Colour Fastness Grades and What They Mean

Colour Fastness Grades and What They Mean

Colour fastness grades rate how well a dyed or printed fabric resists losing colour, measured on a scale from 1 to 5 where 5 means no visible change. A grade of 4 or above is the practical bar for custom apparel that will be washed repeatedly. If you are buying blank garments or printed goods, colour fastness grades are the number to ask for, because they predict how a product behaves after twenty washes rather than how it looks on arrival.

What a Colour Fastness Grade Measures

The grade describes a change, not a quality level in the abstract. That distinction is the first thing to understand about colour fastness grades. It compares the sample before and after a defined stress against a standard grey scale.

The 1 to 5 Scale

Grade 5 shows no change, grade 4 shows a slight change that a trained eye can see, grade 3 shows a noticeable change, and grades 1 and 2 show obvious loss. Each half step matters, so a 3 to 4 result is different from a 4. The scale is applied both to the fabric's colour loss and to how much colour transfers onto adjacent material, which is why two numbers often appear together.

Which Stress Each Test Applies

Colour fastness grades are reported per stress rather than as one score. Fastness is measured against several stresses, and a fabric can grade well on one and poorly on another. A dark cotton that survives washing can still transfer colour onto a pale garment in the same load, and a print that resists water can fade in strong light. Reading a single number as a general quality score is the most common mistake with colour fastness grades.

Why Grade 4 Is the Practical Bar

Grade 4 corresponds to a change most customers will not notice across the life of a garment, which is why good ranges cluster there. Grades 1 to 3 produce complaints, particularly on dark colours where fading is more visible against the original shade. Buying to grade 4 removes a whole category of returns without adding much cost, because most reputable mills already produce at that level.

For a print rather than a dyed fabric, the same logic applies to the decoration. Ink durability is usually reported as a wash result, and the methods used to check it are described in this guide to wash testing custom prints, methods and limits. The behaviour of a dye inside the fibre is covered in this guide to colorfastness and wash durability in prints.

The Tests Behind the Grades

Four stresses account for most reported results, and each produces a separate number.

Washing

A sample is washed under a defined temperature and detergent, then compared against the grey scale. Washing is the test most colour fastness grades come from. Colour loss and staining of adjacent fabric are rated separately, which is why a label may show two results for the same wash test. Temperature is the variable that changes the outcome most, so a result quoted without a temperature is not comparable to another result.

Rubbing and Crocking

Dry and wet rubbing tests measure how much colour transfers when the fabric is rubbed against a white cloth. Dark and saturated shades score lowest here, which is where colour fastness grades fall first. Indigo and deep red are the classic weak spots.

Light and Perspiration

Light fastness measures fading after controlled exposure, and it matters for products used outdoors and for anything displayed in a window. Perspiration fastness measures colour transfer against acidic and alkaline solutions, which is relevant for sportswear. Both are separate results, and the effect of light on a printed surface is related to the wider question compared in this guide to printing on dark garments and how the methods compare.

How Grades Are Reported

Read colour fastness grades as a set rather than as a headline figure. A useful report names the test, the conditions and the two numbers. A wash fastness of 4 to 5 with a staining result of 4, run at 40 degrees, tells you something you can act on. A single line reading 4, with no method stated, tells you very little. Ask for the test method reference as well, because results from different methods are not directly comparable.

Fibre composition affects the expected range too. Cellulose fibres dye differently from synthetics, and a blend takes on the weaker characteristics of its components, which is why the differences between base fabrics are set out in this guide to cotton versus polyester for custom apparel printing and in these notes on tri-blend fabric for print on demand.

What Drives a Poor Grade

Dye class is the main factor. Some dye families bond more firmly to a fibre than others, and a mill choosing a cheaper dye to hit a colour can produce a fastness result that is technically acceptable and practically poor. Poor colour fastness grades usually trace back to the dye bath. Insufficient rinsing after dyeing leaves unfixed dye on the surface, which shows up in a crocking test.

Finishing treatments change the result either way. A softener can improve hand feel while reducing wet rubbing performance, which is a trade off worth knowing about before a fabric is specified for a colour sensitive product. Colour accuracy is separate from fastness, and the two are often confused, as explained in this guide to color management for print on demand production.

Using Grades When Choosing a Supplier

Ask for colour fastness grades per colour rather than per garment style, because the result changes with the shade. A supplier that can produce the data has tested, and one that offers a general assurance has not. Where a grade falls below 4, ask the intended use, since a fabric sold for a cushion cover may legitimately carry a lower wash result.

Where the grade is not available, generate your own result. Wash a sample five times with a white cloth included and check whether the white cloth picks up colour. That simple test reproduces the practical question a customer will ask.

Testing Without a Laboratory

A seller does not need a lab. Wash a sample at the temperature the care label states, dry it, and compare it against an unworn sample under the same light. Include a white cloth in the load to detect transfer. Photograph both. Three washes reveal most of what a customer will see, and give you a colour fastness grades result of your own.

Colour fastness grades turn a vague quality conversation into a number, which is why they are worth asking for before a range is committed. Target grade 4 or above, ask for the test method and the colour it applies to, and verify with a wash test of your own. The custom product catalog CatKissFish produces covers apparel blanks and printed goods with 2-3 day turnaround on most orders and shipping from US warehouses, and samples are the cheapest way to confirm any of them. Grade 4 or above is the practical bar for custom apparel.

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