The Substrate Problem — Why the Same Color Looks Different on Cotton, Polyester, and Silk
Different fibers absorb dye differently because of their molecular structure — specifically the ratio of amorphous (loose, dye-accessible) regions to crystalline (tightly packed) regions — along with pH sensitivity and surface reflectance.
On the same dyeing condition, the color depth (measured as K/S) can vary dramatically across fibers:
- Wool can produce a much deeper color depth K/S = 4.4 because it has more amorphous regions.
- Silk reaches roughly K/S = 1.42.
- Cotton reaches roughly K/S = 0.93.
Temperature matters just as much. Polyester dyed at 130°C can actually produce lower color depth than at 100°C, because the dye begins to decompose at the higher temperature.
The takeaway: the same Pantone reference applied to different fabrics will not visually match. This is physics, not a defect.