Spectral Signature
The graphical plot of the percentage of light reflected by a material at each wavelength across the visible spectrum represents the color footprint of a textile. By analyzing the reflectance curve of a fabric sample, a dyehouse can determine the exact mix of dyes required to replicate it. This data remains constant regardless of the light source or the human observer’s vision.
Graphical Analysis
The horizontal axis of the plot represents wavelengths from four hundred to seven hundred nanometers, while the vertical axis represents the reflectance from zero to one hundred percent. A bright yellow cotton fabric will produce a line that sits low in the blue region and rises sharply to a high plateau in the red and green wavelengths. Conversely, a deep navy fabric will have a line that peaks in the blue region and remains very low across the rest of the spectrum.
Spectrophotometers measure this profile by dividing the reflected light from the sample by the light reflected from a calibrated white tile.
Recipe Matching
Computer color matching software uses these plotted lines to calculate dye recipes that match the target sample under all illuminants. This process prevents metamerism, where a sewn garment appears to change color when moved from natural daylight to store lighting.
Surface Restrictions
The measured profile is affected by fabric texture, fiber cross-section, and the presence of moisture. Wet fabric absorbs more light, which lowers the entire plotted line and makes the color appear darker and more saturated.
