ASTM D6657-08

Standard Test Method for pH of Wet Blue

SIGNIFICANCE AND USE
This test method is designed to measure the pH of a distilled-water extract of wet blue. This is considered to be a measure of the acidity or alkalinity of the wet blue. Excessive acidity or alkalinity may have a deleterious effect on the aging characteristics of wet blue and the leather made from it.
This test method is suitable for development, control, and service evaluation of wet blue.
SCOPE
1.1 This test method covers the determination of the pH of all types of wet blue and wet white.
1.2 For pH of wet white, the procedure is identical, substitute wet white for wet blue in the standard method.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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-Aug-2008
• ICS: 59.140.10 - Processes and auxiliary materials
• Technical Committee: D31 - Leather
• Drafting Committee: D31.02 - Wet Blue

Relations

• Replaces: ASTM D6657-01(2006) - Standard Test Method for pH of Wet Blue
• Effective Date: 01-Sep-2008
• Replaced By: ASTM D6657-14 - Standard Test Method for pH of Wet Blue
• Effective Date: 01-Apr-2014

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D6657 − 08
StandardTest Method for
1
pH of Wet Blue
This standard is issued under the fixed designation D6657; 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 5. Apparatus
1.1 This test method covers the determination of the pH of 5.1 Electronic pH Meter, with a suitable electrode. The
all types of wet blue and wet white.
meter shall have an accuracy of at least 0.01 pH unit and
reproducibility of 0.05 pH unit.
1.2 For pH of wet white, the procedure is identical, substi-
tute wet white for wet blue in the standard method.
5.2 Analytical Balance, sensitive to 0.01 g or greater.
1.3 The values stated in SI units are to be regarded as
6. Reagents
standard. No other units of measurement are included in this
standard.
6.1 Purity of Water—Unless otherwise indicated, references
to water shall be understood to mean distilled water or water of
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the 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
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- than 0.5 mg, when 100 mL is evaporated and dried in a
platinum dish.
bility of regulatory limitations prior to use.
3
6.2 Commercially Standardized pH Solutions :
2. Referenced Documents
6.2.1 Alkaline Phosphate Buffer Solution (0.01 M trisodium
2
2.1 ASTM Standards:
phosphate, pH = 11.72 at 25 °C)—Dissolve 1.42 g of anhy-
D6659 Practice for Sampling and Preparation of Wet Blue
drous disodium hydrogen phosphate (Na HPO ) in 100 mL of
2 4
for Physical and Chemical Tests
a 0.1 N carbonate-free solution of sodium hydroxide (NaOH)
and dilute to 1 L with water.
3. Terminology
6.2.2 Borax Buffer Solution (0.01 M, pH = 9.18 at 25
3.1 Definitions of Term Specific to this Standard:
°C)—Dissolve 3.81 g of sodium tetraborate decahydrate
3.1.1 The pH of a solution has been defined as the negative
(Na B O · 10H O) in water and dilute to 1 L.
2 4 7 2
logarithm of the hydrogen ion activity. A solution of pH 7 is
6.2.3 Hydrochloric Acid (pH = 1.10 at 25 °C)—Add2gof
neutral at 24 °C. Lower numbers indicate increasing acidity;
concentrated hydrochloric acid (HCl, sp gr 1.19) to 450 g of
higher numbers, increasing alkalinity.
water. Standardize and dilute to 0.1 N.
6.2.4 Phosphate Buffer Solution (0.025 M with respect to
4. Significance and Use
each phosphate, salt pH = 6.86 at 2.5 °C)—Dissolve 3.40 g of
4.1 This test method is designed to measure the pH of a
monobasic potassium phosphate (KH PO ) and 3.55 g of
2 4
distilled-water extract of wet blue. This is considered to be a
anhydrous dibasic sodium phosphate (Na HPO ) in water and
2 4
measure of the acidity or alkalinity of the wet blue. Excessive
dilute to 1 L.
acidity or alkalinity may have a deleterious effect on the aging
6.2.5 Potassium Hydrogen Phthalate Buffer Solution (0.05
characteristics of wet blue and the leather made from it.
M, pH = 4.01 at 25 °C)—Dissolve 10.21 g of potassium
4.2 This test method is suitable for development, control,
hydrogen phthalate (KHC H O ) in water and dilute to 1 L.
8 4 4
and service evaluation of wet blue.
7. Test Specimen
1
This test method is under the jurisdiction ofASTM Committee D31 on Leather
7.1 The specimen shall consist of 10 g, 6 1 g, from a
and is the direct responsibility of Subcommittee D31.02 on Wet Blue.
composite sample prepared according to Practice D6659.
Current edition approved Sept. 1, 2008. Published October 2008. Originally
approved in 2001. Last previous edition approved in 2006 as D6657 - 01(2006).
DOI: 10.1520/D6657-08.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
3
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Commercial buffer salts and solutions prepared in accordance with National
Standards volume information, refer to the standard’s Document Summary page on Bureau of Standards recommendations are sold by reputable laboratory supply
the ASTM website. houses and may be used.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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D6657 − 08
8. Standardization 10. Report
8.1 Use manufacturer’s directions for establishing two point
10.1 Report the following information:
standardization with standard pH solutions that read on either
10.1.1 The pH of the sample shall be reported to the nearest
side of the antici
...

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:D6657–01(Reapproved 2006) Designation:D6657–08
Standard Test Method for
1
pH of Wet Blue
This standard is issued under the fixed designation D 6657; 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
1.1This test method covers the determination of the pH of all types of wet blue.
1.2
1.1 This test method covers the determination of the pH of all types of wet blue and wet white.
1.2 For pH of wet white, the procedure is identical, substitute wet white for wet blue in the standard method.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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.
2. Referenced Documents
2
2.1 ASTM Standards:
D 6659 Practice for Sampling and Preparation of Wet Blue for Physical and Chemical Tests
3. Terminology
3.1 Definitions of Term Specific to this Standard:
3.1.1 The pH of a solution has been defined as the negative logarithm of the hydrogen ion activity.Asolution of pH 7 is neutral
at 24 °C. Lower numbers indicate increasing acidity; higher numbers, increasing alkalinity.
4. Significance and Use
4.1 This test method is designed to measure the pH of a distilled-water extract of wet blue. This is considered to be a measure
of the acidity or alkalinity of the wet blue. Excessive acidity or alkalinity may have a deleterious effect on the aging characteristics
of wet blue and the leather made from it.
4.2 This test method is suitable for development, control, and service evaluation of wet blue.
5. Apparatus
5.1 Electronic pH Meter, with a suitable electrode.The meter shall have an accuracy of at least 0.01 pH unit and reproducibility
of 0.05 pH unit.
5.2 Analytical Balance, sensitive to 0.01 g or greater.
6. Reagents
6.1 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.
3
6.2 Commercially Standardized pH Solutions :
6.2.1 Alkaline Phosphate Buffer Solution (0.01 M trisodium phosphate, pH = 11.72 at 25 °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) and dilute
2 4
to 1 L with water.
1
This test method is under the jurisdiction of ASTM Committee D31 on Leather and is the direct responsibility of Subcommittee D31.02 on Blue Stock.Wet Blue.
Current edition approved Oct.Sept. 1, 2006.2008. Published November 2006.October 2008. Originally approved in 2001. Last previous edition approved in 20012006 as
D 6657 - 01(2006).
2
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM 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
Commercial buffer salts and solutions prepared in accordance with National Bureau of Standards recommendations are sold by reputable laboratory supply houses and
may be used.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1

---------------------- Page: 1 ----------------------
D6657–08
6.2.2 Borax Buffer Solution (0.01 M, pH = 9.18 at 25 °C)—Dissolve 3.81 g of sodium tetraborate decahydrate (Na B O ·
2 4 7
10H O) in water and dilute to 1 L.
2
6.2.3 Hydrochloric Acid (pH = 1.10 at 25 °C)—Add2gof concentrated hydrochloric acid (HCl, sp gr 1.19) to 450 g of water.
Standardize and dilute to 0.1 N.
6.2.4 Phosphate Buffer Solution (0.025 M with respect to each phosphate, salt pH = 6.86 at 2.5 °C)—Dissolve 3.40 g of
monobasic potassium phosphate (KH PO ) and 3.55 g of anhydrous dibasic sodium phosphate (Na HPO ) in water and dilute to
2 4 2 4
1L.
6.2.5 Potassium Hydrogen Phthalate Buffer Solution (0.05 M, pH = 4.01 at 25 °C)—Dissolve 10.21 g of potassium hydrogen
phthalate (KHC H O ) in water and dilute to 1 L.
8
...