ASTM D3495-10(2023)

Standard Test Method for Hexane Extraction of Leather

SIGNIFICANCE AND USE
3.1 This test method measures the amount of hexane-soluble lubricant present in all types of leather. Adequate lubrication prevents abrasion of leather fibers during flexing. This lubrication is generally obtained from the fat liquor added at the tannery. Some lubrication is also obtained from natural grease produced during the life of the animal.
SCOPE
1.1 This test method covers the quantitative extraction of all types of leather with hexane. This test method does not apply to wet blue.  
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: 31-Aug-2023
• ICS: 59.140.30 - Leather and furs
• Technical Committee: D31 - Leather
• Drafting Committee: D31.06 - Chemical Analysis

Relations

• Refers: ASTM D3790-17 - Standard Test Method for Volatile Matter (Moisture) of Leather by Oven Drying
• Effective Date: 01-Apr-2017
• Refers: ASTM D3790-79(2012) - Standard Test Method for Volatile Matter (Moisture) of Leather by Oven Drying
• Effective Date: 01-Apr-2012
• Refers: ASTM D2813-03(2008) - Standard Practice for Sampling Leather for Physical and Chemical Tests
• Effective Date: 01-Sep-2008
• Refers: ASTM D3790-79(2006) - Standard Test Method for Volatile Matter (Moisture) of Leather by Oven Drying
• Effective Date: 01-Oct-2006
• Refers: ASTM D3790-79(2006)e1 - Standard Test Method for Volatile Matter (Moisture) of Leather by Oven Drying
• Effective Date: 01-Oct-2006
• Refers: ASTM D2813-03 - Standard Practice for Sampling Leather for Physical and Chemical Tests
• Effective Date: 01-Oct-2003
• Refers: ASTM D2813-97 - Standard Practice for Sampling Leather for Physical and Chemical Tests
• Effective Date: 10-Apr-1997
• Refers: ASTM D3790-79(1996) - Standard Test Method for Volatile Matter (Moisture) of Leather by Oven Drying
• Effective Date: 27-Apr-1979
• Refers: ASTM D3790-79(2001) - Standard Test Method for Volatile Matter (Moisture) of Leather by Oven Drying
• Effective Date: 27-Apr-1979

Overview

ASTM D3495-10(2023), Standard Test Method for Hexane Extraction of Leather, is an internationally recognized test method developed by ASTM International. This standard specifies procedures for quantifying the amount of hexane-soluble lubricants present in all types of leather, except wet blue. These lubricants, derived from fat liquor and natural animal grease, are essential for maintaining the softness, durability, and abrasion resistance of leather during use.

The test enables leather manufacturers, processors, and quality assurance professionals to assess and regulate the lubricating content of leather products, ensuring optimal performance and consistency across diverse applications. The method is designed with strict adherence to international standardization principles established by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

Key Topics

• Hexane Extraction: Utilizes hexane as a solvent to extract soluble lubricants from ground leather samples, providing a quantitative measure of lubrication ingredients.
• Applicability: Covers all leather types except wet blue, supporting flexibility in industry practice and quality control.
• Sampling and Preparation: Emphasizes random sampling, thorough grinding, and composite sample creation for accurate and representative analysis, as detailed in referenced standards.
• Testing Equipment: Involves use of Soxhlet extraction apparatus, analytical balance, forced circulating air oven, extraction thimbles, and standardized laboratory-grade hexane.
• Precision and Reporting: Requires reporting results on a moisture-free basis and includes specific instructions for handling moisture and obtaining consistent measurements. The method defines precision levels and recommends procedures for achieving reliable and repeatable results.
• Safety Considerations: Users must establish proper safety, health, and environmental practices according to local regulations before employing this method.

Applications

ASTM D3495-10(2023) plays a critical role in the leather industry by providing a standardized approach for:

• Quality Control: Ensuring leathers meet specification requirements for lubrication, which is crucial for products exposed to repeated flexing and wear.
• Product Development: Assisting leather technologists and tanneries in formulating and evaluating fat liquors and finishes to achieve desired softness and resilience.
• Regulatory Compliance: Supporting manufacturers in demonstrating compliance with industry and international standards concerning leather processing and product safety.
• Research and Testing Labs: Facilitating comparative studies and interlaboratory testing for material performance, consistency, and statistical control.
• Consumer Assurance: Enhancing product reliability for footwear, upholstery, automotive, apparel, and other end uses where leather flexibility and longevity are critical.

Related Standards

For comprehensive and accurate leather testing, ASTM D3495-10(2023) should be considered alongside these related ASTM standards:

• ASTM D2813: Practice for Sampling Leather for Physical and Chemical Tests - essential for obtaining representative test specimens.
• ASTM D3790: Test Method for Volatile Matter (Moisture) of Leather by Oven Drying - used to determine moisture content for correct calculation of hexane-soluble matter.

Regular reference to these documents, along with ongoing adherence to the latest safety and regulatory guidelines, ensures robust and reliable testing of leather products for manufacturers and stakeholders globally.

Keywords: hexane extraction, leather testing, fat liquor, ASTM D3495, hexane-soluble lubricant, leather quality control, Soxhlet extraction, international leather standards

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: D3495 − 10 (Reapproved 2023)
Standard Test Method for
Hexane Extraction of Leather
This standard is issued under the fixed designation D3495; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope 4. Apparatus
1.1 This test method covers the quantitative extraction of all 4.1 Analytical Balance.
types of leather with hexane. This test method does not apply
4.2 Soxhlet Apparatus, consisting of a boiling flask, extrac-
to wet blue.
tion tube, and condenser.
1.2 The values stated in SI units are to be regarded as
4.3 Forced Circulating Air Oven, capable of maintaining the
standard. No other units of measurement are included in this
specified temperature.
standard.
4.4 Electric Hot Plate.
1.3 This standard does not purport to address all of the
4.5 Extraction Thimbles, fat-free, cellulose, Alundum, or
safety concerns, if any, associated with its use. It is the
fritted.
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
4.6 Absorbent Cotton, fat-free.
mine the applicability of regulatory limitations prior to use.
4.7 Steam Bath.
1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard-
5. Reagent
ization established in the Decision on Principles for the
5.1 Hexane, ACS Reagent Grade conforming to the follow-
Development of International Standards, Guides and Recom-
ing requirements:
mendations issued by the World Trade Organization Technical
5.1.1 Color (APHA)—10 max.
Barriers to Trade (TBT) Committee.
5.1.2 Density (g/mL) at 25 °C—0.687 max.
5.1.3 Boiling Range—1 mL to 95 mL, not more than 4.0 °C.
2. Referenced Documents
5.1.4 Residue After Evaporation—0.001 % max.
2.1 ASTM Standards:
5.1.5 Acidity (as CH COOH) —To pass test (limit 0.002 %).
D2813 Practice for Sampling Leather for Physical and
5.1.6 Sulfur Compounds (as S)—0.005 % max.
Chemical Tests
5.1.7 Thiophene—To pass test.
D3790 Test Method for Volatile Matter (Moisture) of
Leather by Oven Drying NOTE 1—This reagent grade hexane is generally a mixture of several
isomers of hexane (C H ), predominantly n-hexane and methylcyclopen-
6 14
tane (C H ).
3. Significance and Use
6 12
3.1 This test method measures the amount of hexane-
6. Test Specimens
soluble lubricant present in all types of leather. Adequate
6.1 The leather shall be sampled in accordance with Method
lubrication prevents abrasion of leather fibers during flexing.
D2813. Leather test specimens shall be obtained from the
This lubrication is generally obtained from the fat liquor added
composite sample prepared by random sampling, cutting, and
at the tannery. Some lubrication is also obtained from natural
mixing equal portions of leather representing the lot that is
grease produced during the life of the animal.
being analyzed. The well-mixed leather pieces shall be ground
in a mill (Wiley or equal) having a No. 5 (4 mm) sieve. The
This test method is under the jurisdiction of ASTM Committee D31 on Leather
ground leather that passes through this 4 mm sieve shall be
and is the direct responsibility of Subcommittee D31.06 on Chemical Analysis.
mixed well and used as the composite sample.
Current edition approved Sept. 1, 2023. Published September 2023. Originally
approved in 1976. Last previous edition approved in 2015 as D3495 – 10 (2015).
7. Procedure
DOI: 10.1520/D3495-10R23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
7.1 Determine the moisture content of the composite sample
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
from which the ground leather for hexane extraction is taken in
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. accordance with Test Method D3790. Determine the weight of
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D3495 − 10 (2023)
the ground leather taken from the composite sample for 9.2 State that the results are calculated on a moisture-free
moisture content at the same time and under the same ambient basis.
conditions as the weight of the ground leather taken for hexane
10. Precision and Bias
extraction.
10.1 Interlaboratory Test Data —An interlaboratory test
7.2 Weigh 5 g of ground leather taken from the composite to
was run in 1972 in which each of 7 laboratories tested duplicate
the nearest 0.001 g and record this value as W . Loosely pack
specimens from each of 15 different types of leather. All
this material in an appropriately sized extraction thimble and
laboratories tested the following leathers: chamois, yellow
cover with a pad of fat-free cotton. Place the loaded thimble in
lace, crust sheepskin, crust goatskin, vegetable-strap leather,
the Soxhlet extraction tube. Dry an ex
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