ASTM D4370-84(1994)

Standard Test Methods for Acid and Base Milliequivalent Content of Electrocoat Bath

SCOPE
1.1 These test methods cover the determination of acid and base milliequivalent contents of anodic and cathodic electrocoat baths and their ultrafiltrates.  
1.2 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of whoever uses this standard to consult and establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 09-Jan-2001
• ICS: 25.220.40 - Metallic coatings
• Technical Committee: D01 - Paint and Related Coatings, Materials, and Applications
• Drafting Committee: D01.21 - Chemical Analysis of Paints and Paint Materials

Relations

• Replaced By: ASTM D4370-01 - Standard Test Methods for Acid and Base Milliequivalent Content of Electrocoat Bath
• Effective Date: 10-Jan-2001
• Referred By: ASTM D1978-91(2018) - Standard Guide for Analysis of Electrocoat Bath Samples
• Effective Date: 10-Jan-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NOTICE: This standard has either been superseded and replaced by a new version or discontinued.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 4370 – 84 (Reapproved 1994)
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Methods for
Acid and Base Milliequivalent Content of Electrocoat Bath
This standard is issued under the fixed designation D 4370; 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 6. Reagents
1.1 These test methods cover the determination of acid and 6.1 Purity of Reagents—Reagent grade chemicals shall be
base milliequivalent contents of anodic and cathodic electro- used in all tests. Unless otherwise indicated, it is intended that
coat baths and their ultrafiltrates. all reagents shall conform to the specifications of the Commit-
1.2 This standard does not purport to address all of the tee on Analytical Reagents of the American Chemical Society,
safety concerns, if any, associated with its use. It is the where such specifications are available.
responsibility of the user of this standard to establish appro- Other grades may be used, provided it is ascertained that the
priate safety and health practices and determine the applica- reagent is of sufficiently high purity to permit its use without
bility of regulatory limitations prior to use. lessening the accuracy of the determination.
6.2 Purity of Water—References to water shall be under-
2. Referenced Documents
stood to mean water conforming to Type II of Specification
2.1 ASTM Standards:
D 1193.
D 1193 Specification For Reagent Water 6.3 Potassium Hydroxide Solution in Methanol, 0.1
N—Prepare by dissolving 5.6 g of potassium hydroxide (KOH)
3. Summary of Test Methods
pellets in 1 L of methanol. Standardize against NIST standard
3.1 Specimens are titrated with standard acid and alkali
reference material of acid potassium phthalate No. 84 using an
solutions respectively. Alternative procedures are given for
automatic potentiometric titrator to a given end point or,
determining acid and base concentrations potentiometrically or
alternatively, to a phenolphthalein end point.
using a pH meter.
6.4 Hydrochloric Acid Solution, 0.1 N—Prepare by mixing
about 8.50 mL of concentrated hydrochloric acid (HCl) (1.19
4. Significance and Use
sp gr) into a mixture of 600 mL water and 400 mL methanol.
4.1 The acid and base concentrations are a measurement of
Standardize against 0.1 N potassium hydroxide solution (see
the titratable acidic and alkaline components in the electrocoat
6.3).
baths. These measurements are used for research, production or
6.5 1,3-Propanediol (Propylene Glycol) (PG).
electrocoat bath process control.
6.6 Tetrahydrofuran (THF).
6.7 Reference pH Standard Solutions—Commercial stan-
5. Apparatus
dards of pH 4.0, 7.0, and 10.0.
5.1 Automatic Potentiometric Titrator with Stirrer and Re-
7. Sampling and Sample Preparation
corder, any model.
5.2 Analytical Balance, with sensitivity of 0.1 mg.
7.1 The sample should be obtained while the electrocoat
5.3 pH Meter, any model.
bath is under proper circulation such that a uniform material is
5.4 Glass and Saturated Calomel Electrodes.
obtained. In case of an ultrafiltrate, the material should be
5.5 Syringes, 5-mL disposable.
thoroughly mixed or stirred prior to sampling to assure
uniformity.
7.2 After sampling and prior to removing a test specimen, it
is mandatory that the samples be shaken or stirred until they are
homogeneous and free of any settled material. This is particu-
These test methods are under the jurisdiction of ASTM Committee D-1 on Paint
larly important if there is a delay between sampling the bath
and Related Coatings, Materials, and Applications and are the direct responsibility
of Subcommittee D01.21 on Chemical Analysis of Paint and Paint Materials. and performing the test. The absence of settled material can be
Current edition approved June 28, 1984. Published November 1984.
ascertained visually (in a transparent container) or by inserting
Annual Book of ASTM Standards, Vol 11.01.
a spatula, scraping the bottom of the container, and making
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not sure that there is no settled matter. The shaking or stirring of
listed by the American Chemical Society, see Analar Standards for Laboratory
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,
MD. Svehla, G., Automatic Potentiometric Titration, Pergamon Press, 1978, p. 187.
D 4370
the samples should be carried out up to the moment of taking
a specimen; this Point is Very Important.
8. Base Concentration Content
8.1 Stir the sample very thoroughly to disperse materials
that might have settled to the bottom of the container. With the
aid of a syringe, withdraw approximately 5 mL of the sample
quickly, weigh the full syringe to 0.1 mg, and record this
weight as W . Transfer the entire contents of the syringe into a
100-mL beaker. Reweigh the empty syringe to 0.1 mg and
record as W . Duplicate the procedure using a second speci-
men.
8.2 Add approximately 40 mL of THF/PG 80/20 mixture to
the specimens in the beakers a
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