Lab Dip Explained: Why Color Approval Takes Multiple Rounds
A lab dip is a small, hand-dyed swatch of your actual fabric, dyed to match a target color before bulk production starts. It exists because a Pantone code, a screen color, and a physical dye result are three different things, and the only way to know what your fabric will actually look like is to dye a piece of it and hold it in your hand. Two to three rounds is normal. One round is the exception, not the rule.
Why the First Lab Dip Is Rarely Approved
A Pantone or digital color code was built for ink on coated paper. It was never built for dye absorbed into a fiber. When a dyehouse mixes a recipe to match that code, they're translating between two physically different color systems, and the first attempt is a calculated estimate, not a guarantee.
Fiber content changes the result on its own. 100% cotton, a cotton-poly blend, and 100% polyester all absorb the same dye recipe differently, because each fiber has a different chemical structure and dye affinity. A recipe tuned for cotton jersey will not produce the same shade on a poly-cotton blend, even with an identical target code.
The fabric's own base color matters too. Undyed (greige) fabric isn't pure white — it carries a slight natural tone depending on the cotton source and any pre-treatment. That base tone shifts the final dyed color slightly, which is one more reason a swatch has to be dyed on your actual production fabric, not a generic sample.
What Actually Happens Between Rounds
Round 1: the dyehouse mixes a recipe from the target code and dyes a small swatch, usually 30x30cm, on your actual fabric base.
Round 2: the buyer compares the swatch against the target, under consistent lighting, and flags the direction of the shift — too warm, too dark, too grey, too saturated. The dyehouse adjusts the recipe's specific dye components in that direction and redyes.
Round 3, if needed: a final fine-tuning pass, usually a small percentage adjustment to one or two dye components rather than a full recipe rebuild. By this point the recipe is close, and the remaining gap is usually visible only in direct side-by-side comparison, not to a casual eye.
The Approval Mistake That Costs the Most Time
Approving a lab dip by looking at it on a phone screen, or under office fluorescent light, then discovering it looks wrong in daylight or under a shop's LED lighting, is the single most common reason a color gets rejected after bulk dyeing has already started — at which point it's too late to fix cheaply.
This effect has a name: metamerism — two colors that appear to match under one light source and visibly don't match under another. Always check a physical lab dip swatch under at least two light sources (daylight near a window, and a warm indoor light) before signing off. A screen photo of a lab dip is not an approval-grade reference, under any circumstances.
Lab Dip vs Bulk Dyeing: Why a Match at This Stage Isn't a Guarantee
| Factor | Lab Dip | Bulk Dyeing |
|---|---|---|
| Batch size | 30x30cm swatch | Hundreds of kilos of fabric |
| Dyeing method | Lab-scale beaker dyeing | Industrial dyeing machine |
| Temperature/time control | Precisely controlled, small volume | Harder to control uniformly at scale |
| Typical variance from lab dip | — | Small shade shift is normal and allowed within an agreed tolerance |
This is also why serious buyers request a bulk dip — a small pre-production dye run at close to real production scale — for large or color-critical orders, rather than trusting the lab dip result to hold perfectly at full volume. It costs a little extra time upfront and removes almost all of the risk of a bulk-dyeing surprise.
How to Get Your Color Approved Faster
Give a physical reference alongside the Pantone code whenever you have one — an existing garment, a fabric swatch, anything physical. A dyehouse matching a physical swatch typically needs fewer rounds than one matching a digital code alone.
State your tolerance up front. If your brand can accept a very close match rather than an exact one, say so — chasing a perfect match on a fiber-dye combination that resists it can add rounds for a difference few customers would ever notice on the finished garment.
Approve in writing, with a photo taken in consistent lighting, not a verbal "looks good." This single habit prevents the most expensive kind of dispute — a bulk dye lot that gets rejected after the fact because the original approval was never clearly documented.
Lab Dip FAQ
The first round is normally included in sampling cost. Most factories charge a small fee per additional round after the second, since each round uses dye, lab time, and courier cost. Get this stated in writing before sampling starts, not after the third round arrives.
Only if you're using an existing, already-dyed stock fabric with a fixed color. For any custom or Pantone-matched color on new fabric, skipping it means the bulk dye lot is your only chance to get the color right, with no correction possible once it's dyed.
Different fibers absorb dye differently. A color that reads accurately on a coated paper swatch can shift several shades once dyed into cotton, polyester, or a blend — which is exactly why a physical lab dip on your actual fabric matters more than the code itself.
Each round typically takes a few days including courier time if you're approving remotely. Two to three rounds is the realistic range for most custom colors, so budget roughly a week to ten days for color approval before bulk dyeing can begin.
Most buyers and factories work within an agreed grey-scale rating (a standard textile method for scoring color difference) rather than requiring a pixel-perfect match, since dye lots always carry some natural variance. Ask your factory what tolerance they work to before production starts, so both sides are approving against the same standard.
Need a color matched and approved before your next production run? SDF Clothing runs in-house lab dip and bulk dip services on your actual fabric, with documented approval at every round.
Start a Lab Dip Request ?Once your color is approved, the next place buyers get caught out is shade variation between dye lots. Read Shade Variation Explained to understand why it happens and what tolerance is normal.
Choosing the right fabric weight before you get to color? See our Fabric GSM Explained guide.