Have you ever wondered why paint color chips look so different once you get them home? Or maybe it was siding, tile or carpeting samples that seemed to shift color so dramatically that you were convinced you must have picked up the wrong sample and brought it home by mistake.

choosing wall colors

They look so different here at home, I wonder why?

Many color consultants would reach for the color term metamerism (me ‘ta merizm) to explain what happened. Which is close, but not exactly on the money. Metamerism is often incorrectly defined as a phenomenon that occurs when a color changes when viewed in different light sources. Technically that’s not correct.

Change the light, change the color. Image Source: Flickr user Johannes Ahlmann

Rather, metamerism is specifically defined as a phenomenon that occurs between TWO samples, not just one color. In other words, two color samples when compared appear to match under one light source, but they don’t match under a different light source. For example, the two samples match in the store’s fluorescent lighting but do not match outside in sunlight.

If you have made color choices in a store setting that you ended up regretting, it doesn’t really matter what it’s called.  All you know is you have spent time and/or money on something that turned out to be the wrong color.

What happened is actually not as involved as metamerism. It’s simply a matter of when the light changes, the color changes. The easiest way to explain it is every color reflects and absorbs light. And, every source of light shines with wavelengths of different colors. Let’s use paint color chips as an example going forward.

Light and ColorThere is a unique bundle of wavelengths of daylight beaming in from windows and doors as well as light bouncing around the room from artificial light fixtures.  Known as spectral power distribution (SPD), those sources of light, natural and artificial, define the amount and quality of light in interior rooms.

Paint colors have a unique and varied bundle of wavelengths too but instead of beaming wavelengths, they are reflected wavelengths.

A paint color can only reflect the wavelengths that shine on it — makes sense, right? Therefore, if the light source is nicely balanced and shines wavelengths from almost all the colors in the visible spectrum, then your paint color has a lot to work with. It can respond to the light and reflect all the wavelengths it has. Which means in a reasonably balanced quality of light, your paint color is going to look the way it was intended to look.

warm light

Trouble happens when the light source is not balanced. Meaning it shines a bunch of wavelengths from just one or two areas of the visible spectrum. It might shine more wavelengths from the yellow and red areas, for example. Your typical light bulb, called tungsten or incandescent, is like that; it looks so warm and cozy because it beams a lot of yellow and red wavelengths.

fluorescent lights

Many types of fluorescent fixtures shine more wavelengths from the green and blue areas of the visible spectrum and that is what makes a room look kind of cold and institutional.

That’s what one of my color expert colleagues recently experienced when she was shopping at a home improvement store. Of course, being a color expert she happened to have a sheet of Pantone Lighting Indicator stickers with her.Pantone Lighting IndicatorsThese stickers are handy for lots of things. Actually, they’re a great example of using tools based on color science and applying it to everyday color decisions. Or as I like to call it, “practical application of extraordinary color expertise”.


Photo Credit: Karen Collins

How these stickers work is very simple. You can choose from D50 or D65 stickers. D50 is good for graphics and printing. D65 is great for textiles, paint colors, architectural color design in general.

Illuminant D50

Illuminant D65

D65 and D50 are illuminants. Illuminant is a color science way of categorizing the appearance of different light sources and labeling them so you know what wavelengths in the visible spectrum they will produce. Here’s the crazy thing, D65 and D50 aren’t physical light bulbs. They’re mathematical lighting scenarios. In other words, average qualities of daylight have been quantified – transformed into numbers. Transforming a quality of light into numbers means we can use equations to help us understand how light works and how color responds to light.

That’s why these stickers are a great example of color tools based on science. The D65 stickers were created to respond to a D65 quality of light. So, if the stickers show two colors, you know the lighting conditions are somehow unbalanced and not ideal for color assessment tasks. By the way, a D65 quality of light strives to mimic daylight around noontime.  Let me tell you why D65 is a good illuminant to use for architectural color decisions.

In non-technical terms, D65 is a comfy quality of light that our eyes adjust to easily. That’s the short answer. Going a little deeper, I can tell you more about how that works:

The D65 illuminant is essentially about adaptation – adaptation is how quickly and easily our eyes adjust to a change in lighting conditions.  A movie theater is a good example; you go to an afternoon matinee and come out of a darkened movie theater into the daylight and your eyes have to adapt to the new lighting conditions.

The D65 illuminant simulates a quantity and quality of daylight to which our eyes easily adapts. It is slightly cooler maybe bluer than direct sunlight whereas direct sunlight looks orange or pale amber.

adaptationSimply put, D65 is a standard illuminant for architectural color assessment because it works well with our vision system.

The D50 illuminant is okay to use too, it’s just D65 is a better fit for making human supportive color decisions for the built environment.

Now, what if I told you there was a way to know what every paint color out there was intended to look like; what its “true color” looks like in a D65 quality of light? In addition, what if I told you once you know how to get that information, you can use it to navigate to the right paint color choices every single time – and fast? Sounds amazing, doesn’t it? Well, it is and I can teach you how to do all this and more if you sign up for my Camp Chroma color training courses.

In summary, a color shifting in appearance is simply a matter of change the light change the color. The more unbalanced the light source, the more dramatic the shift will be. It’s not metamerism unless you’re comparing TWO color samples.

Pantone makes handy stickers that will alert you when you’re in poor, unbalanced lighting conditions for making color decisions – D65 is best for architectural color and design. You can buy the stickers here: https://www.pantone.com/lighting-indicator-stickers-d65

If you want to learn more about the practical application of extraordinary color expertise, Camp Chroma is the only resource that offers a colorimetry (color science) based curriculum. You can read what recent graduates had to say about the course here: Camp Chroma Testimonials


  1. Fabulous post! Would love to hear how you’ve corrected such unbalanced lighting conditions. I’ve found that the low-natural-light, fluorescent-lit environments of some newer homes are among the most challenging. It seems like everything looks muddy and washed out in such spaces.

    • Hi Juli,

      I’m a fan of full spectrum paint colors. They come locked and loaded to respond to whatever quality and quantity of light there is to work with. Most of the time, that’s the answer. Whether it’s C2, Ellen Kennon or Benjamin Moore’s Color Stories, there is something in there for everyone and every lighting situation.

      You can also play the formula game a little. As you well know, I don’t believe there is any useful information to be had by looking at the list of colorants that went in the can. The ‘laws of substance uncertainty’ guarantee there is no possible way to know what’s going to happen when you mix one or more colorants into a can of base; you have to mix the color, paint a sample, let it dry and then evaluate what happened in the can.

      However, I have one exception to my rule about formulas and that is black.

      It can be worthwhile to ferret out regular paint colors from regular fandecks that do not have black in the formula. Or, ask the paint store colorists if they *can* mix a custom color for you using alternative colorants instead of black.

      As always, you have to be very cautious with custom mixed colors because they are unmeasured. They have no spectral data that indicates LRV and no information about lightfastness and stability for use exterior. You essentially know nothing about how that color will behave and hold up over time.

      So, tweak and custom mix colors with extreme caution.

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