ASTM D6402-99(2020)

Standard Test Method for Determining Soluble Solids and Insolubles in Extracts of Vegetable Tanning Materials

SIGNIFICANCE AND USE
5.1 This test method is used to determine the proportion of the total solids which are soluble solids and that proportion which are insoluble solids in a solution of tannin extract or in the water extract from raw or spent materials prepared for tannin analysis.  
5.2 The specimens are aliquots from the analytical solutions prepared from tannin extracts or the water extract solutions prepared from raw or spent materials.  
5.3 The soluble solids are defined as the portion of the total solids which are dissolved in the water and pass through a filter prepared by depositing a layer of Kaolin paste onto a standard filter paper.  
5.4 The insolubles are defined as the portion of the total solids which do not pass through the standard filter paper prepared with the layer of Kaolin paste.  
5.5 The results of this test method are dependent on a great many variables but particularly upon:  
5.5.1 The temperature conditions under which the solutions were prepared and stored and the temperature at which the current analysis is performed;  
5.5.2 The uniformity and consistency of the Kaolin paste layer deposited onto the filter paper;  
5.5.3 The rate of solution run-out from the pipette; etc. It is, therefore, essential that the method be followed exactly in order to obtain reproducible results both among specimens within a laboratory and for analyses between laboratories.
SCOPE
1.1 This test method is intended for use in determining the quantity of soluble solids and insolubles in solutions of tannin extracts, water extracts of vegetable tanning materials, or tanning liquors. This test method is applicable to the analysis of liquid, solid, pasty, and powdered tannin extracts and to the water extracts of raw or spent materials.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 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.

General Information

• Status: Published
• Publication Date: 30-Nov-2020
• ICS: 59.140.10 - Processes and auxiliary materials
• Technical Committee: D31 - Leather
• Drafting Committee: D31.01 - Vegetable Leather

Relations

• Refers: ASTM D4905-99(2009) - Standard Practice for Preparation of Solution of Solid, Pasty and Powdered Vegetable Tannin Extracts
• Effective Date: 01-Apr-2009
• Refers: ASTM D6405-99(2009) - Standard Practice for Extraction of Tannins from Raw and Spent Materials
• Effective Date: 01-Apr-2009
• Refers: ASTM D4902-99(2009) - Standard Test Method for Evaporation and Drying of Analytical Solutions
• Effective Date: 01-Apr-2009
• Refers: ASTM D4903-99(2009) - Standard Test Method for Total Solids and Water in Vegetable Tanning Material Extracts
• Effective Date: 01-Apr-2009
• Refers: ASTM D6403-99(2009) - Standard Test Method for Determining Moisture in Raw and Spent Materials
• Effective Date: 01-Apr-2009
• Refers: ASTM D4901-99(2009) - Standard Practice for Preparation of Solution of Liquid Vegetable Tannin Extracts
• Effective Date: 01-Apr-2009
• Refers: ASTM D4901-99(2004) - Standard Practice for Preparation of Solution of Liquid Vegetable Tannin Extracts
• Effective Date: 01-Apr-2004
• Refers: ASTM D4903-99(2004) - Standard Test Method for Total Solids and Water in Vegetable Tanning Material Extracts
• Effective Date: 01-Apr-2004
• Refers: ASTM D4905-99(2004) - Standard Practice for Preparation of Solution of Solid, Pasty and Powdered Vegetable Tannin Extracts
• Effective Date: 01-Apr-2004
• Refers: ASTM D6405-99(2004) - Standard Practice for Extraction of Tannins from Raw and Spent Materials
• Effective Date: 01-Apr-2004
• Refers: ASTM D6403-99(2004) - Standard Test Method for Determining Moisture in Raw and Spent Materials
• Effective Date: 01-Apr-2004
• Refers: ASTM D4902-99(2004) - Standard Test Method for Evaporation and Drying of Analytical Solutions
• Effective Date: 01-Apr-2004
• Refers: ASTM D6403-99 - Standard Test Method for Determining Moisture in Raw and Spent Materials
• Effective Date: 10-May-1999
• Refers: ASTM D4903-99 - Standard Test Method for Total Solids and Water in Vegetable Tanning Material Extracts
• Effective Date: 10-May-1999
• Refers: ASTM D6405-99 - Standard Practice for Extraction of Tannins from Raw and Spent Materials
• Effective Date: 10-May-1999

Overview

ASTM D6402-99(2020): Standard Test Method for Determining Soluble Solids and Insolubles in Extracts of Vegetable Tanning Materials sets out a precise laboratory protocol for quantifying soluble solids and insolubles in solutions prepared from vegetable tannin extracts or water extracts of raw or spent tanning materials. This widely used test method helps manufacturers, researchers, and quality control laboratories in the leather and tanning industries accurately analyze the composition of various tannin preparations.

Soluble solids are defined as materials dissolved in water that pass through a special filter, while insolubles are materials that cannot pass through the filter setup described in the method. Precise adherence to the procedure is essential for obtaining reproducible and reliable results.

Key Topics

• Purpose: Determines the proportions of soluble and insoluble solids in tannin extracts and water-extracted vegetable tanning materials.
• Applicable Materials: Covers analysis for liquid, solid, pasty, and powdered tannin extracts, as well as water extracts from both raw and spent tanning materials.
• Definitions:
  • Soluble Solids: Non-volatile components that dissolve in water and pass through a kaolin-coated filter paper.
  • Insolubles: Non-volatile components that do not pass through this filter.
• Testing Process:
  • Preparation of specified solutions from the sample material.
  • Filtration using kaolin-coated standard filter paper.
  • Drying and weighing procedures for both total solids and soluble solids.
  • Calculation of insolubles by subtraction.

Key variables affecting accuracy include:

• Temperature conditions during solution preparation and analysis.
• Uniformity and consistency of the kaolin film on the filter paper.
• Rate of solution run-out from pipettes.

Applications

The ASTM D6402 standard is critical for:

• Quality Control: Ensuring the consistent composition of vegetable tannin extracts used in leather production.
• Product Development: Evaluating raw material quality and effects of process changes in tanning operations.
• Research: Comparing different vegetable tannins, analyzing raw/spent extracts, and developing new tanning formulations.
• Regulatory Compliance: Supporting documentation for meeting industry and trade quality standards.

Accurate determination of soluble and insoluble content aids in assessing the purity and usability of tannin materials, thus directly impacting product performance and process efficiency in the tanning industry.

Related Standards

For comprehensive tannin analysis and related operations, the following ASTM standards are frequently referenced alongside ASTM D6402:

• ASTM D4901: Preparation of Solution of Liquid Vegetable Tannin Extracts
• ASTM D4902: Evaporation and Drying of Analytical Solutions
• ASTM D4903: Determination of Total Solids and Water in Vegetable Tanning Material Extracts
• ASTM D4905: Preparation of Solution of Solid, Pasty, and Powdered Vegetable Tannin Extracts
• ASTM D6403: Determining Moisture in Raw and Spent Materials

These standards work in conjunction to ensure a robust analytical framework for the leather and tanning industries.

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Keywords: ASTM D6402, soluble solids, insolubles, tannin analysis, vegetable tanning materials, leather industry, analytical test method, kaolin filter, standard laboratory procedures, quality control.

Standards Content (Sample)

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: D6402 − 99 (Reapproved 2020)
Standard Test Method for
Determining Soluble Solids and Insolubles in Extracts of
Vegetable Tanning Materials
This standard is issued under the fixed designation D6402; 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 and Powdered Vegetable Tannin Extracts
D6403 Test Method for Determining Moisture in Raw and
1.1 This test method is intended for use in determining the
Spent Materials
quantity of soluble solids and insolubles in solutions of tannin
D6405 Practice for Extraction of Tannins from Raw and
extracts, water extracts of vegetable tanning materials, or
Spent Materials
tanning liquors. This test method is applicable to the analysis
2.2 ALCA Methods:
of liquid, solid, pasty, and powdered tannin extracts and to the
A21 Soluble Solids and Insolubles
water extracts of raw or spent materials.
1.2 The values stated in SI units are to be regarded as 3. Terminology
standard. No other units of measurement are included in this
3.1 Definitions:
standard.
3.1.1 insolubles—non-volatile materials present in tannin
1.3 This standard does not purport to address all of the extracts and raw or spent materials that are dissolved or
safety concerns, if any, associated with its use. It is the suspended in water and do not pass through a filtering process
responsibility of the user of this standard to establish appro- described in this method.
priate safety, health, and environmental practices and deter-
3.1.2 soluble solids—non-volatile materials present in tan-
mine the applicability of regulatory limitations prior to use.
nin extracts and raw or spent materials that are dissolved or
1.4 This international standard was developed in accor-
suspended in water and pass through a filtering process
dance with internationally recognized principles on standard-
described in this method.
ization established in the Decision on Principles for the
4. Summary of Test Method
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
4.1 An aliquot of the analytical solution prepared from
Barriers to Trade (TBT) Committee.
tanninextracts(PracticesD4901orD4905)orthewaterextract
fromraworspentmaterials(PracticeD6405)isdriedovernight
2. Referenced Documents
in a forced-air oven (Test Method D4902) and the quantity of
2.1 ASTM Standards: solid residue remaining is determined and used to calculate the
D4901 Practice for Preparation of Solution of Liquid Veg- total solids for that sample (Test Method D4903). Another
etable Tannin Extracts aliquot of the same solution is passed through a specified
D4902 Test Method for Evaporation and Drying of Analyti- filtering procedure and the quantity of solid residue remaining
cal Solutions
in the filtrate is determined and used to calculate the soluble
D4903 Test Method for Total Solids and Water in Vegetable solids for that sample. The difference between the total solids
Tanning Material Extracts
and the soluble solids is defined as the insolubles for that
D4905 Practice for Preparation of Solution of Solid, Pasty sample.
5. Significance and Use
This test method is under the jurisdiction ofASTM Committee D31 on Leather
5.1 This test method is used to determine the proportion of
and is the direct responsibility of Subcommittee D31.01 on Vegetable Leather. This
the total solids which are soluble solids and that proportion
test method has been adapted from and is a replacement for Method A21 of the
which are insoluble solids in a solution of tannin extract or in
Official Methods of the American Leather Chemists Association.
Current edition approved Dec. 1, 2020. Published December 2020. Originally the water extract from raw or spent materials prepared for
approved in 1999. Last previous edition approved in 2014 as D6402 – 99 (2014).
tannin analysis.
DOI: 10.1520/D6402-99R20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Official Methods of the American Leather Chemists Association. Available
Standards volume information, refer to the standard’s Document Summary page on from the American Leather Chemists Association, University of Cincinnati, P.O.
the ASTM website. Box 210014, Cincinnati, OH 45221-0014.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6402 − 99 (2020)
5.2 The specimens are aliquots from the analytical solutions 6.8.1 Suspend 1.0 g kaolin in 100 mL distilled water. The
prepared from tannin extracts or the water extract solutions pH value should be between 4.5 and 6.0 after 5 min.
prepared from raw or spent materials. 6.8.2 A mixture of 2.0 g kaolin and 200 mL distilled water
is shaken for 10 min and the mixture filtered through the
5.3 The soluble solids are defined as the portion of the total
standard filter paper. A 100 mL aliquot of the clear filtrate
solidswhicharedissolvedinthewaterandpassthroughafilter
should have less than 0.001 g of residue after evaporation and
prepared by depositing a layer of Kaolin paste onto a standard
oven-drying in a platinum dish.
filter paper.
6.9 Balance, analytical balance which will weigh up to
5.4 The insolubles are defined as the portion of the total
100 g with an accuracy of 6 0.1 mg (6 0.0001 g).
solids which do not pass through the standard filter paper
prepared with the layer of Kaolin paste. 6.10 Drying Oven, a forced-air convection oven (or
mechanical-convection draft oven) capable of maintaining a
5.5 The results of this test method are dependent on a great
temperature of 100 6 2.0 °C.
many variables but particularly upon:
5.5.1 The temperature conditions under which the solutions 6.11 Thermometer, accurate to 6 0.2 °C used to check and
were prepared and stored and the temperature at which the monitor the oven set point.
current analysis is performed;
6.12 Dessicator, any convenient form or size, using any
5.5.2 The uniformity and consistency of the Kaolin paste
normal dessicant.
layer deposited onto the filter paper;
5.5.3 The rate of solution run-out from the pipette; etc. It is,
7. Test Specimen
therefore, essential that the method be followed exactly in
7.1 The specimen shall consist of 100 mL of the solution
order to obtain reproducible results both among specimens
prepared as described in Practices D4905, D4901,or D6405
within a laboratory and for analyses between laboratories.
and after passing through the filtering process described in this
test method.
6. Apparatus and Reagents
6.1 Tannin Dish, crystallizing dish, borosilicate glass, 50
8. Procedure
mm tall, 70 mm outside diameter. The bottom corner shall be
8.1 Place a pleated filter paper in a 100 to 125 mm funnel.
rounded to a radius of 6 mm, the bottom shall be flat and not
8.1.1 Fold the filter paper to contain 32 evenly divided
cupped in the center, and the top edge shall be rounded and
pleats.
polished.
8.2 Add to 2.0 g of kaolin in a clean glass container (a 250
6.2 Watch Glass, a suitable size (approximately 150 mm
mL beaker works well) 25 mL of the well-mixed analytical
diameter) to be used as a cover for the funnel and filter paper
solution (which has been prepared as
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