ASTM D6405-99
(Practice)Standard Practice for Extraction of Tannins from Raw and Spent Materials
Standard Practice for Extraction of Tannins from Raw and Spent Materials
SCOPE
1.1 This practice covers extracting the tannin from raw and spent materials. The water extract obtained by this method is used to determine the tannin content of the original material. Analysis for total solids, soluble solids, and soluble non-tannins of the water extract from a material provides the information necessary to calculate the extractable tannin content of that material. The types of materials typically analyzed by this practice are products of plants such as woods, barks, leaves, nuts, fruits, roots, etc. and any of a wide variety of by-products (spent materials) from industrial processes utilizing plant products.
1.3 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.
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Designation: D 6405 – 99
Standard Practice for
Extraction of Tannins from Raw and Spent Materials
This standard is issued under the fixed designation D 6405; 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 A5 Extraction of Raw and Spent Materials
1.1 This practice covers extracting the tannin from raw and
3. Terminology
spent materials. The water extract obtained by this method is
3.1 Definitions:
used to determine the tannin content of the original material.
3.1.1 For definitions of general leather and tanning terms
Analysis for total solids, soluble solids, and soluble non-
used in this practice refer to Definitions D 1517.
tannins of the water extract from a material provides the
3.1.2 raw material—any of the various parts of plants that
information necessary to calculate the extractable tannin con-
are used as a source of vegetable tannins.
tent of that material. The types of materials typically analyzed
3.1.3 spent material—plant tissue by-products from indus-
by this practice are products of plants such as woods, barks,
trial processes which may contain significant quantities of
leaves, nuts, fruits, roots, etc. and any of a wide variety of
vegetable tannins.
by-products (spent materials) from industrial processes utiliz-
3.1.4 tannin—an astringent substance found in the various
ing plant products.
parts of plants such as bark, wood, leaves, nuts, fruits, roots,
1.2 The values stated in SI units are to be regarded as the
etc.
standard. The inch-pound units given in parentheses are for
3.1.5 vegetable tannins—mixtures of substances (natural
information only.
products) obtained from plant tissues by water extraction
1.3 This standard does not purport to address all of the
which have the chemical and physical properties necessary to
safety concerns, if any, associated with its use. It is the
convert animal hides and skins into leather.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
4. Summary of Practice
bility of regulatory limitations prior to use.
4.1 The sample of material to be analyzed for tannin content
2. Referenced Documents is first brought to moisture equilibrium with the laboratory
atmosphere (that is, wet materials such as spent materials are
2.1 ASTM Standards:
2 first dried under ambient laboratory conditions) and then
D 1517 Definition of Terms Relating to Leather
ground sufficiently to pass through a sieve. This ground sample
D 4903 Test Method for Total Solids and Water in Vegetable
2 is then extracted with water in a steam-jacketed extractor.
Tanning Material Extracts
D 4904 Practice for Cooling Analytical Solutions
5. Significance and Use
D 6401 Test Method for Determining Non-Tannins and
2 5.1 This practice provides a standard procedure for obtain-
Tannin in Extracts of Vegetable Tanning Materials
ing the water-soluble materials (including tannins) from any
D 6402 Test Method for Determining Soluble Solids and
2 material that can be prepared for and charged to the steam-
Insolubles in Extracts of Vegetable Tanning Materials
jacketed extractor. The extraction solutions are then analyzed
D 6403 Test Method for Determining Moisture in Raw and
2 according to Test Methods D 4903, D 6401, and D 6402.
Spent Materials
D 6404 Practice for Sampling of Vegetable Materials Con-
6. Apparatus and Reagents
taining Tannin
6.1 Sieve, with circular openings 1.27 cm (0.50 in.) in
2.2 ALCA Methods:
diameter.
6.2 Sieve, with circular openings of 2 mm diameter (U.S.
Std. Sieve Series No. 10).
This practice is under the jurisdiction of ASTM Committee D-31 on Leather
and is the direct responsibility of Subcommittee D31.01 on Vegetable Leather. This
test method has been adapted from and is a replacement for Method A5 of the
Official Methods of the American Leather Chemists Association.
Official Methods of the American Leather Chemists Association. Available
Current edition approved May 10, 1999. Published August 1999. from the American Leather Chemists Association, University of Cincinnati, P.O.
Annual Book of ASTM Standards, Vol 15.04. Box 210014, Cincinnati, OH 45221-0014.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 6405
6.3 Glass Rods, soft glass stirring rods with rounded, 7.2 Where the original sample is too wet to be ground, or
fire-polished ends. where such grinding is likely to cause significant changes in the
6.4 Borosilicate Glass Wool, made of soft, pliable fibers. moisture content, samples of raw material shall be weighed,
6.5 Steam-Jacketed, Borosilicate Glass Extraction Appara- spread out on (canvas) trays which permit free circulation of air
tus, as described in Fig. 1. This apparatus may need to be all around the sample, and allowed to attain approximate
special ordered and custom built by a laboratory glass-blowing moisture equilibrium with the laboratory atmosphere; the
manufacturer. temperature at no time should exceed 60°C. Spent materials
6.6 Tubing, flexible, chemical and heat resistant tubing of should be similarly treated except that temperatures up to
appropriate size and length to fit onto the outlet tubes of the 100°C may be used. The partially dried sample shall then be
extractor apparatus. The tubing from the extraction chamber ground as described in 7.1.
outlet must fit into the receiving flask. 7.2.1 In all cases, the loss of moisture during such drying
6.7 Clamps, Hoffman or similar type for use on the tubing must be determined and the results of the analysis calculated to
extensions from the extractor outlets. the basis of the original moisture before drying. A second
6.8 Wiley Mill, or similar grinder. moisture shall be run on the finely ground sample. The method
6.9 Balance, analytical balance which will weigh up to 100 of determining these moi
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