Colour is the easiest thing to promise and the hardest thing to prove. A buyer approves a shade on a screen, a mill dyes a bath, and somewhere between the two a disagreement grows that no one can settle with adjectives. Therefore, serious buyers work through the same three gates: lab dip, strike-off and bulk. Handled properly, this three-stage colour approval workflow turns a subjective argument into a recorded decision.
The sequence exists for a reason. A lab dip proves the dye recipe on a small piece. A strike-off proves the print, the placement and the hand feel on a short run. Bulk then proves that the mill can repeat both at production scale. Consequently, each stage answers a different question, and skipping a stage pushes that question into the container.
This guide walks through all three stages, explains why two people can look at the same cloth and see different colours, and shows what to record before anyone signs. Above all, it treats approval as a process with evidence, not as a formality that slows the schedule down.
What the Three Stages Actually Are
Taken together, lab dip, strike-off and bulk form a single colour approval workflow with three signatures, and each signature transfers responsibility to the next stage. Each stage feeds the next. Furthermore, each stage produces a physical reference, and that reference matters more than any image, because nobody can measure a colour from a photograph.
Stage 1: Lab Dip — Approving the Colour Before the Dyebath
A lab dip is a small dyed sample that the mill prepares to match your target shade. The mill adjusts the recipe, dyes a piece, and sends it for your review. In practice, most programs need more than one round, because the first dip rarely lands exactly where you want it.
Read a lab dip with three questions in mind:
- Is the shade acceptable, or merely close? Compare it against your master standard, not against your memory of it.
- Which direction does it lean? A dip that reads slightly red or slightly green tells the mill how to adjust the recipe. Precise feedback saves a round.
- Under which light did you judge it? Record the light source, because the same sample changes appearance between daylight and store lighting.
Send your comments as a written instruction rather than a photo alone. For instance, “dip 2 is acceptable; dip 3 reads too red in the weft” gives the colourist something to work with, while “not right” does not. If you want the underlying measurement language, the ISO committee that handles colour measurement and colour-fastness methods explains its scope on the ISO/TC 38/SC 1 page, and ISO 105-J03 covers the calculation of colour differences. You can look up its current edition in the ISO Online Browsing Platform.
Stage 2: Strike-Off — Approving the Print and the Hand
Once the shade works, the print takes its turn. A strike-off is a short length that shows the pattern at production scale, including the repeat, the registration, the colour build-up, and the finish. Therefore, a strike-off answers questions a lab dip cannot: does the motif sit where the artist intended, and does the fabric feel right after printing?
Approach the strike-off on a flat surface under a controlled light, and check five points:
- Repeat and registration. Look for gaps, overlaps, or a motif that drifts across the width.
- Colour build-up. Heavy coverage areas often reveal uneven ink penetration before anything else does.
- Sharpness. Blurred edges suggest a screen or machine issue rather than a design issue.
- Hand feel. Printing changes the drape and the surface. Confirm the finish matches the specification.
- Reverse side. For wax-style prints, check how the colour reads on the back, because buyers in several markets inspect both faces.
Colour approval and colour performance are different subjects, and both belong in the file. Our explainer on colour fastness in printed fabrics covers the tests that predict how the approved shade behaves after laundering and sun exposure. In addition, AATCC publishes the standard methods that labs use for these checks, including colourfastness to laundering and colourfastness to crocking, listed on the AATCC standard test methods page.
Stage 3: Bulk — Keeping Production Inside the Approved Window
Bulk approval is where discipline pays. The mill now dyes or prints a full run, and small process variations accumulate: dyebath temperature, chemical dosing, machine speed, fabric tension, and the base cloth itself. Consequently, you should expect some movement, and you should define how much movement you will accept before the run starts. A tolerance you agree during the lab dip, strike-off and bulk sequence costs nothing; the same tolerance argued after shipment costs goodwill.
Practical measures that keep a bulk run inside the window:
- Fix the reference. Keep the signed standard and the approved strike-off in the mill, protected from light and handling.
- Define the tolerance in the contract. State how many shades you will accept and how you will measure the difference.
- Agree the sampling plan. Decide which rolls the mill pulls for shade checking and how the mill records the results.
- Segment the run. Dye or print in planned lots, and keep lot identification on every roll label.
- Review before packing. A shade band review at the end of the run catches a drift while the mill can still correct it.
When a shade dispute reaches a laboratory, both sides need the same starting point. Therefore, retain your approved standard, keep it in a sealed sleeve, and replace it on a fixed cycle instead of using the same faded piece for years.
Why Two People See Different Colours
Colour lives partly in the cloth and partly in the observer, and three factors explain most disputes.
Light source. Fabric that matches under daylight may look clearly different under office or store lighting. This is why laboratories evaluate colour under defined sources. The CIE, which the ISO colour committee lists as a liaison organisation, publishes the lighting and colour systems that these practices build on, and you can browse its work on the CIE website.
Metamerism. Two samples can match under one light and diverge under another, because they reach the same appearance through different chemistry. Metamerism is common when a supplier matches a target with a different dye class, so test any new shade under more than one source before you approve it.
Viewing conditions. Angle, background, surface texture and the size of the sample all shift perception. A sample viewed against a white wall reads differently from the same sample on a dark table.
Standard reference materials reduce the argument. AATCC publishes grey scales for colour change and UV calibration reference fabric, and its testing and standards resources cover these evaluation tools along with standard detergent for laundering tests.
The Approval Record: What to Write Down
Keep one file per order, and keep it current. Include:
- Master standard identification, with the date it was issued and the material it sits on
- Each submission, labelled with its round number and the exact change requested
- The light source and viewing conditions used for every judgement
- The decision, stated as approved, approved with comment, or rejected — plus the reason
- The signer’s name and the date, so responsibility has an owner
- The retained physical samples, stored away from light and humidity
- The tolerance definition that will govern the bulk run
That file solves disputes faster than any discussion, because it records what both sides agreed at a specific moment. A documented colour approval workflow also shortens the next order, since the mill repeats a recorded decision instead of reopening it.
Five Approval Mistakes That Cause Bulk Rejects
- Approving from a screen. Monitors, phones and printers render colour differently, and nobody can verify a shade from a photograph alone.
- Approving under the wrong light. Judging a dip in an office without a defined source produces an approval that fails in the market.
- Requesting changes without direction. “Make it brighter” leaves the colourist guessing; specify the direction and the target.
- Skipping the strike-off. Buyers who approve only a lab dip discover print problems after the run, when correction costs far more.
- Losing the standard. A faded or misplaced reference invalidates every later comparison, and the dispute becomes unwinnable.
Each mistake shares one root cause: the buyer treated approval as a step to clear rather than a record to build. Therefore, slow down at the gate, and the container arrives predictable.
How Weifang Tianhong Runs the Three-Stage Workflow
We treat the three stages as one continuous process rather than three separate transactions. Practically speaking, our team issues a lab dip against your target shade, sends a strike-off once the shade settles, and then runs bulk against the signed standard — and we keep the retained samples so a later question has an answer. For custom work, the same sequence supports your own artwork, and our article on custom wax print design shows how the pattern moves from file to approved fabric.
Because colour approval interacts with fibre choice, our comparison of cotton and polyester wax prints explains how each base cloth takes dye, and our abaya fabric selection guide covers the deep shades that modest-wear buyers demand. You can also review our wax print fabric range, the ultrafine denier microfiber range, and our quality checks on arrival.
FAQ
How many lab dip rounds should I plan for? Plan for more than one. Because the first dip rarely lands exactly on target, a schedule that assumes a single pass tends to slip. Build time into your calendar and give clear directional feedback after each round.
What is the difference between a lab dip and a strike-off? A lab dip settles the shade on a small piece, while a strike-off shows the printed pattern, repeat and finish on a short length. Approve the shade first, then the print.
Should I approve colour from a photograph? No. Screens and printers shift colour, and lighting changes appearance. Use photos to document progress, yet judge and approve against a physical sample under a defined light.
Why does my bulk fabric look different from the approved sample? Production introduces variables that lab work does not: dyebath chemistry, machine speed, tension and base cloth. Define a tolerance in the contract, and check the shade band at the end of the run.
What is metamerism, and why does it matter? Metamerism describes two samples that match under one light yet differ under another. It matters most when a supplier matches your target with a different dye class, so inspect new shades under more than one source.
How long should I keep the approved standard? Keep it for the life of the program, store it in a light-protected sleeve, and replace it on a fixed cycle. A faded reference quietly invalidates every comparison you make against it.
Final Thoughts
Running lab dip, strike-off and bulk as one colour approval workflow protects both sides of a fabric order. Approve the shade, then the print, then the production run, and record each decision with the light, the date and a signature. Moreover, keep the physical standard in good condition, because a colour argument without a reference has no resolution.
Need a shade to review? Contact our trade team with your target colour and base fabric. We will prepare a lab dip or a strike-off, explain the light source we used, and send a free A4 sample so you can judge the fabric before the dyebath starts. You can also read about our production setup on the About page.