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Fading of a Single Colorant
Enter the parameters for the planned light exposure and then click the Compute Fading button.
Calculated colour values
|Original||Current||Future, with all UV removed||Future, with UV (equiv. to daylight through glass)|
(251, 0, 72)
(251, 0, 72)
(255, 32, 76)
(255, 41, 78)
|ΔE (from original)||0||0.0||2.78||4.21|
|ΔE (from current)||N/A||0||2.78||4.21|
- A value of ΔE=1.6 is approximately equal to a 'just noticeable fade'.
- The dose of Mlx∙h in the current color is an estimated dose causing prior fade, assuming no UV. With UV, it would be estimated to be 0 Mlx∙h.
Colorant (RED Alizarin; paint) notes
Used in watercolours, oil paints, and acrylics. Invented in 1868, and replaced the natural pigment madder, which contains alizarin plus purpurin. Tends towards slight blue tone.
FADE: Colour Index gives alizarin lake, full tint, ISO 7; ½ tint, ISO 5. Feller et al (1984) report alizarin lake on paper as ISO 4-5. Calculator uses ISO 4.5. BENEFITS OF UV REMOVAL. Feller et al (1984) state the measured benefit for alizarin lake is "some." This suggests no more than x1.5. A cautious fit to McLaren’s (1956) data on the Blue Wools and 117 dyes suggests a typical benefit of UV removal of x3.2 for ISO 4.5 dyes. Calculator uses x1.5 for all alizarin and madder colorants.
- Please refer to the legal disclaimer before using the light damage calculator tool.