04 DYE CLASSES · 06 PRINTING METHODS · ISO / AATCC COLORFASTNESS
Dye chemistry, printing, and the science of color that lasts.
Reactive, disperse, acid, vat — and the printing methods, fastness tests, and finishing chemistry that decide whether color stays or walks out in the first wash.
What’s in this section
Dye classes
Which dye bonds to which fiber — reactive for cellulose, disperse for polyester, acid for protein, vat for the deepest indigos and sulfur blacks.
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Printing methods
Screen, roller, digital inkjet, block, discharge, resist — how the pattern gets onto the fabric and the trade-offs of each method.
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Colorfastness testing
Wash, light, rub (crock), perspiration — the standard tests that determine whether a color is commercial-grade or showroom-only.
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Common dyeing defects
Uneven shade, barré, listing, poor rubbing fastness — what causes each, how to spot it on the line, and how to fix the recipe.
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Featured reading
Can you dye ivory fabric to white — and white to ivory?
The chemistry of optical brighteners, fluorescent whitening agents, and why going whiter than the original fabric is harder than it looks.
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02
Reactive dyes on cotton: the covalent bond explained
Why reactive dyes are the workhorse of cellulose coloration — and the salt/alkali exhaustion process that makes the bond permanent.
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03
Disperse dyes on polyester: high-temperature coloration
Why polyester needs 130 °C and a carrier to take color — the solubility, particle size, and fiber swelling that drive the process.
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Why engineers trust these guides
Dyeing is half chemistry, half recipe — our guides publish the chemistry, name the standard (ISO 105, AATCC 8/61/132), and tell you which process variable to actually move when something goes wrong on the floor.
Frequently asked questions
Which dye class is right for my fiber?
Cotton and other cellulosics → reactive (or direct for low-cost). Wool, silk, nylon → acid. Polyester and other synthetics → disperse. Acrylic → cationic. Deep indigos and sulfur blacks → vat. The dye is chosen to match the fiber’s functional groups and the color-fastness target.
What’s the difference between reactive and direct dye?
Direct dyes adsorb onto cellulose with weak intermolecular forces — they’re cheap but wash out over time. Reactive dyes form a covalent bond with cellulose hydroxyl groups — the bond is permanent under home laundering, which is why reactive is the industry standard for cotton apparel.
Why does some color bleed in the wash?
Bleeding is dye that wasn’t fully fixed or wasn’t thoroughly washed off after fixation. Reactive dyes need a hot post-soaping rinse to remove hydrolysed (unreacted) dye; skipping that step leaves dye that will bleed into the next wash.
What is crocking?
Crocking is color transferring by rubbing — the standard test is AATCC 8 (or ISO 105-X12), which uses a crock cloth rubbed against the fabric under controlled pressure. The stain on the cloth is rated 1–5; commercial-grade fabric should rate 4 or higher dry and wet.
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12+ DYEING & PRINTING GUIDES · ISO 105 / AATCC REFERENCED