ASTM D6657-01

Standard Test Method for pH of Wet Blue

SCOPE
1.1 This test method covers the determination of the pH of all types of 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: 09-May-2001
• ICS: 59.140.10 - Processes and auxiliary materials
• Technical Committee: D31 - Leather
• Drafting Committee: D31.02 - Wet Blue

Relations

• Replaced By: ASTM D6657-01(2006) - Standard Test Method for pH of Wet Blue
• Effective Date: 01-Oct-2006

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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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:D6657–01
Standard Test Method for
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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 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
1.1 This test method covers the determination of the pH of
than 0.5 mg, when 100 mL is evaporated and dried in a
all types of wet blue.
platinum dish.
1.2 This standard does not purport to address all of the
6.2 Commercially Standardized pH Solutions :
safety concerns, if any, associated with its use. It is the
6.2.1 Alkaline Phosphate Buffer Solution (0.01 M trisodium
responsibility of the user of this standard to establish appro-
phosphate, pH = 11.72 at 25 °C)—Dissolve 1.42 g of anhy-
priate safety and health practices and determine the applica-
drous disodium hydrogen phosphate (Na HPO ) in 100 mL of
bility of regulatory limitations prior to use. 2 4
a 0.1 N carbonate-free solution of sodium hydroxide (NaOH)
2. Referenced Documents and dilute to 1 L with water.
6.2.2 Borax Buffer Solution (0.01 M, pH = 9.18 at 25
2.1 ASTM Standards:
°C)—Dissolve 3.81 g of sodium tetraborate decahydrate
D 6659 Practice for Sampling and Preparation of Wet Blue
(Na B O · 10H O) in water and dilute to 1 L.
for Physical and Chemical Tests 2 4 7 2
6.2.3 Hydrochloric Acid (pH = 1.10 at 25 °C)—Add2gof
3. Terminology
concentrated hydrochloric acid (HCl, sp gr 1.19) to 450 g of
water. Standardize and dilute to 0.1 N.
3.1 Definitions of Term Specific to this Standard:
6.2.4 Phosphate Buffer Solution (0.025 M with respect to
3.1.1 The pH of a solution has been defined as the negative
each phosphate, salt pH = 6.86 at 2.5 °C)—Dissolve 3.40 g of
logarithm of the hydrogen ion activity. A solution of pH 7 is
monobasic potassium phosphate (KH PO ) and 3.55 g of
neutral at 24 °C. Lower numbers indicate increasing acidity; 2 4
anhydrous dibasic sodium phosphate (Na HPO ) in water and
higher numbers, increasing alkalinity. 2 4
dilute to 1 L.
4. Significance and Use
6.2.5 Potassium Hydrogen Phthalate Buffer Solution (0.05
M, pH = 4.01 at 25 °C)—Dissolve 10.21 g of potassium
4.1 This test method is designed to measure the pH of a
hydrogen phthalate (KHC H O ) in water and dilute to 1 L.
distilled-water extract of wet blue. This is considered to be a
8 4 4
measure of the acidity or alkalinity of the wet blue. Excessive
7. Test Specimen
acidity or alkalinity may have a deleterious effect on the aging
7.1 The specimen shall consist of 10 g, 6 1 g, from a
characteristics of wet blue and the leather made from it.
composite sample prepared according to Practice D 6659.
4.2 This test method is suitable for development, control,
and service evaluation of wet blue.
8. Standardization
5. Apparatus
8.1 Use manufacturer’s directions for establishing two point
standardization with standard pH solutions that read on either
5.1 Electronic pH Meter, with a suitable electrode. The
side of the anticipated pH of the solution to be tested. Wash
meter shall have an accuracy of at least 0.01 pH unit and
electrodes by immersing in three changes of water and estab-
reproducibility of 0.05 pH unit.
lish a fresh liquid junction after blotting electrodes if using
5.2 Analytical Balance, sensitive to 0.01 g or greater.
sleeve type electrode prior to testing each solution.
6. Reagents
8.2 Check for electrode drift with either of the buffers and
restandardize if necessary.
6.1 Purity of Water—Unless otherwise indicated, reference
...