ASTM D6410-99(2020)

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: D6410 − 99 (Reapproved 2020)
Standard Test Method for
Determining Acidity of Vegetable Tanning Liquors
This standard is issued under the fixed designation D6410; 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 3.1.1 tannery liquor—water solutions containing vegetable
tannin that are made up and used in a vegetable tannery.
1.1 This test method covers determining the acidity of
tannery liquors made up from vegetable tanning materials.
4. Summary of Test Method
1.2 The values stated in SI units are to be regarded as
4.1 An analytical solution is prepared from the sample of
standard. No other units of measurement are included in this
standard. tannery liquor (Practice D6404). Specimen aliquots from this
analytical solution are then analyzed for total acidity by one of
1.3 This standard does not purport to address all of the
two titrametric methods.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
5. Significance and Use
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
5.1 This test method is used to determine one of the
1.4 This international standard was developed in accor-
chemical properties of tannery liquors which are relevant for
dance with internationally recognized principles on standard-
the vegetable tanning process and influence the astringency of
ization established in the Decision on Principles for the
vegetable tanning liquors. The astringency of liquors is depen-
Development of International Standards, Guides and Recom-
dent upon the solids and tannin content and the acidity. This
mendations issued by the World Trade Organization Technical
test method provides a standard procedure for determining the
Barriers to Trade (TBT) Committee.
total acidity for any sample of vegetable tanning liquor.
5.2 The specimens are aliquots from the analytical solution
2. Referenced Documents
prepared from the sample of tannery liquor collected for this
2.1 ASTM Standards:
purpose.
D4904 Practice for Cooling of Analytical Solutions
D6404 Practice for Sampling Vegetable Materials Contain-
5.3 The total acidity of the liquor sample is determined by
ing Tannin
one of two titrametric procedures described in this test method.
2.2 ALCA Methods:
6. Apparatus and Reagents
A25 Analysis of Tannery Liquors
6.1 Analytical Solution:
3. Terminology
6.1.1 Flask,1Lvolumetric.ClassAflaskswithabulbinthe
3.1 Definitions:
neck (M.C.A. type) are especially suitable for this work.
6.1.2 Hydrometer, preferably with a Barkometer scale (that
is, a scale calibrated in °Bk).The three digits to the right of the
This test method is under the jurisdiction ofASTM Committee D31 on Leather decimal point on a standard specific gravity reading are equal
and is the direct responsibility of Subcommittee D31.01 on Vegetable Leather. This
to the Barkometer scale reading. That is, a sp.gr. of 1.200
test method has been adapted from and is a replacement for the acidity determina-
equals 200°Bk and a sp.gr. of 1.020 equals 20°Bk.
tion portion of Method A25 of the Official Methods of the American Leather
Chemists Association.
6.2 Acidity Determination—Method I:
Current edition approved Dec. 1, 2020. Published December 2020. Originally
approved in 1999. Last previous edition approved in 2014 as D6410 – 99 (2014).
6.2.1 Graduated Cylinder, glass-stoppered, graduated to
DOI: 10.1520/D6410-99R20.
contain 250 mL.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
6.2.2 Gelatin Solution, 1 %, neutral to bromocresol purple.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
The addition of 25 mL of 95 % ethyl alcohol per litre is
the ASTM website.
recommended to prevent frothing. The solution shall be ad-
Official Methods of the American Leather Chemists Association. Available
justed to neutrality to bromocresol purple with 0.1 N acetic
from the American Leather Chemists Association, University of Cincinnati, P.O.
Box 210014, Cincinnati, OH 45221-0014. acid or 0.1 N sodium hydroxide.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6410 − 99 (2020)
6.2.3 Kaolin , acid-washed kaolin clay which conforms to 8.2.1.1 Transfera25mLaliquotoftheanalyticalsolutionto
the following specifications: a 250 mL graduated and stoppered cylinder. Then add 50 mL
6.2.3.1 Suspend 1.0 g kaolin in 100 mL distilled water. The of the gelatin solution to the cylinder. Dilute this mixture to
pH value should be between 4.5 and 6.0 after 5 min. 250 mL with distilled water. Then add 15 g of kaolin, the
6.2.3.2 Amixture of 2.0 g kaolin and 200 mLdistilled water stopper cylinder, and shake vigorously.Then allow the mixture
are shaken for 10 min and the mixture filtered through the to settle for at least 15 m
...