There are no silly questions (if they are sincere). Someone once asked me: “What color do you add to orange to make blue?” Any artist, familiar with color-mixing, would most likely respond that this can’t be done, no matter what you add. But their answer would be wrong! There is a way. You add white to orange to get blue. Sounds completely crazy -- but only if you’ve never truly studied color!
You will need one more ingredient to add: time, 30 seconds.
Of course, this will not help someone with a bucket of orange paint who would rather have blue. However, since this question had no specifics, I can answer in a way that brings in Color Theory and the method called Optical Color Mixing.
Mechanical mixing of pigments is not the only way to obtain new colors. New colors can also be created optically, by means of simultaneous contrast. This visual alchemy is based on the fact that any color produces its complementary (opposite) color on our retina as the after-image.
Here is how you can make blue from orange:
Take a neon-orange paper or fabric. Take white paper and cut it into tiny pieces, place them on the orange surface and look, and in 30 seconds they will turn blue. So, technically, by adding white to orange, we made blue.
The rest of the answer is for those who want to explore this optical phenomenon further and enhance this color transformation, to experience the side of color that is as mysterious as magic itself. If we stare at our setup for ten more seconds, that blue will start intensifying, turning dark-blue - darker than the orange background! This will defy common sense: white is supposed to be the lightest color!
You can make it even more surprising by replacing white paper with gray, also cut into pieces, and over the orange they’d turn bright-blue.
Actually, you can do it without cutting paper: just stare at that orange for a few seconds, then shift your gaze to any white surface - and you’d see blue as the afterimage. The impermanence of that blue may feel like it is different in nature from “normal colors” - and you may think: “This is just an impression, an optical imprint, an illusion”. However, the nature of that optical blue is in line with the nature of the regular colors around us - they too are the product of light and are created in the brain.
You don’t even need the white surface: stare at that orange for 30 sec., then close your eyes, and you’ll see the same blue under your eyelids.
But the most striking (maybe slightly uncomfortable) metamorphosis will happen if you place your hand on that neon orange, because in 30 seconds your skin will start turning blue (you may need more than 30 seconds for the total effect because it will take time to start believing your eyes). You might experience a slight concern - your hand will look like it has been severely bruised, and that color will look absolutely real.
In addition to being a fun party trick, this juxtaposing of colors side-by-side to create new colors is actually used in various industries: home decor, fashion design, theater, cinema, art, and photography. There are art movements (Impressionism, Pointillism) that utilize both ways of color-mixing: the actual mixing of pigments on the palette and creating additional visual effects that happen in the eye.
As an art teacher, I demonstrate Simultaneous Contrast to artists by placing my hand over different colors, to show how the color of the skin gets changed. It is mind-blowing for everyone who is observing it happening, including me! While introducing this color transformation, each time I am surprised by it myself. It is impossible to get used to!
There is more to color than the eye sees. And here is the most uncomfortable truth: the more you study color and learn about it, the less you understand it. And vice versa, the less you know about color, the more simple the color feels.
This may not be the answer the person was looking for, but I am using this as an opportunity to throw a wrench at the belief of "familiarity with color". I also feel I may need to support this lengthy text with a short video, showing it all happening in real time.
I love “ridiculous” questions! They force us to look under the surface, because almost nothing is as simple as it at first appears to be.