Custom Knitted Bag Colour Matching: Lab Dips, Delta E Tolerance and Shade Approval for Brand Programmes

What a Colour Match Costs on a Knitted Bag Programme

A custom knitted bag colour match adds about 7% to the unit cost of a standard shade and about 10 working days to the schedule, and both figures are set by the dye lot rather than by the knitting.

The cost is easy to misread because it rarely appears as a single line item. A stock shade programme buys yarn that already exists; a matched shade programme books a dye lot, and a dye lot has a minimum. On a knitted bag body the usual minimum is around 300 kg, which is more yarn than a 100-piece first run consumes, and the surplus is held against the repeat. That holding is the real cost of matching, and it is why the premium is quoted as a percentage of the unit rather than as a set-up fee.

The schedule cost behaves the same way. Sampling on a knit programme runs 7 working days from an approved artwork and technical pack, and a custom shade does not shorten that — it lengthens it, because the dip has to be knitted, not just dyed. A dip presented on yarn alone is not a dip; it is a cone, and a cone does not carry loop geometry. The only honest approval surface is a knitted swatch from the production bed, at the production gauge, in the production yarn.

The Four Numbers Behind a Shade Approval Decision

Four numbers decide whether a knitted bag shade is approved — Delta E against the brand reference, the dye-lot minimum, the number of dip rounds, and the colourway count — and the first is the only one most briefs state.

Delta E is the acceptance figure and it belongs in the technical pack next to the GSM, not in an email thread. The dye-lot minimum decides whether a matched shade is viable at the ordered volume at all, and on small programmes it is the number that turns a custom shade into a stock-shade conversation. Dip rounds decide the calendar, because each round is a physical iteration on the bed rather than a digital revision. Colourway count decides the set-up arithmetic, since MOQ is stated per style and per colourway. A programme that fixes all four before sampling starts rarely needs a third round.

Delta E target

1.0 or better under D65, measured on the finished knit against the brand reference

Dye-lot minimum

About 300 kg for a custom dope-dyed or piece-dyed shade

Dip rounds

Two on average, about 30% of programmes need a third

Colourway count

MOQ 100 pcs applies per style and per colourway, not per order

Metamerism index

Below 0.5 across D65, TL84 and illuminant A

Sampling window

7 working days from approved artwork, technical pack and yarn booking

Lab Dip Rounds: How Many It Takes and What Each One Costs

A custom knitted bag shade reaches approval in two dip rounds on average, about 30% of programmes need a third, and every extra round costs roughly three calendar days plus one yarn set-up on the sampling bed.

The second round exists for a reason that has nothing to do with competence. The first dip is mixed against a spectrophotometer reading of the reference; the second is corrected against a knitted swatch of the first. Those two readings differ, because the reference is usually a flat chip and the swatch is a loop structure, and the instrument sees the difference as a shade error rather than as a construction difference. Once the loop geometry is in the measurement, the correction is usually small and the third round becomes unnecessary.

• Round one: shade mixed to the instrument reading of the brand reference, knitted at production gauge, about three days.
• Round two: corrected against the knitted swatch from round one, typically the approval round.
• Round three: needed on about 30% of programmes, usually where the reference is a printed rather than a dyed standard.
• Each round beyond the second adds a yarn set-up, and on a sampling bed a set-up is the dominant cost.
• Requesting two dip options per round costs little extra and removes one full iteration in most cases.

Reading Delta E: Tolerance Bands That Survive a Retail Audit

Delta E 1.0 is the acceptance figure for a knitted bag body measured against a brand reference under D65; between 1.0 and 1.5 the difference is visible to a trained eye on adjacent panels, and above 2.5 it is visible to a shopper across a shelf.

The formula matters as much as the figure. Delta E calculated under CIELAB overstates the difference in saturated blues and reds, which is exactly where brand palettes cluster, so the figure quoted in a specification should be CIEDE2000 unless the brief says otherwise. A supplier quoting 1.2 under CIELAB may be inside 1.0 under CIEDE2000, and a specification that does not name the formula produces an argument that neither side can settle. Naming it costs one line in the technical pack.

Why Yarn Type Moves a Shade More Than the Dye Recipe

The same dye recipe can read up to 1.8 Delta E differently on a 300D polyester body than on a 600D recycled rPET body at identical gauge, because filament cross-section and staple length change how the surface scatters light.

This is the most under-specified line in a knitted bag technical pack. A brand team approves a shade on a 300D body, the value engineering conversation moves the construction to a recycled 600D to meet a sustainability target, and the approved shade is now out of tolerance without a single change to the dye recipe. The fix is to re-approve on the final yarn, not to argue about whether the difference is real. Where a programme intends to run both, the shade should be matched on each and the two standards held separately, with the Delta E figure stated per yarn.

Metamerism and Light Source: The Approval Conditions Buyers Forget

A shade matched under one light source can shift measurably under another, and the metamerism index should be held below 0.5 across D65, TL84 and illuminant A before a knitted bag colourway is released.

Metamerism is the failure that reaches the customer rather than the lab. Two surfaces match under the light box in the sampling room and separate under the lighting on a retail floor, because the two reflectance curves are different even though the two readings agree. A knitted body and an applied trim are the classic pairing: the body is dyed in one process, the trim tape in another, and they agree under D65 and disagree under the warm lighting of a store. Requiring the index to be reported across three illuminants costs nothing and removes an entire class of complaint.

Colourway Count and the Set-Up Cost Behind Each Shade

Four colourways on a 2,000-piece knitted bag programme add about 11% to the unit cost, because each colourway is a separate yarn set-up on the bed and MOQ applies per style and per colourway rather than per order.

The arithmetic is worth stating plainly, because it is where most colour programmes lose their cost target. A 2,000-piece order is not one programme in four colours; it is four programmes of 500, each of which has to clear MOQ 100 pcs and each of which carries its own dye lot. The saving available is not in the knitting — it is in sharing the structure. One knitting programme across four shades means only the yarn changes, not the stitch file, and that keeps the premium to the yarn rather than compounding it with a second programming charge.

What Colour Fastness a Matched Shade Has to Hold

A matched knitted bag shade has to hold grade 4 or better to AATCC 8 for rubbing, grade 4 after an AATCC 61 2A wash, and grade 4-5 to ISO 105-B02 for light, because a shade that drifts after one wash has not been matched at all.

Fastness and matching are the same problem viewed at different distances in time. A dye formulation pushed hard to hit a tight Delta E on a difficult shade can meet the tolerance on day one and fail it by week six, particularly on deep navies and bright reds where unfixed dye sits near the surface. That is the argument for testing the approval swatch rather than a laboratory standard: the swatch carries the actual formulation, the actual yarn and the actual finishing route, and a fastness result taken from it predicts the bulk. Where a programme is running a deep shade, washing the approval swatch once before reading Delta E removes the drift from the measurement.

Frequently Asked Questions

People Also Ask

Specify the Tolerance, Not the Recipe

A colour argument on a knitted bag programme is almost never about competence. It is about a specification that named a colour and not a tolerance, a light source and not a formula, a cone and not a swatch. Four lines in the technical pack — Delta E, illuminant, measurement surface and yarn count — turn shade approval from an exchange of opinions into a measurement both sides already agreed to accept.

For the branding methods that sit on a matched surface, see knitted bag logo application methods. For the structure of the volume commitment behind a shade booking, see custom knit bags, and for how a shade behaves across a yarn range, see knitted bag colour fastness by yarn.