ASTM D7674-14a(2021) PDF

Overview

ASTM D7674-14a(2021) - Standard Test Method for Hexane/Petroleum Ether Extract in Wet Blue and Wet White - provides a quantitative method to determine the amount of solvent-soluble material in leather intermediate products known as wet blue and wet white. These materials refer to leather that has been tanned (wet blue, typically chrome-tanned; wet white, typically alternative tanned) but not yet finished. The method uses hexane or petroleum ether as extraction solvents to quantify extractable substances such as fats and oils, which are critical in the leather manufacturing process.

This standard is issued by ASTM International and aligns with global standardization principles as recognized by the World Trade Organization Technical Barriers to Trade (TBT) Committee. It is widely recognized across the leather industry for quality control and material specification purposes.

Key Topics

• Scope and Purpose:

  • Quantifies solvent-soluble (hexane or petroleum ether) materials in wet blue and wet white leathers.
  • Applicable to all types of wet blue and wet white samples.

• Sample Preparation:

  • Samples can be tested as received (wet state) or after drying and grinding, following referenced ASTM practices for preparation and sampling.
  • Extraction is carried out using either a Soxhlet or Soxtec-type apparatus.

• Extraction and Analysis:

  • The specimen is extracted with hexane or petroleum ether.
  • Post-extraction, the extract is dried, cooled, and weighed to determine the amount of extractables on a moisture-free basis.
  • The moisture content is measured with associated ASTM test methods to ensure accurate reporting.

• Reporting:

  • Results are reported as a percentage of extractables on a moisture-free basis, with the condition of the specimen and extraction apparatus specified in documentation.

• Precision:

  • The method includes defined limits for repeatability and reproducibility, established through collaborative interlaboratory studies.
  • Users are advised to follow all recommended safety practices when handling solvents.

Applications

ASTM D7674-14a(2021) is widely used in the following contexts:

• Leather Manufacturing: Ensures wet blue and wet white meet quality and performance specifications for downstream processes such as dyeing, finishing, or splitting.
• Quality Control: Validates consistency in tanning operations and detects excess oils or residual chemicals that may affect product durability and physical properties.
• Product Development & Research: Assists in the comparative analysis of new tanning systems or chemical formulations by providing quantitative extractable results.
• Supply Chain Verification: Assures buyers and regulatory agencies of conformity to industry and international standards for leather processing.

By controlling the extractable content in wet blue and wet white leather, manufacturers can improve product reliability, ensure regulatory compliance, and maintain customer trust.

Related Standards

• ASTM D3495: Test Method for Hexane Extraction of Leather
• ASTM D6658: Test Method for Volatile Matter (Moisture) of Wet Blue by Oven Drying
• ASTM D6659: Practice for Sampling and Preparation of Wet Blue and Wet White for Physical and Chemical Tests
• ASTM E177: Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• ASTM E691: Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method

Keywords

wet blue, wet white, hexane extraction, petroleum ether extract, leather testing, solvent extraction, Soxhlet, Soxtec, ASTM D7674, extractables, leather industry standards, fat content, oil content, leather quality assurance, solvent-soluble material, leather manufacturing compliance