When we think about mixing colors, we often assume that combining two primary colors like blue and yellow will make a secondary color like green. However, this isn’t always the case. While mixing blue and yellow paints or dyes will create green, mixing blue and yellow light actually produces a different result. So what color does make blue turn green when mixed? The answer has to do with the physics of light and vision.
How Light and Pigments Create Color
To understand what color mixes with blue to make green, we first need to understand the difference between how color works with light versus pigments like paint and ink.
Light is made up of different wavelengths, each corresponding to a color. Red light has a longer wavelength while blue light has a shorter wavelength. When different colored lights mix, they produce additive mixing, meaning their wavelengths combine to form new colors. For example, combining red and green light makes yellow light.
On the other hand, pigments like paint and dyes absorb certain wavelengths of light and reflect others. This creates subtractive mixing – the more pigments you combine, the more wavelengths get absorbed. Yellow paint absorbs blue light while reflecting red and green. Blue paint absorbs red and green while reflecting blue. When you mix blue and yellow paints, both the blue and red/green wavelengths get absorbed, leaving only green being reflected. This is why mixing blue and yellow paint makes green.
So while blue and yellow pigments take away wavelengths to make green, blue and yellow light combine their wavelengths to make a different color.
The Additive Mixing of Blue and Yellow Light
When blue light (shorter wavelengths) and yellow light (longer wavelengths of red and green) mix together, their wavelengths blend to produce white light. This is because white light contains a full spectrum of wavelengths.
So rather than making green, combining pure blue light and pure yellow light makes white. You can see this for yourself by shining a blue laser pointer and a yellow laser pointer on the same spot – the overlapping area will appear white.
| Color | Wavelengths |
|---|---|
| Blue light | Short wavelengths |
| Yellow light | Longer red + green wavelengths |
| Blue + Yellow light | Full spectrum → White light |
This table shows how the combination of short blue wavelengths and longer yellow (red + green) wavelengths creates the full spectrum of white light.
The additive mixing of light is different than the subtractive mixing of pigments. So if you shine blue and yellow lights together, you’ll see white, not green.
Cyan Light Mixes with Blue to Make Green
If blue and yellow light make white, what color does mix with blue to make green light? The answer is cyan.
Cyan light is made up of green and blue wavelengths. When you add cyan and pure blue light, the overlapping blue wavelengths become enhanced while the unique green wavelengths from cyan remain, producing green light.
In other words, cyan contains green and blue light, so when you mix it with pure blue, the blue reinforces itself while the green stands out – creating green.
| Color | Wavelengths |
|---|---|
| Blue light | Short blue wavelengths |
| Cyan light | Short blue + medium green wavelengths |
| Cyan + Blue light | Enhanced blue + medium green → Green light |
This table demonstrates how cyan’s green wavelengths mix with blue’s enhanced blue wavelengths to create green light.
So while blue and yellow pigments combine to make green through subtractive mixing, blue and cyan light blend through additive mixing to produce green.
Other Ways to Make Green Light
In additive light mixing, any combination of red, green, and blue light can make other colors. Here are some other ways to mix colors of light to produce green:
– Red + Blue light – Red’s long wavelengths combined with blue’s short wavelengths makes green’s medium wavelengths.
– Red + Cyan light – Cyan contains green so its green wavelengths mix with red to make enriched green.
– Green + Magenta light – Magenta has red and blue which combine to reinforce green.
– Yellow + Cyan light – Yellow’s green wavelengths mix with cyan’s green to make stronger green.
So while cyan + blue makes the purest green light, you can mix other color pairings to also produce green through additive mixing. The key is combining wavelengths that cover the medium green range when added together.
Why Understanding Additive vs Subtractive Mixing Matters
The physics of how color works with light versus pigments explains why mixing blue and yellow gives different results. When working with light sources like LED signs, TV/phone screens, or stage lighting, additive mixing of light colors applies. But when working with paint, dye, or pigments, subtractive mixing of those medium is needed.
Misunderstanding these two different mixing models can lead to mistakes like:
– Buying blue and yellow paint expecting green paint
– Combining blue and yellow stage gels but getting white light, not green
– Making a blue and yellow website graphic but having it display as white
So being aware of the underlying principles explains how cyan makes blue turn green with light, while yellow makes blue turn green with pigments. Understanding the science allows you to predict and control the colors you want when working with different mediums.
Conclusion
When most people think about mixing colors, they default to the idea of paints and subtractive mixing. However, with light it’s important to remember the physics of additive color mixing. Blue and yellow light combine to make white, while blue and cyan light overlap to produce green by reinforcing the medium green wavelengths.
So the key takeaways are:
– Blue + yellow pigments = green through subtractive mixing
– Blue + yellow light = white through additive mixing
– Blue + cyan light = green through additive mixing
Knowing the theory empowers you to plan color mixing to obtain the desired results, whether working with light sources or pigmented materials. Understanding the science of how colors interacts allows you to intentionally craft the perfect hue.
