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Is there a blue red color?

Is there a blue red color?

Unfortunately, there is no such thing as a “blue red” color. Here is a 4000 word article explaining why:

The idea of a “blue red” color seems contradictory since blue and red are opposite colors on the color wheel. However, the question arises whether mixing the two could possibly create a new hybrid color. In the following article, we will analyze the properties of blue, red and purple (as a mix of blue and red) to determine if a true “blue red” color can exist.

The Nature of Color

To understand if blue and red can mix to form a new color, we first need to understand how color works.

Color originates from light. Sunlight appears white to our eyes, but it is actually composed of a spectrum of different colored wavelengths of light. When light hits an object, certain wavelengths are absorbed while others are reflected. The wavelengths that are reflected determine what color our eyes perceive the object to be.

For example, a tomato appears red because it absorbs most wavelengths of light except for red. It reflects red wavelengths into our eyes, causing us to see the tomato as red.

The visible spectrum of light that humans can see ranges from violet (shorter wavelengths) to red (longer wavelengths). The three primary colors are red, green and blue. By mixing different amounts of these three colors, we can create all the other colors that we perceive.

This is the basis for computer and TV screens, which use tiny red, green and blue (RGB) light pixels to display colors. By varying the brightness of each RGB pixel, screens can fool our eyes into seeing millions of blended hues.

So to recap, color comes from light, and depends on which wavelengths are reflected versus absorbed. This brings us back to the original question – can blue and red mix to make a new color?

The Nature of Blue and Red

Blue and red are on opposite sides of the color spectrum. Blue has a short wavelength, while red has a long wavelength.

When it comes to light, blue and red maintain their separate identities. If you shine a blue and a red light beam onto the same spot, you will continue to see separate red and blue colors; they do not merge to become a new color.

However, things get more interesting when dealing with pigments and dyes. Pigments absorb certain wavelengths to produce color. Unlike pure light, pigment molecules can blend together to produce new hues. This is the basis for mixing paint colors.

So in theory, a “blue red” color could potentially be created by finding pigments that reflect both blue and red wavelengths. The result might be a shade of purple or magenta. But could the pigments ever mix perfectly to maintain two distinct wavelengths as a true blue-red?

The Nature of Purple

To evaluate if a true blue-red color is possible, it helps to first examine purple. Purple sits between blue and red on the color wheel.

There are a few ways to make purple:

Method Result
Mixing red and blue light Appears white or light gray
Overlapping red and blue pigments Subtractive mixing produces purple
Single pigment reflecting blue and red True purple, with blue and red wavelengths

Mixing red and blue light does not make purple, since the two wavelengths simply pass through each other. However, with pigments, the blue absorbs the red while the red absorbs the blue. What remains reflected to our eyes is a shade of purple, from the mixture of the two wavelengths.

But there is yet another way to make purple – via a pigment that naturally reflects both blue and red wavelengths. This optical mixing creates a “true” purple color.

So in theory, if a pigment could selectively reflect both blue and red wavelengths, it could produce a true blue-red color. But does such a pigment exist in nature?

Natural Blue-Red Pigments

There are few examples of natural pigments that reflect both blue and red wavelengths. Most purple-hued pigments are mixes of separate blue and red compounds rather than a unified blue-red pigment.

Some sea organisms display an extremely bright, unnatural purple-blue color. This comes from brominated phenols and other bioaccumulated organic chemicals that absorb green/yellow light, leaving only blue and red to reflect. While spectacular, these creatures’ colors are really just a purple created by complemenatry blue and red wavelengths.

A class of protein called cryptochromes, found in plants and animals, exhibits a natural blue-red pigmentation when purified and crystallized. The cryptochromes contain a flavin core that reflects dual blue and red wavelengths when stimulated. However, this occurs only under very specific laboratory conditions. In nature, cryptochromes appear colorless or pale yellow.

In general, blue-red colors are rarely found among natural pigments. Complex organic molecules with broad, dual absorption/reflection peaks at opposite ends of the visible spectrum are biologically difficult to produce through evolution. Most organisms simply use a mix of separate blue and red pigments to create purple hues when needed.

So while possible in theory, true blue-red pigments remain elusive. There are few if any examples among the palette of natural pigmentation.

Artificial Blue-Red Colors

If nature struggles to create a blue-red pigment, can human engineering and chemistry succeed?

Modern synthetic dyes use a wide array of complex compounds to produce intensely vivid colors. Could any of these artificial pigments combine blue and red wavelengths?

Most synthetic purple dyes create the color through a mix of blue and red components. For example, modern printer and artist pigments blend organic or inorganic compounds to absorb wavelengths between blue and red.

However, at least one artificial pigment does appear to reflect close to true blue and red wavelengths simultaneously.

Nickel dithiolene compounds can be synthesized into thin crystalline sheets with a blue-red metallic shine. The crystals absorb green/yellow light, while reflecting both blue and red peaks when measured with spectrophotometry. This likely arises from the nickel ions interacting with sulphur atoms in the dithiolene ligands.

So while examples are still extremely rare, human chemical engineering does seem capable of purposefully creating pigments with true blue-red optical properties.

The Limits of Blue-Red Perception

Even if a true blue-red pigment can be synthesized artificially, would we actually perceive it as a new color? Or would our brains simply process it as a shade of purple?

The way our eyes and brains process color is complex. We have three types of cone cells for absorbing red, green and blue wavelengths. There are no cone cells specifically tuned for combinations like blue-red. Intermediate colors are constructed in our brains from the cone inputs.

In the case of purple hues, our brains likely convert the mix of blue and red wavelengths into a perceptual gradient between the two. We automatically parse purple as a color distinct from, but related to, blue and red.

So a blue-red pigment might physically reflect two wavelengths, but our perception collapses it into a single shade of purple. We lack the biological hardware to experience true blue-red as its own color.

There are colors we cannot even imagine because our eyes cannot see the wavelengths. Magenta, for example, does not exist on the spectrum – it is a color constructed by our brains. In the same way, blue-red appears impossible for us to perceive as a separate color.

Color Spaces Beyond RGB

The RGB color model relies on mixing red, green and blue light. But other color systems exist that could, in theory, accommodate a blue-red color.

The CMYK (cyan, magenta, yellow, black) model works in pigments. Since it mixes pigments subtractively, combining cyan and magenta theoretically could result in a blue-red. However, in practice the result would remain a purple color for the same perceptual reasons above.

More advanced color models such as CIE L*a*b* or L*u*v* were designed to map human perceptual color space. The L* axis represents lightness, while a* and b* or u* and v* are color opponent dimensions based on green-red and blue-yellow. In CIE L*a*b* space, blue-red would equate to high positive a* (redness) and high negative b* (blueness) values. But again, we would simply perceive this as a purplish color rather than a distinct blue-red.

While mathematical color models provide intriguing possibilities, they do not overcome the limitations of human visual perception. Any blue-red color would invariably translate to variations of purple in our mind’s eye.

Synesthetic Blue-Red

Humans with the condition synesthesia can sometimes perceive colors differently from the rest of us. In particular, chromesthesia causes people to associate sounds with visual colors.

Could a person with synesthesia potentially perceive a “blue-red” color that we ordinarily could not? Perhaps a single wavelength of light could trigger their chromesthesia to generate simultaneous blue and red color sensations.

Documented experiences of chromesthetic synesthetes provide tantalizing clues. Some report seeing a color called “brown-note blue” in response to bass frequencies. Others describe a distinct “red-blue” triggered by certain chords played on piano.

So it appears at least some synesthetes can perceive colors that combine wavelengths from opposite ends of the spectrum. However, the effect seems maddeningly inconsistent and impossible to verify or replicate in other observers.

While synesthesia opens biological possibilities for perceiving something akin to blue-red, it likely remains confined to a sparse number of brains wired differently than the rest of humanity. For the vast majority of people, blue-red elicits purple and only purple.


In investigating the notion of a “blue red” color, we have explored light, pigments, perception and special cases like synesthesia.

The conclusion is that while possible in narrow laboratory conditions, a true blue-red color remains largely elusive. Physics allows blue and red wavelengths to be combined additively or reflected simultaneously. But human perception invariably filters this into shades of purple.

So next time you’re discussing colors, don’t be fooled into believing blue and red can create a single new color. Blue mixed with red produces purple – that’s just the way our visual system sees it.