Advantages

Realism

The shader is built on physics equations and considers concepts like Rayleigh scattering, wave interference, internal reflection, and absorption.

So, when you make a shader with Iridescence, it looks realistic in any environment. Workarounds with color ramps might also give rainbow-like patterns, but they will feel out of place. They wouldn't react to lighting as you'd expect. The color wouldn't change as it does in real life. That all gives away that it's a render. If the goal is photorealism, looking like the material isn't enough, it needs to be the material!. People can tell the difference!

Saving time

Even if a workaround could look acceptable in certain situations, it would still cost much more time. You might spend valuable time going back and forth between settings, comparing test renders to references. Because workarounds are not physically correct, you will need to start all over again when the lighting or environment changes.

With Iridescence, you would look up the required values on the internet within a single minute. After entering them and seeing the result looking like expected, you can safely leave the material behind and move on within minutes. No node troubleshooting, endless tweaking, or test renders are needed. It's immensely more time-efficient and comfortable.

Easy of use

Use the node as the colour of a metallic or glossy shader. Then enter the IOR and film thickness values you found. Hook up a normal map and that's it!

For a film on a transmissive base like water, , or air, simply set the Transmission to 1. The colour will be corrected and a physically correct alpha mask is generated, you can use it directly as a factor to mix with any non-opaque shader.

Alternatively, you can simply use one of the included materials. Then adjust the settings from there if necessary.

Control and flexibility

The way the thin-film node integrates into the shader workflow, leaves almost all control to the end-user. It can perform very well at modeling just the base thin-film effect. For other cases:

• A texture can be used as film thickness to create detailed patterns.
• Artificial override settings are available for more artistic control.
• The node's output can be manipulated and used for any shader you want.

Because of this, while being realistic, it allows artistic control and stylized shaders.
The flexibility is demonstrated by the completely different materials in the featured gallery, all of them built on the same thin-film node.

Accuracy

To verify that it's accurate, here it is compared to soap bubble colours measured in the real world. The rectangle below shows Iridescence, with the same thickness gradient as input (0-1 um).

Reference Chart (source):

Blender cycles (nodes):

As expected, the exact same pattern and scale appeared without any adjustments, proving that material properties you can find on the internet can be used as-is.