Color Fastness Prediction Calculator

Dye Type dominates all four fastness ratings in this model -- wash, light, dry rub, and wet rub all move more when you change the dye class than when you change the fiber it's applied to. That tracks real dye chemistry: a dye class is engineered around how it bonds to fiber (reactive dyes form covalent bonds with cellulose, for instance), and that bonding mechanism is a bigger factor in durability than which specific fiber it's bonded to.

Vat dyes are applied in a soluble reduced form and then oxidized back into an insoluble pigment once inside the fiber, which leaves very little unbound dye sitting on the surface to transfer onto another fabric through friction. That's why this calculator boosts both Dry Rub Fastness and Wet Rub Fastness specifically for Vat dye selections, separate from its already-strong wash and light fastness scores.

Not uniformly -- deeper shades in this model trade a little wash fastness for better light fastness, since a higher dye concentration means more pigment available to absorb UV before visible fading sets in. The trade-off runs the other way for pale shades, which hold up slightly better to washing but fade under light exposure faster.

Less than dye choice does across this calculator's ranges, but for Wash Fastness and Light Fastness it isn't negligible -- the same dye class can still land several tenths of a fastness point apart depending on the fiber, since not every dye-fiber pairing is chemically ideal (a reactive dye, for example, is formulated for cellulose fibers like cotton and performs differently on protein fibers like wool or silk). Dry Rub and Wet Rub Fastness are the exception -- this model computes both from Dye Type and Shade Depth only, so fiber choice has exactly zero effect on either rub-fastness output.

Yes, and independently of the dye/fiber pairing modeled here. A soaping-off or cationic fixative aftertreatment after dyeing removes or locks down surface-bound dye that hasn't fully bonded, which measurably improves both wash and rub fastness on the same dye/fiber combination. Washing hotter than the fabric's care recommendation has the opposite effect -- it accelerates dye bleed regardless of how favorably the dye class and fiber are matched. Neither variable is an input here, so treat the ratings above as a best case assuming standard processing and care.