<p>Not all liquid or things that are yellow become red when they exist in large quantity. For example, beer, vegetable oil, and normal urine never look red even in large quantity, like in a vat. It really depends on the optical properties of the liquid and the suspended particles in it.</p>

<p>The optical properties of something depend on both its intrinsic factors such as its reflectance, transmittance, and absorptance of the light and the extrinsic factors such as its thickness, the surface that it’s on, the angle of light incidence, and the polarization of the incident light. (This is not to mention psychological factors like the mood when you look at that thing or the surroundings colors or compositions of that thing, which can make that thing look different.)</p>

<p>That’s why a thin film of water is colorless but a large body of water like the lake looks blue. And that’s why there is a phenomenon called iridescence – the phenomenon that certain surfaces appear to change color as the angle of view or the angle of illumination changes – like changing rainbow colors on a soap bubble or on a colorless CD surface.</p>

<p>In your case, I think the color reflection and transmission properties of the ink are different. The ink probably reflects mainly the yellow color, so it looks yellow when reflection of colors is the major event – as when the ink is painted on a surface. But the ink probably transmits more of the red color than the yellow color, so it looks red when transmission of colors is the major event – as when you look through it.</p>

<p><strong>N.B.</strong> I think you’ll probably get better answers than mine by posting the question on the Physics forum.</p>

<p><strong>References.</strong></p>

<ol>
<li><p><a href="https://light-measurement.com/reflection-absorption/" rel="nofollow noreferrer">II.8. Reflection, Transmission, and Absorption</a> Gigahertz-Optik.</p></li>
<li><p><a href="https://sensing.konicaminolta.us/blog/elements-that-affect-the-appearance-of-color/" rel="nofollow noreferrer">Elements that Affect the Appearance of Color</a> Konica Minolta.</p></li>
<li><p><a href="https://en.wikipedia.org/wiki/Iridescence" rel="nofollow noreferrer">Iridescence</a> Wikipedia.</p></li>
</ol>

CC BY-SA 4.0
2020-02-23T12:49:41.933Z
I thought it was a perceptual illusion but your explanation makes much more sense. I've found [this](https://hueangles.blogspot.com/2009/02/michael-h.html) also, in support of the optical explanation. And then how could I forget about beer? :-)
Arch Stanton
CC BY-SA 4.0
2020-02-23T08:23:42.100Z
2020-02-23T08:23:42.100Z
user287279
<p>A transparent blue inkjet cartridge looks deep blue, a red one looks deep red, but a yellow one looks red. Tea also looks yellowish when it's shallow and reddish otherwise. Red is another colour, a different wavelength, so why does deep yellow look red?</p>

<p><a href="https://i.sstatic.net/A4zUC.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/A4zUC.jpg" alt="enter image description here"></a></p>

CC BY-SA 4.0
2020-02-22T13:41:46.060Z
Welcome to Psychology.SE. What have you read regarding Red, Green and Blue colour waveforms etc.?
Chris Rogers
CC BY-SA 4.0
2020-02-23T12:48:34.523Z
Hello @ChrisRogers , thank you. I'm studying chemistry at university; they teach us about light in spectroscopy and physics courses. Anyway, I was mistaken in thinking it is a perceptual illusion. It's the actual color that comes out of the bulk ink that's filtered towards red.
Arch Stanton
CC BY-SA 4.0
2020-02-23T19:07:12.513Z
I don't see how this is related to psychology or neuroscience.
Steven Jeuris
CC BY-SA 4.0
2020-02-24T10:36:34.383Z
Greetings! This showed up on Physics Meta rather than on Physics. I've flagged for the mods here to try migrating it again.
rob
<color>
Why does "bulk" yellow ink look red?
Arch Stanton
# Why does "bulk" yellow ink look red?

(Asked by: username_0 on 2020-02-22)

A transparent blue inkjet cartridge looks deep blue, a red one looks deep red, but a yellow one looks red. Tea also looks yellowish when it's shallow and reddish otherwise. Red is another colour, a different wavelength, so why does deep yellow look red?

[![enter image description here](https://i.sstatic.net/A4zUC.jpg)](https://i.sstatic.net/A4zUC.jpg)

**Tags:** color

> **Comments:**
> **username_1**: Welcome to Psychology.SE. What have you read regarding Red, Green and Blue colour waveforms etc.?  
> **username_0**: Hello @ChrisRogers , thank you. I'm studying chemistry at university; they teach us about light in spectroscopy and physics courses. Anyway, I was mistaken in thinking it is a perceptual illusion. It's the actual color that comes out of the bulk ink that's filtered towards red.  
> **username_2**: I don't see how this is related to psychology or neuroscience.  
> **username_3**: Greetings! This showed up on Physics Meta rather than on Physics. I've flagged for the mods here to try migrating it again.  

---

## 1 answers

### Answer by username_4 on 2020-02-23. Score: 1 | Accepted answer

Not all liquid or things that are yellow become red when they exist in large quantity. For example, beer, vegetable oil, and normal urine never look red even in large quantity, like in a vat. It really depends on the optical properties of the liquid and the suspended particles in it.

The optical properties of something depend on both its intrinsic factors such as its reflectance, transmittance, and absorptance of the light and the extrinsic factors such as its thickness, the surface that it’s on, the angle of light incidence, and the polarization of the incident light. (This is not to mention psychological factors like the mood when you look at that thing or the surroundings colors or compositions of that thing, which can make that thing look different.)

That’s why a thin film of water is colorless but a large body of water like the lake looks blue. And that’s why there is a phenomenon called iridescence – the phenomenon that certain surfaces appear to change color as the angle of view or the angle of illumination changes – like changing rainbow colors on a soap bubble or on a colorless CD surface.

In your case, I think the color reflection and transmission properties of the ink are different. The ink pusername_3ably reflects mainly the yellow color, so it looks yellow when reflection of colors is the major event – as when the ink is painted on a surface. But the ink pusername_3ably transmits more of the red color than the yellow color, so it looks red when transmission of colors is the major event – as when you look through it.

**N.B.** I think you’ll pusername_3ably get better answers than mine by posting the question on the Physics forum.

**References.**

1. [II.8. Reflection, Transmission, and Absorption](https://light-measurement.com/reflection-absorption/) Gigahertz-Optik.
2. [Elements that Affect the Appearance of Color](https://sensing.konicaminolta.us/blog/elements-that-affect-the-appearance-of-color/) Konica Minolta.
3. [Iridescence](https://en.wikipedia.org/wiki/Iridescence) Wikipedia.

> **Comments:**
> **username_0**: I thought it was a perceptual illusion but your explanation makes much more sense. I've found [this](https://hueangles.blogspot.com/2009/02/michael-h.html) also, in support of the optical explanation. And then how could I forget about beer? :-)  

---

