Color Stability

a guest post by Lisa J. Reed, Lighting Designer

Color Stability

Have you ever noticed that over time, a nice white light can turn pink or blue or green? Have you noticed a difference in colors when you install a new lamp next to an old one? What you are seeing could be color shift, and although some are worse than others, all sources do it to some degree.

There are applications where color shift is very problematic, and other places where it may be unimportant. Consider a wall wash application where multiple lights are aimed at the same wall, all in a row. These need to maintain the same color to keep an evenly washed wall from becoming a pastel rainbow of stripes. Retail applications or museum applications require more consistency in their lamp colors. Street lighting applications can get by with less precision.

Why are some of your lights pink, yellow, green, or bluish? Let’s look at the main offenders.

  1. Metal Halide
    Metal halide sources are notorious color-shifters. It happens because the chemistry within the lamp changes as gases migrate through the arc-tube wall over time. One way to alleviate this is to use the same brand, installed in the same orientation, (base up, base down, horizontal) all at the same time. Remember to group relamp, too, for best results.
  2. Fluorescent
    Fluorescent lamps can shift in color over time as well. But the fluorescent shift isn't as significant, and it is less often critical because of the types of applications where fluorescent lamps are used. It may become unsightly in cove lighting or wall grazing, in which cases group relamping should be employed to maintain consistent color.
  3. LED
    The consistency of color over time is definitely a factor in LED fixtures. Read the latest DOE report on Color Stability. The challenge with stability in LED products is that the quality varies widely from manufacturer to manufacturer. When color stability is important, you should work with the manufacturer to get a color warranty.

Initial color consistency between sources is an altogether different cause of mismatched lighting, but color instability can be a more elusive challenge, since it happens slowly over time. In critical applications, be aware of your light source and its ability to maintain color stability.

These variations in color can offend some people more than others. How good are you at recognizing color variations? Just for fun, take this color test, and send us a comment with your score! (I got an 8.)

Lisa J Reed photo - Lighting Blog

Lisa J. Reed has been attracted to lighting (like a moth to a flame) for 20+ years. She is the Founding Principal at Envision Lighting Design, LLC in St. Louis, where she designs, teaches, and writes about architectural lighting.


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