Textile Testing: Colourfastness

A colourfastness test determines a textile's ability to resist fading or the changes in colour, hue, depth, or brightness over time. When developing a new textile, we test its colourfastness against UV light, washing and dry cleaning, and rubbing to ensure textile durability.

A colourfastness to washing and dry cleaning test determines a fabric’s resistance to fading or colour loss caused by laundering. This test is used to measure colourfastness by replicating specific cleaning procedures and comparing the results against a set of five grey scales. Result 1 is the least resistant to fading and 5 the most resistant, therefore a rate of 4-5 is ideal.

It is best to approach spot cleaning a delicate fabric or garment with the utmost care, as it is targeted and can be aggressive to a specific area. Because most of our washable textiles are delicate, gentle washing using a mild washing liquid is recommended. To prevent colour loss, it is advisable to initially use a dry white cloth to remove a stain.

A colourfastness to rubbing test determines resistance to colour loss caused by friction with another fabric, this is also known as “crocking.” For upholstery textiles, this is a crucial consideration – you wouldn’t want to stand up from a dark-coloured upholstered armchair to find your white trousers had changed colour.

In performing this test, a white cloth is rubbed against the test fabric in both dry and wet forms. The amount of colour transferred to the white cloth and the colour loss from the test fabric is measured against a set of 5 grey scales. Rate 1 having the least colour loss and 5 having the most. The result helps to determine the most suitable fabric applications and usages.

A colourfastness to light test determines fabric resistance to colour loss caused by UV light exposure. The fabric is exposed to an artificial lamp that imitates natural light for 40 hours, (interior furnishing fabrics), or 100 hours, (exterior furnishings). The fabric is compared with another piece of the same kind of fabric and a standardised set of “blue scales,” subjected to the same conditions to see the degree of colour change. 

The blue scale is comprised of 8 standard blue wool swatches that are exposed to the same light environments as the test sample. The amount of fading of the sample is then assessed by comparison to the original colour, against the blue swatches and their original swatch shade.

A rating is given by the lab based on which of the 8 strips on the blue wool standard card has faded to the same degree as the test sample. This number is made available in the fabrics’ product specifications.

There are many factors that influence the results of colourfastness tests, including the composition, yarn dyeing method, dye quality, and finishing processes.

A result of 1 on the blue scale represents nearly total colour loss, so our fabrics will never have result of 1. A result of 8 indicates no colour loss; as this is impossible to achieve, a result of 7 is extremely high. A result of 5 or higher is ideal for drapery fabrics, and 4-5 or higher is considered adequate for upholstery fabrics.

Environmental conditions are harsh in Australia, particularly regarding the amount of UV light passing through the hole in the Ozone layer above us. Because our style of living and moderate climate favour transitional architecture with plenty of indoor-outdoor living areas, our homes usually have large windows that let in lots of sunlight. Therefore, even our indoor textiles placed on the boundary of outdoor areas are exposed to UV light.

Everything fades with time, including the bricks of your house, paint, and even timber floors! Though the dyeing method and quality of dye are important factors, synthetic or man-made fibres usually tend to resist fading better than natural ones do.

Acrylic, followed by polyester, is the fibre most resilient to sunlight damage. Of fabrics made of natural fibres, cotton and linen have good resistance to sun fading. However, the best option in environments with plenty of sun is solution-dyed acrylic, olefin, or polyolefin fibre.

See our Outdoor style for all seasons and any setting article.

To protect your interiors from UV damage, it is recommended to use quality curtain lining. Zepel offers multiple types of linings for different specifications.

Areas directly exposed to the sun, such as the curtain's leading edge, are the most susceptible to fading. To hide or slow down fading, flip your curtains regularly – to alternate which edge faces the sunshine and which faces the wall.

UV damage occurs from both direct and indirect sunlight. It's important to care for your upholstery by vacuuming regularly, rearranging furniture within a room, and rotating individual cushions on a regular basis. Though this does not stop the fading process completely, it makes fading more gradual and less noticeable. 

Test results provide us with specifications that we can use as a guide, but you should always consider other factors when specifying fabrics for a particular application. Ask yourself: What are the surrounding conditions? Does the house get much sun? Do the homeowners have children or pets? Do they want their drapes to be easy to maintain? Are these fabric characteristics in line with their expectations?

Like caring for your silk shirt or woollen coat, you also need to care for your interior soft furnishings to ensure they age gracefully.