How Colour Matching Works: Pantone TCX, Lab Dips and Approvals

Colour matching is the process of turning a reference colour into dyed cloth that both buyer and mill agree on before bulk runs. It works in stages: you give the supplier a physical standard, usually a Pantone TCX swatch, they dye a small sample called a lab dip to match it, you approve or reject that dip, and the approved dip becomes the target the bulk is judged against. Getting this signed off before production is what stops a full order arriving in the wrong shade.

This guide is for a buyer who has chosen a colour and now has to communicate it to a factory precisely enough that the delivered goods match what was intended. It covers the reference systems, what a lab dip and a strike-off actually are, how many rounds to expect, and the parts of colour that no process can fully control.

Start with a physical standard, not a screen

The single most common cause of a colour dispute is a reference that was never physical. A colour on your monitor, in a PDF, or in a photograph is not a specification. Screens differ, printers drift, and the same file looks different on two laptops. A supplier cannot dye to a pixel.

The trade standard for communicating a textile colour is the Pantone system, and for cloth the relevant library is TCX. TCX swatches are dyed cotton, so they show how a colour behaves in fabric rather than on paper. The paper equivalents, TPG and TPX, are cheaper and useful for early design work, but a dyed textile reference removes a layer of translation and is the better standard to hand a mill.

Reference	What it is	Best used for
Pantone TCX	Dyed cotton swatch	The working standard for dyeing cloth
Pantone TPG or TPX	Printed paper chip	Early design, mood boards, rough alignment
A physical sample you supply	Your own fabric, garment or yarn	When no Pantone number captures the exact shade
A screen colour or photo	A digital image	Not a colour standard, do not dye to it

If you have an exact shade that no Pantone number captures, send a physical swatch as the standard and say so. A mill can match to a supplied piece of cloth as readily as to a Pantone chip, provided it is a real, stable sample and not a worn or faded one.

What a lab dip is

A lab dip is a small piece of the actual fabric, dyed in the lab to match your standard before any bulk dyeing happens. It is the mill's proposal: "this is the recipe we will run, does it match?" You receive one or more dipped swatches, compare them to your standard, and either approve one or send comments for another round.

A lab dip matters because colour is recipe-dependent and fibre-dependent. The same target shade needs a different dye recipe on linen than on cotton, and different again on tencel, because each fibre takes dye differently. The lab dip is where that recipe is proven on the right cloth. Approving a lab dip on cotton does not guarantee the shade on a linen-cotton blend, so the dip must be run on the fabric you are actually buying.

Lab dips are usually submitted in twos or threes around the target, one slightly lighter, one slightly darker, so you can pick the closest and, if needed, direct the next round. At H & J Exim, colour is matched to Pantone TCX, with lab dips and strike-offs issued for approval, and the dyes used are AZO-free.

Strike-offs are the print equivalent

A lab dip proves a single solid colour. When the design is a print or a woven pattern with several colours, the equivalent approval is a strike-off: a trial run of the full artwork on the real cloth, showing every colour in the design together, the registration between them, and the scale of the repeat.

Sample	Proves	Use for
Lab dip	One solid dyed colour	Piece-dyed and plain cloth
Strike-off	A full print or woven pattern, all colours and the repeat	Prints, yarn-dyed designs, jacquards

Approve a strike-off on the same fabric and the same process that bulk will use. A print approved on a smooth base can shift noticeably when run on a textured or heavier cloth, because the surface changes how ink or dye sits.

The approval loop, and how many rounds to expect

Colour approval is iterative. A first lab dip rarely lands exactly, and one or two further rounds to close the gap is normal, not a sign of a weak supplier. Build that into the calendar rather than treating the first submission as the deadline.

What you are judging, and should state in writing:

• Which submission is approved. Sign and date the physical swatch, keep a sealed copy, and return the other to the mill. That sealed swatch, not a Pantone number, becomes the bulk standard.
• The tolerance. No two dye lots are identical, so bulk is judged within a tolerance around the approved dip, not against perfection. Agree this up front.
• The viewing light. A colour can match under one light and diverge under another, an effect called metamerism. Name the light source you will assess under, commonly D65 daylight, and note any store or warehouse lighting that matters for the end use.

On timing, colour approval sits ahead of the counter sample rather than alongside it, so allow for both in your calendar and start the lab dip as early as you can. Counter samples of the finished article then follow the colour approval, at H & J Exim about one week on woven and about ten days on knitted from an agreed specification, with samples chargeable and adjusted against the first bulk order.

What colour matching cannot fully control

A credible supplier will tell you where the limits are, and a buyer who understands them writes better specifications.

• Fibre differences. In a blend, two fibres take dye differently, so a colour can read very slightly two-toned on a linen-cotton or tencel-linen cloth. This is physics, not a defect, and it is why the dip must be on the real blend.
• Batch variation. Separate dye lots vary within tolerance. For a large order split across lots, ask how lots are controlled and whether a shade band is kept.
• Light. The metamerism above means you must fix a viewing light, or an approval made in one condition will be disputed in another.
• Texture and finish. The same dye reads differently on matte and lustrous weaves, and a finish such as stone washing lightens and softens colour. Approve on finished cloth.

Conceding these openly is more useful than a promise of a perfect match, which no dyer can honestly make.

How to run an approval well

• Send a physical standard. A Pantone TCX swatch or a real fabric sample, never only a screen colour.
• Dye on the right cloth. Insist the lab dip and strike-off use the actual fabric and finish of the order.
• Fix the viewing light in writing, and assess every submission under it.
• Agree a tolerance before bulk, so acceptance is objective.
• Seal and keep the approved swatch. It is the reference for bulk and for any future reorder.

For how sampling, minimums and approvals are structured, see private label, and for the weaves and finishes colour behaves differently across, the woven capabilities. If you have a shade to match, get in touch with your Pantone reference or a physical swatch.

Common questions

Should I use Pantone TCX, TPX or TPG?

For dyeing cloth, use TCX, because the swatches are dyed cotton and show how a colour behaves in fabric. TPX and TPG are printed paper, cheaper and fine for early design and mood boards, but a dyed textile reference is the stronger standard to give a mill. Best of all, if you have the exact shade, is a physical fabric swatch.

How many lab dip rounds are normal?

Usually one to three. A first dip that is close but not exact is expected, and a round or two to close the gap is routine. Submitting two or three swatches around the target each round speeds this up, because you can pick the nearest and direct the next attempt.

Why does my approved colour look different under store lighting?

This is metamerism: two colours can match under one light source and diverge under another. It is why you should name the viewing light, often D65 daylight, when you approve, and check the dip under the lighting the product will actually be seen in if that differs.

Does the colour match across different fabrics?

Not automatically. Each fibre takes dye differently, so a shade approved on cotton must be re-proven on linen, tencel or a blend. Always run the lab dip on the exact fabric and finish you are ordering, and expect a slight two-tone on blends where the two fibres accept dye at different rates.