall have a maximum scale division of 0.1 pH unit, and
safety concerns, if any, associated with its use. It is the shall have an accuracy of at least 0.1 pH unit and reproduc-
responsibility of the user of this standard to establish appro- ibility of 0.05 pH unit.
priate safety and health practices and determine the applica-
NOTE 1—Sellers list reasonably priced models having an accuracy of
bility of regulatory limitations prior to use.
60.05, sensitive to 0.02 and with reproducibility to 0.02 pH units.
5.2 Analytical Balance, sensitive to 0.01 g.
2. Terminology
2.1 Definition of Term Specific to this Standard:
6. Reagents
2.1.1 The pH of a solution has been defined as the negative
6.1 Purity of Reagents—Reagent grade chemicals shall be
logarithm of the hydrogen ion activity. A solution of pH 7 is
used in all tests. Unless otherwise indicated, it is intended that
neutral at 24°C. Lower numbers indicate increasing acidity;
all reagents shall conform to the specifications of the Commit-
higher numbers, increasing alkalinity.
tee on Analytical Reagents of the American Chemical Society,
where such specifications are available. Other grades may be
3. Significance and Use
used, provided it is first ascertained that the reagent is of
3.1 This test method is designed to measure the pH of a
sufficiently high purity to permit its use without lessening the
distilled-water extract of leather. This is considered to be a
accuracy of the determination.
measure of the acidity or alkalinity of the leather. Excessive
6.2 Purity of Water—Unless otherwise indicated, references
acidity or alkalinity may have a deleterious effect on the aging
to water shall be understood to mean distilled water or water of
characteristics of leather.
equal purity. Distilled water shall have a pH value of not less
3.2 This test method is suitable for development, control,
than 5.5 nor more than 7.0 and shall give a residue of not more
and service evaluation of leather.
than 0.5 mg, when 100 mL is evaporated and dried in a
platinum dish.
4. Interferences
6.3 Standard pH Solutions:
4.1 If the leather contains an excessive amount of fats or
6.3.1 Alkaline Phosphate Buffer Solution (0.01 M trisodium
greases or has been treated with a material to obtain water
phosphate, pH 5 11.72 at 25°C)—Dissolve 1.42 g of anhy-
repellency, the wettability and consequently the extractability
drous disodium hydrogen phosphate (Na HPO ) in 100 mL of
2 4
may be affected.
a 0.1 N carbonate-free solution of sodium hydroxide (NaOH)
4.2 If the specimen is difficult or impossible to wet, it may
and dilute to 1 L with water.
be treated by any of the following procedures:
6.3.2 Borax Buffer Solution (0.01 M, pH 5 9.18 at 25°C)—
4.2.1 A vacuum may be used to effect wetting.
Dissolve 3.81 g of sodium tetraborate decahydrate (Na B O ·
2 4 7
4.2.2 Mix with the required amount of water for 1 min in a
2 10 H O) in water and dilute to 1 L.
disintegrator.
6.3.3 Hydrochloric Acid (pH 5 1.10 at 25°C)—Add2gof
4.2.3 Extract the weighed specimen with a fat solvent in a
concentrated hydrochloric acid (HCl, sp gr 1.19) to 450 g of
Soxhlet apparatus for 5 h. Allow the specimen to air until all
solvent has evaporated; then proceed as outlined in Section 9.
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
This test method is under the jurisdiction of ASTM Committee D-31 on Leather listed by the American Chemical Society, see Analar Standards for Laboratory
and is the direct responsibility of Subcommittee D31.06.01 on General Methods. Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
This test method was developed in cooperation with the American Leather Chemists and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,
Assn. (Standard Method B 20 – 1969). MD.
Current edition approved April 3, 1972. Published October 1972. Originally Buffer salts and solutions prepared in accordance with National Bureau of
published as D 2810 – 69 T. Last previous edition D 2810 – 69 T. Standards recommendations are sold by reputable laboratory supply houses and may
A Waring Blender has been found satisfactory. be used.
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