Dyeing and colour matching: Pantone, dye lots and colour fastness

Colour is the line that most often turns into a dispute between importer and factory, because the two sides speak different languages: the importer describes a colour in words, the factory executes a number. Anyone who wants a specific colour has to learn the language of numbers.

How are t-shirts dyed?

There are three common routes. First, yarn dyeing before knitting, the most colour-stable and the most expensive, used for stripes and melange. Second, fabric dyeing after knitting and before cutting, the most common route for t-shirts. Third, garment dyeing after sewing, which gives a deliberately washed look and is less dimensionally stable. The route the factory chooses affects both price and colour uniformity, so ask which it is.

What is a dye lot and why is it the root of the problem?

Fabric is dyed in baths, and each bath is a separate lot. Two lots dyed to the same recipe can differ slightly because of variation in temperature, time, water hardness and the greige fabric batch. That variation is inherent to the industry and cannot be eliminated, but it can be controlled. The practical rule: all the quantity of one colour should be dyed in a single lot wherever possible. If it must split across two, require that pieces from different lots are never mixed inside one carton, and that cartons are marked with the lot number.

Pantone: how to use it correctly

Specify one reference Pantone per colour and write it into the contract. But note a point many miss: paper and textile Pantone references differ, and converting a colour from paper to fabric never gives an exact match, because a fabric surface absorbs light differently. Always ask for a physical dye lab dip on the same fabric at the same weight, and sign it with the date. That signed swatch is the real reference, not the Pantone number alone.

Acceptable tolerance

Write into the contract that colour is judged against the approved swatch under standard lighting, and that deviation must not exceed an agreed limit. Without that clause the dispute becomes a matter of opinion. Also require assessment under more than one light source, because metamerism is common: two colours that match under daylight can diverge under artificial light.

Colour fastness: three tests that matter

• Fastness to washing: does the colour fade or bleed onto other garments after a stated number of washes.
• Fastness to rubbing: does colour transfer when the fabric is rubbed dry and wet. Critical on dark shades.
• Fastness to perspiration and light: important for sportswear and sunny markets.

These are standard laboratory tests; ask for the report with the shipment rather than a promise of one.

Difficult colours to watch

Bright red, royal blue, deep black and fuchsia are the hardest to reproduce and the most prone to bleeding. Pale and pastel shades are easier to hold but reveal any contamination in the fabric. If your brand colour falls in the difficult group, double the care in approval and never approve from an image on screen.

Frequently asked questions

Can I approve colour from a photograph? No. Your screen and the factory's screen render the same colour differently. The only reference is a physical swatch.

Is there a minimum per colour? Yes. Each colour is a separate dye cycle with its own minimum, which is why cutting colours lowers cost more than cutting quantity.

What if the colour differs from what was approved? With a written clause and a known tolerance, you have grounds to reject or claim. Without one, it comes down to negotiation.

We send an approved lab dip on your fabric at your weight before production, and require a single dye lot per colour.