ASTM standards to determine the fiber content in linen fibers

To determine the fiber content in linen fibers, especially in blended yarns or fabrics, the ASTM provides several standard test methods that focus on quantitative chemical analysis and microscopic identification. These are particularly useful when flax (linen) is blended with fibers like cotton, polyester, viscose, or synthetics.

ASTM standards to determine fiber content in linen fibers

1. ASTM D629 – 15 (Reapproved 2020)-standard test methods for quantitative analysis of textiles: This is the primary ASTM method for determining the percentage composition of fibers in textile products. It applies to blended fibers including linen (flax) with cotton, wool, polyester, rayon, etc. The test methods include chemical dissolution using selective solvents, mechanical separation techniques and calculation of fiber percentages by weight. For example: If linen is blended with cotton, a specific reagent dissolves cotton while leaving linen intact, allowing for separation and quantification.

2. ASTM D276 – 20- Standard test methods for identification of fibers in textiles: This is for qualitative identification of fibers (e.g., confirming linen is present). The test methods used for this standard include: Microscopy that is is used for flax fibers which have distinctive nodes and irregular cross-sections; burn tests, solubility tests and staining techniques used for verifying linen vs cotton vs viscose, especially when visually similar.
3. ASTM D1577 – 07 (Reapproved 2020)-standard test methods for linear density of textile fibers: This focuses on fiber fineness, it helps in differentiating fiber types during analysis.

4. ASTM D1909 – 13 (Reapproved 2020)- Standard table of commercial cotton yarn numbers: This test method supports classification when linen is blended with cotton, by referencing standard count systems.

Common use-cases for ASTM D629 (quantitative analysis):

Additional tools

• FTIR (Fourier Transform Infrared Spectroscopy): Sometimes used for blended fiber analysis.
• NIR (Near-Infrared): Rapid analysis of fiber blends, though not standardized under ASTM yet.