ISO standards to determine the colorfastness of hemp fibers

Determining the colorfastness of hemp fibers is crucial for quality control, especially when the fiber is dyed or used in blend fabrics. While there isn't a standard specifically titled ‘ISO for Hemp Fiber Colorfastness,’ spinners and textile manufacturers rely on a set of general, internationally recognized ISO 105 standards designed for all textile materials, including natural fibers like hemp. The ISO 105 series outlines various tests to determine how resistant the color of a textile is to environmental and processing factors.

ISO 105 standards for hemp fiber colorfastness

The most relevant standards for assessing the durability of colored hemp fibers are:

1. Colorfastness to washing (ISO 105-C Series)

This series simulates various laundering conditions to assess color bleeding and staining. Hemp fibers must withstand these processes without significant color loss.

ISO 105-C06-Domestic and Commercial Laundering: This standards measures the resistance to washing using various detergents, temperatures, and mechanical agitation. Crucial for hemp garments.

ISO 105-C08-Domestic Laundering: Oxidative Bleach: This test method is used if the hemp fabric might be washed with chlorine or oxygen bleach.

2. Colorfastness to light (ISO 105-B Series)

These standards measure how well the color resists fading when exposed to sunlight (or artificial light sources).

ISO 105-B02: Artificial Light (Xenon Arc Fading Lamp): This is the most common method and measures fading intensity using an arbitrary Blue Wool Scale (1=poor, 8=excellent). It is essential for upholstery, curtains, and high-visibility garments.

ISO 105-B04: Artificial Weathering (Xenon Arc Fading and Rain): This test method is used for specialized outdoor applications (e.g., awnings, industrial canvas) where hemp is exposed to both light and water.

3. Colorfastness to perspiration and rubbing (ISO 105-E & X Series)

These tests assess color durability against physical contact and human body factors.

ISO 105-E04: Perspiration: This test method measures resistance to acidic and alkaline human sweat. Critical for apparel that touches the skin.

ISO 105-X12: Rubbing (Crocking): This measures the transfer of color from the hemp fiber to another fabric through mechanical rubbing (either dry or wet). It’s crucial to prevent color transfer onto other garments.

4. Colorfastness to heat and other Factors

ISO 105-P01: Dry Heat (Hot Pressing): Assesses color change when hemp fabric is ironed or pressed at high temperatures.

ISO 105-G01: Nitrogen Oxides (Fume Fading): Used for specialty items to test color resistance to atmospheric contaminants.

How is colorfastness determined?

All ISO 105 tests involve exposing a colored hemp sample alongside an undyed ‘multifiber strip’ (which contains fibers like cotton, wool, nylon, polyester, etc.) to the specific condition (e.g., washing, light).

The results are then evaluated using two key visual assessment tools:

1. Grey Scale for assessing change in colour (ISO 105-A02): Used to rate the degree of fading or change in the original hemp sample's color (Scale 5 is negligible change; Scale 1 is severe change).
2. Grey Scale for assessing staining (ISO 105-A03): Used to rate the degree of staining on the adjacent undyed multifiber strip (Scale 5 is negligible staining; Scale 1 is severe staining).

If you are manufacturing a final garment, the specific ISO 105 tests you must apply will be dictated by the end-use of the hemp product (e.g., apparel requires high resistance to C06 and E04; upholstery requires high resistance to B02).