The Buyer’s Guide to Fabric Lab Dips and Strike-Offs

A color is never approved on a screen, and it is rarely approved on the first try. In apparel production the color conversation happens twice before bulk fabric is even ordered: once as a lab dip, and once as a strike-off. Buyers who understand what each one proves, how much time each one takes, and what usually goes wrong with each one can cut weeks out of a development calendar. Buyers who treat the two as paperwork tend to discover the real color on their cutting table, when it is far too late to change anything.

This guide walks through the lab dip process and the strike off fabric stage from the buyer’s side of the table: what to specify in the request, how to evaluate the result in a standard light source, how to keep approvals consistent across a multi-color program, and how to build a color approval workflow that does not collapse when a buyer, a mill, or a season changes.

What a Lab Dip Actually Is

A lab dip is a small piece of fabric — usually a swatch of a few square inches — dyed in a laboratory, outside the production line, to a target color. It exists to answer one question: can this mill hit this color on this fabric with a recipe they can later reproduce in bulk? Everything else about the lab dip is secondary to that.

Because it is made on lab equipment with small dye lots and often on a sample piece of greige rather than the actual production roll, a lab dip is a prediction, not a promise. It tests the recipe and the mill’s colorist, not the production dyehouse. That distinction matters when a buyer sees an approved lab dip and assumes the bulk lot will look the same. It usually will, if the mill is competent — but the mechanism that makes it match is a production formula derived from the approved dip, not the dip itself.

• Purpose: confirm a feasible recipe for a target color
• Typical lead time: 5–12 working days per round, plus shipping
• Typical quantity: two to four swatches per color, hand-sized
• What it does not prove: bulk reproducibility, lot consistency, fastness

How the Lab Dip Process Runs, Step by Step

The sequence is predictable, and most delays come from buyers not knowing where they sit in it. A clean round looks like this:

• Step 1 — Color reference: the buyer supplies a target. This can be a Pantone TCX or TPX chip, a physical standard swatch, a previous production lot, or a digital value. Physical references outperform digital ones; a chip travels better than a hex code.
• Step 2 — Recipe development: the mill’s colorist builds a dye formulation using the dyestuff class appropriate to the fiber — reactive for cotton and viscose, disperse for polyester, acid for nylon and wool.
• Step 3 — Lab dyeing: the recipe is applied to small samples, often several variants at different concentrations, to bracket the target.
• Step 4 — Spectrophotometer reading: the mill compares each variant to the reference and produces a numerical difference report.
• Step 5 — Submission: the closest one to three variants are sent to the buyer, usually labeled A, B, C.
• Step 6 — Buyer evaluation: the buyer views the dips under specified lighting, decides, and comments — approve, approve with a shade direction (“a touch warmer”), or reject.

Each loop through steps 2–6 costs roughly one to two weeks including courier time. A program with eight colors and two rounds per color — normal, not wasteful — needs a realistic six to eight weeks of calendar time before bulk fabric can be booked. Building that into the development calendar is the difference between an on-time launch and a rushed one.

What to Put in the Lab Dip Request

The quality of the dip is bounded by the quality of the request. A one-line email asking for “navy” will produce a technically compliant, commercially useless result. A request that carries the following fields tends to come back correct on the first or second round.

• Color reference: chip number plus a physical standard, with a note on which one governs if they disagree
• Fabric specification: composition, yarn count, knit or weave structure, weight in gsm, and finish (peached, brushed, compacted)
• Lighting condition: which illuminant is primary — D65 daylight, TL84 store light, or a specified in-house condition
• Pass/fail tolerance: the color difference limit the buyer will accept, stated upfront rather than argued later
• Metamerism expectation: whether the color must match under more than one light source
• Fastness requirements: wash, light, perspiration, and crocking standards that the eventual production must pass
• Quantity and deadline: how many swatches, and the date by which the buyer needs them in hand — not the date they should be sent

Two of those fields cause most of the disputes. Stating the tolerance upfront avoids the classic standoff where the mill says “within standard” and the buyer says “visibly different.” Stating the lighting condition avoids the second classic: an approval given under office lighting that fails in a retail store.

Evaluating a Lab Dip Without Guesswork

Visual assessment still governs most approvals in apparel, but it should be structured. The practical method:

• View the dip and the standard side by side, edges touching, never overlapping.
• Use a light booth set to the specified illuminant, with the rest of the room dark.
• Check under at least one secondary illuminant, usually a warm store light, to catch metamerism.
• Read the dip from three angles to spot directional shade shifts on knits and pile fabrics.
• Record the numerical difference alongside the visual verdict — the number does not decide, but it documents.

Black, navy, and deep reds deserve extra scrutiny. Dark shades hide small differences visually while amplifying them in production, and they are the shades most likely to shift when the mill scales from a lab beaker to a production kettle. Whites are the mirror problem: optical brighteners make whites look identical on a swatch and divergent on a garment, especially after home laundering.

What a Strike-Off Is, and Why It Is Not a Lab Dip

A strike off fabric sample shows how a design — print, pattern, or surface effect — looks on the actual fabric, in the actual process, at roughly actual scale. A lab dip tests a color recipe on a plain ground. A strike-off tests a whole execution: engraving depth, ink or paste viscosity, registration, coverage, hand feel after curing, and how the artwork interacts with the fabric structure.

If you are approving a solid dyed fabric, you need a lab dip. If you are approving a print, you need a strike-off, plus a lab dip for any ground color underneath it. Programs that print on dyed grounds need both, and the two approvals should reference each other — approving a print on an unapproved ground is a common and expensive mistake.

• Purpose: confirm print execution, scale, registration and hand
• Typical lead time: 7–15 working days per round, longer for rotary screen engraving
• Typical format: a length of fabric or a panel large enough to show repeat and placement
• What it does not prove: bulk registration consistency, long-run color drift, final hand after garment wash

Reading a Strike-Off Critically

Strike-offs flatter the design. They are produced on clean equipment, often by the most experienced operator, at a controlled pace. The buyer’s job is to look past the flattery.

• Scale and repeat: measure the repeat against the spec and against a garment pattern piece. A repeat that looks balanced on the flat can land awkwardly on a shoulder seam or a side panel.
• Registration: check for haloing between colors and drift across the width. Ask whether the strike-off was run on production equipment or a sample machine.
• Coverage and penetration: look at the back of the fabric. Incomplete penetration shows up as a chalky hand and as cracking after washing.
• Hand and drape: compare against the unprinted ground. Heavy ink coverage stiffens stretch fabrics and changes how they recover.
• Color: evaluate print colors the same way as a dip — light booth, secondary illuminant, recorded numerical difference.
• Fabric behavior after finishing: ask for a washed or finished strike-off if the garment will be garment-dyed, washed, or heavily finished.

Building a Color Approval Workflow That Holds

Single approvals are easy. A program with twelve colors, three factories, and a buyer change in the middle is where color programs fall apart. A few structural habits keep them stable.

• Keep physical standards, not just files. Every approved color should exist as a signed, dated, physically retained standard — one at the mill, one at the factory, one with the buyer. A digital folder alone will not settle a dispute.
• Freeze standards before bulk booking. Once a dip is approved, the mill derives a production formula from it. Changing the standard after bulk dyeing starts means reworking a lot, not editing a file.
• Approve by round, not by mood. Record each submission — date received, verdict, comment direction, and the standard version it was compared against. Two seasons later this log is the only way to know what “the approved navy” means.
• Limit the number of rounds contractually. Two or three rounds is standard. Unlimited rounds signals an unclear standard on the buyer’s side and invites slow submissions.
• Name a single approver. Color by committee produces either paralysis or two incompatible standards.

Common Failure Modes and How to Avoid Them

Most color problems are predictable, which means most are preventable.

• Approving on a swatch of the wrong ground. A dip on a similar but different fabric will not transfer. Insist the dip is made on the specified ground.
• Ignoring metamerism. A color that matches under D65 but shifts under store lighting will generate returns. Ask for a secondary-illuminant check on every approval.
• Treating fastness as a separate issue. Fastness is set by dyestuff selection, which happens at recipe stage. If the dip is approved on a recipe that cannot meet the wash standard, the fastness failure is already baked in.
• Shipping dips with weak packaging. Unprotected swatches pick up marks and travel dirty, and a soiled dip cannot be judged. Individual sleeves and a rigid envelope cost little.
• Letting the mill self-approve. The mill’s spectrophotometer is a tool, not a verdict. Buyer approval should be an explicit event with a date.
• Batch-approving at the end. Twelve colors reviewed in one sitting, after a two-week courier delay, compresses the schedule into the most expensive part of the calendar — the part right before bulk booking.

Typical Timelines and What to Plan For

Working from a realistic calendar beats working from optimism. A reasonable planning envelope for a mid-size program:

• Solid colors, single ground: one round of 7–10 working days for 70% of colors; a second round for the remainder
• Difficult shades (black, navy, brights, whites): budget two to three rounds by default
• Prints: 10–15 working days per strike-off round, longer if screens must be engraved
• Courier time: three to five working days each way for international submissions, often the largest single block
• Total from brief to approved standard: four to six weeks for a clean solid program, six to ten weeks for a print-heavy one

Digital submission of the numerical report alongside the physical swatch can compress the loop meaningfully: the buyer can pre-screen against the tolerance and reserve physical judgment for the closest candidates. It does not replace the physical approval, but it makes the courier leg count.

Color Approval as a Procurement Discipline

The buyers who get consistent color treat approval as a documented process rather than a creative judgment call. They specify the ground fabric, the illuminant, and the tolerance before a single dip is dyed. They keep physical standards in three locations and a log of every round. They expect two rounds, plan for three on the hard shades, and never let the approval calendar compress into the weeks before bulk booking.

None of that is exotic. It is administration — but it is administration that decides whether the bulk lot matches the marketing photography, whether the second production run matches the first, and whether the buyer can prove any of it a year later when a distributor asks for the approved standard. Lab dips and strike-offs are small, cheap documents. The decisions they lock in are neither small nor cheap.