Blue Wool Standards for Light Fastness Testing
Blue Wool Standards are a set of eight reference wool fabrics, each dyed to a specific light fastness level, used to grade how well a textile’s colour resists fading under light exposure. Grade 1 represents the poorest light fastness and grade 8 the best, creating a numerical scale that labs compare against a tested fabric’s colour change using a Grey Scale.
These SDCE-format standards (15x25cm strips) are specified in the ISO 105 B series of test methods and are essential for correlating lab results with real-world performance — apparel typically requires a minimum of grade 4, while furnishing fabrics need grade 6 or higher. Amith Garment Services also supplies mounting card free of optical brightening agents, ensuring the background doesn’t distort colour grading, along with SDCE Humidity Control Fabric used to calibrate light fastness testing machines against Standard No. 5.
Textile testing laboratories, dye houses, apparel export units, and fabric mills use Blue Wool Standards routinely during colourfastness testing and instrument calibration. Backed by 25+ years of serving India’s textile testing industry, Amith Garment Services supplies genuine, correctly-graded standards that keep your lab’s results consistent and audit-ready.
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SDCE Light Fastness Standards 1 to 8 each pattern 15x25cm
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These are a series of 8 wool fabrics dyed with specified blue dyes to give blue wool cloths ranging from very low light fastness to very high light fastness. This forms a numerical scale of 1 to 8 where 1 has the poorest light fastness, to 8 which has the best light fastness. This allows fabrics to be graded, using a Grey Scale for Change in Colour, for correlation with performance in use. This is used to predict the suitability for a given end use; typically apparel would be a minimum of grade 4 whilst furnishings would require a grade 6. They are used in the ISO 105 B series of tests and can be used in conjunction with the Humidity Control fabric for machine calibration.
- To complement the range of Blue Wool Standards we also supply specially prepared mounted card that is totally free of any optical brightening agents. This ensures mounted samples are easier to grade as the card does not show a significant Colour change. It is widely recognised that the Colour of the background can influence how an item is finally graded.
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SDCE Humidity Control Fabric
- This is an azoic dyed cotton fabric with specified fading properties, which varies with the amount of relative humidity.
- It is used as a calibration tool for light fastness testing. When the humidity of the light fastness testing machine is correctly set it will fade at an identical rate to the light fastness standard Number 5. It is supplied with a printed instruction sheet for its use to determine the correct settings for the relevant ISO 105 B series test method.
Frequently Asked Questions
Blue Wool Standards are used to evaluate the light fastness of dyed and printed textiles. The set contains eight calibrated wool fabric strips numbered 1 to 8, representing light fastness ratings from very poor to excellent. Textile laboratories expose a test sample alongside these standards and compare the degree of fading to determine the fabric's light fastness grade according to ISO 105 B test methods.
A complete Blue Wool Standards set consists of eight grades. Grade 1 fades the fastest and represents the lowest light fastness, while Grade 8 offers the highest resistance to fading. Laboratories select the appropriate standards based on the applicable testing method and the intended end use of the textile product.
Most apparel fabrics are expected to achieve a minimum light fastness rating of Grade 4 on the Blue Wool Scale. Home furnishings, upholstery fabrics, and technical textiles often require Grade 6 or higher because they are exposed to sunlight for longer periods.
A Blue Wool Standard is a calibrated reference fabric used to measure how well textile colours resist fading when exposed to light. The standards are numbered from 1 to 8 and provide an internationally recognised scale for evaluating light fastness.
During testing, the fabric sample is exposed to a controlled light source alongside the Blue Wool Standards. After exposure, the amount of colour fading is compared using the Grey Scale for Colour Change, and the Blue Wool grade with a similar fading level is assigned as the fabric's light fastness rating.
SDCE Blue Wool Standards are manufactured in accordance with ISO 105 B specifications, providing textile laboratories with consistent, internationally accepted reference materials for light fastness testing. They help ensure reliable quality control, export compliance, and accurate buyer inspection results.
Reach out to Amith Garment Services to order your Blue Wool Standards set today.