ISO standards to determine the colorfastness of hemp fibers
The colorfastness of hemp fibers (which are a type of cellulose/vegetable fiber, similar to cotton or linen) is determined using the general ISO 105 series of standards for textiles. There is no single ISO standard exclusively for hemp; instead, the relevant parts of the ISO 105 series are applied based on the specific type of exposure being tested. The most common ISO standards used to determine colorfastness for hemp fabrics include:
ISO 105-B02 (Colorfastness to light): This standard determines the resistance of the color to fading when exposed to an artificial light source (xenon arc lamp) that simulates natural daylight. Hemp is naturally UV-resistant, so this test is critical.
ISO 105-C06 (Colorfastness to washing): This determines the resistance of the color to change or transfer when subjected to domestic or commercial laundering procedures using a reference detergent (various test options, e.g., A2S, C2S, are available for different temperatures/conditions).
ISO 105-X12 (Colorfastness to rubbing/crocking): Determines the resistance of the color to mechanical rubbing/friction, both dry and wet. It assesses how much color transfers to a white rubbing cloth.
ISO 105-E04 (Colorfastness to perspiration): Determines the resistance of the color to change or transfer when exposed to acidic and alkaline perspiration solutions, simulating human sweat.
ISO 105-E01 (Colorfastness to water): This standard determines the resistance of the color to change or transfer when exposed to water (e.g., rain, accidental soaking).
Assessment principles
In all these tests, the color change of the hemp specimen and the staining of adjacent undyed fabrics (often a multi-fiber strip containing cotton, wool, polyester, etc., as specified in ISO 105-F) are evaluated using:
- Grey scale for assessing change in color (ISO 105-A02): To rate the fading or change in the specimen's color.
- Grey scale for assessing staining (ISO 105-A03): To rate how much color is transferred from the specimen to the adjacent fabrics.
The results are typically reported on a scale of 1 to 5, where 5 is the best fastness (no change/staining) and 1 is the worst (severe change/staining).