– What happens when an artist mixes paint for a painting? Are the pigments actually changing physically/chemically? What is actually happening to make the paints change color?
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Interesting fact: If you mix primary colors using paint you will get something close to black or dark grey. If you combine primary colored beams of light, they will appear as white.
To piggyback off of this ELI5, can our eyes tell the difference between these fine paint/pigment particles that are mixed and a true mixed-color paint/pigment particle?
For example, if we compared a green made by mixing yellow and blue vs. a naturally occurring green pigment like from plants?
I want to add a level of detail.
Those comparing it to mixing pingpong balls are right, but it goes a little deeper.
We see the color from each pigment because of the light that they reflect back to our eyes. We don’t see the colors they absorb
When individual, tiny bits of pigment are packed really close together, the light that some reflect will be absorbed by others.
If you mixed tow pigments that were really and truly only reflecting one wavelength, then they would become black when mixed because each pigment would absorb the wavelength the other one reflects. That’s why subtractive color mixing converges on black. It’s why a color you mix can be darker than either of the parts.
Luckily, well made pigments often have a somewhat wide reflection of wavelengths. What you see when you mix two pigments, are the wavelengths they have in common.
This is why the grade school idea of red yellow and blue being perfect primary mixing colors is flawed, and why you may have been frustrated in the past getting colors more gray or darker than you expected. Cyan, Magenta, and a bright yellow are slightly better as pigment primaries. But to get the widest range of mixed colors, you really need more than three primaries.
I also want to tell you about Streak.
If you take a chunk of a mineral or colourful rock (lets say it’s dark blue) and grind it up into a powder to mix with oil to form a paint, it’s possible that the ground up rock powder won’t also look dark blue. Maybe it now looks light blue.
So your dark blue rock only makes light blue paint.
It’s the size of the little rock particles, bouncing with the light, that ‘change’ the colour to our eyes.
Because of this, not all rocks/minerals are used to make paint. In the pre-industrial era (pre-1800s), there’s only something like 25 minerals commonly used to make paint in the Western part of the art world. There are also a few other things used to colour paint, like bugs or plant dye, but most paintings are made with crushed mineral/rock paint.
Source: I was a forensic art chemist.
You can right now see how we perceive very small objects, take a magnifying lens and see your phone’s screen, you can see how tiny LEDs of 3 primary colours mix up to produce different colours
Well magic seems to never be the correct answer… just once I want the ELI5 answer to be nothing else besides magic.
It’s analagous to your TV or monitor, which actually has only 3 colours (red, green, blue) but as long as you’re far enough back to not distinguish the pixels your eye blends them into thousands of apparent colours based on the relative strengths of each. The eye itself has only 3 color receptors and is built to perceive all the rest through signal processing. The brain does some, too.
look at color print on newspaper or magazine, get a magnifying glass ans look real close. You will see most likely colored dots a process using CMYK(Cyan Magenta Yellow and blacK) inks. This 4 color process can basically make any non white color, and if you print on white paper then everything is good. Technology has advanced enough where we know how far apart to put those 4 dots from each other to achieve every color. You may ask why Cyan and magenta and not the primary colors like blue and red,? This basically comes down to the amount of color used to achieve a different color.
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