Why does mixing blue and yellow create green?

  • Context: Undergrad 
  • Thread starter Thread starter Zalajbeg
  • Start date Start date
  • Tags Tags
    Mixing Work
Click For Summary

Discussion Overview

The discussion revolves around the mechanisms of color mixing in paints, specifically addressing why mixing blue and yellow results in green. Participants explore the implications of different models of color mixing, particularly the subtractive color model, and question the nature of pigment interactions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant proposes two options for how paint mixing works: Option 1 suggests a mixture absorbs all wavelengths of both paints, while Option 2 suggests a mixture retains original pigments reflecting different wavelengths.
  • Another participant questions how mixing magenta and yellow can produce orange if magenta absorbs green light, leading to confusion about the reflected colors.
  • A participant expresses uncertainty about how mixing yellow and blue results in green, suggesting that if yellow absorbs blue and blue absorbs red and green, the outcome should be black or gray.
  • One participant introduces the idea that subtractive absorption can be likened to placing bandpass filters in series, noting the complexity of pigment interactions and the need for response curves to understand the results.

Areas of Agreement / Disagreement

Participants express differing views on the mechanisms of paint mixing, with no consensus reached on whether the absorption model or the pigment reflection model is correct. The discussion remains unresolved regarding the specific outcomes of mixing different colors.

Contextual Notes

Participants highlight limitations in understanding due to the complexity of pigment interactions and the lack of detailed response curves for the pigments involved.

Zalajbeg
Messages
77
Reaction score
3
I am curious about how mixing paints works. If I mix an ideal paint A and an ideal paint B what is the product mixture C? Is it (Option 1) a mixture absorbs all the range A absorbs and absorbs all the range B absorbs OR is it (Option 2) a mixture with original A and B pigments therefore some pigments reflecting what A reflects and some pigments reflecting what B reflects.

If the Option 1 is true then it would not be possible to get a colour like orange with cyan-magenta-yellow model as mixing magenta and yellow would create something absorbs both green and blue. The product would be red.

If the Option 2 is true then I wonder how is it possible to get a red colour. As in this option mixing magenta and yellow would create a mixture with pigments reflecting blue & red and pigments reflecting green & red. The product must be something like (R:255, G:128, B:128), as all the pigments are reflecting red, half of them reflecting blue and half of them reflecting green.

Also from my childhood I remember mixing yellow and blue and getting a greenish colour. When I study the subtractive model it does not make sense.

If we consider the Option 1 is true then it means mixing yellow (absorbs blue) and blue (absorbs red and green) should make it black. If Option 2 is true I should have something reflecting all the primary colours and get a white or gray. Why mixing blue and yellow makes green? Is it because the pigments are not ideal?
 
  • Like
Likes   Reactions: Stephen Tashi
Physics news on Phys.org
kuruman said:

Thanks for the link. I agree that full level of yellow and a partial level of magenta creates orange. However my problem is rather on the mechanisms of the paint mixing.

My questions are basically:

* How do I get orange by mixing yellow and magenta, in other words if magenta absorbs the green light how does the mixture reflects some?
* How do I get red by mixing yellow and magenta, what makes the mixture absorbing all the green light?
 
I think subtractive absorption seems to be simply placing bandpass filters in series. These filters are very broad and imperfect. It is difficult to talk through results unless we have the response curves for the filters and the wavelengths being applied. The colour printing experts seem to have been able to work it all out.
 

Similar threads

  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 98 ·
4
Replies
98
Views
10K
  • · Replies 8 ·
Replies
8
Views
10K
  • · Replies 4 ·
Replies
4
Views
1K
  • · Replies 207 ·
7
Replies
207
Views
14K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 21 ·
Replies
21
Views
3K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 40 ·
2
Replies
40
Views
4K