How We Ensure Colorfastness in Knitted Garments
A look inside the testing bench: how every dye lot is measured, rated, and signed off before it becomes a garment on your rack.
PASS THRESHOLD
Colorfastness is the single most common cause of buyer complaints in knitwear — a hem that bleeds onto a white sock, a collar that fades three washes in, a swatch that transfers ink onto the skin. None of it is random. It’s the direct, measurable result of how a dye was chosen, applied, fixed, and tested before the fabric ever left the mill. Here’s exactly how we control for it.
01 — The StandardWhy We Test Against a Gray Scale, Not a Guess
Every colorfastness result we report is scored against the AATCC Gray Scale, the industry-standard reference shown above. A swatch is washed, rubbed, or exposed to light, then compared side-by-side against the scale to assign a numeric rating from 1 (severe color change or staining) to 5 (no visible change). This isn’t a subjective call — it’s a calibrated visual comparison performed under standardized lighting, the same method used across the global supply chain so a “4” means the same thing whether the test was run in our lab or yours.
Our internal pass threshold for knitwear intended for apparel is a rating of 4 or higher on washing and crocking, and 3 or higher on light exposure for garment-dyed pieces. Anything below that gets flagged before it reaches cutting, not after it reaches your warehouse.
02 — The BenchThe Four Tests Every Dye Lot Goes Through
Before a dye lot is approved for bulk production, a lab sample runs through a fixed battery of tests. Each one simulates a different way a garment meets the real world.
Wash Fastness
ISO 105-C06Swatches are laundered under controlled detergent, temperature, and agitation cycles, then rated for both color change and staining onto adjacent white fabric.
Light Fastness
ISO 105-B02Swatches sit under a xenon-arc lamp calibrated to simulate sunlight exposure over graded time intervals, then are compared to unexposed control samples for fade.
Crocking (Rubbing)
ISO 105-X12A crockmeter rubs a standardized white test cloth against the fabric in both dry and wet states, checking whether surface dye transfers under friction — the cause of dye rubbing off onto skin or upholstery.
Perspiration & Water
ISO 105-E04 / E01Swatches are saturated with acidic and alkaline synthetic perspiration solutions (and separately, plain water), then incubated under pressure to check for bleeding — critical for activewear and next-to-skin knits.
03 — Knitwear SpecificsWhat’s Different About Testing Knits
Knitted fabric behaves differently from woven fabric under the same tests, mostly because of structure and stretch. A few things we watch for specifically in knits:
Open loop structures absorb and release dye differently
The looped structure of knit fabric has more surface area and open space than a tight weave, so dye can sit closer to the surface in some stitch patterns. Ribs, cables, and other three-dimensional stitches are spot-tested separately from plain jersey sections of the same garment, since fastness can vary across a single piece.
Crocking tests are repeated on stretched fabric
Because knits stretch under wear, we run an additional crocking pass with the swatch held under tension, simulating a sleeve cuff or waistband under real stress — a step not typically required for stable woven fabric.
Poly-cotton knits are tested fiber by fiber
A cotton-polyester knit dyed with both reactive and disperse dye classes is tested for staining onto both cotton and polyester reference cloths independently, since a shade that passes on one fiber can still stain the other.
Sublimation checks for any synthetic content
Any knit containing polyester goes through an additional heat-press sublimation check, since disperse dyes can migrate under high heat — a real risk during steam pressing, finishing, or hot transit conditions.
What this means for a repeat order
Every approved dye lot is kept on file with its full test record. When you reorder the same colorway, we pull the original lab dip and results rather than re-guessing the recipe — so shade and fastness stay consistent from your first production run to your fifth.
04 — By FiberHow Fastness Expectations Shift by Fiber Content
Fastness isn’t a single number we hold every fabric to — reasonable targets differ by fiber and dye class, and we set thresholds accordingly.
| Fiber / Dye Class | Wash Fastness Target | Common Risk |
|---|---|---|
| Cotton — reactive dye | Grade 4–5 | Unfixed dye rinsing off in first few washes |
| Cotton — vat dye | Grade 4–5 | Lower shade brightness vs. reactive alternatives |
| Polyester — disperse dye | Grade 4–5 | Sublimation/color transfer under heat |
| Cotton/poly blend | Grade 4 (both fibers) | Shade mismatch between the two dye stages |
Every lot, tested before it’s cut
Colorfastness reports are generated per dye lot and available on request for any order — so you can see the gray scale rating behind your garment before it ships, not after it’s returned.