Why does eyebrow PMU turn blue? The Tyndall effect explained
Why eyebrow PMU can look blue even with brown pigment: the Tyndall effect, and how deeper pigment placement raises the risk of a bluish tint.
A real nightmare for PMU (permanent makeup) artists is when you do the work with a brown pigment, and the result has a blue tint...
You are confused, and so is the client. Accusations start flying at you: "What happened to my eyebrows? Why are they bluish? How can I go out like this?"
Let's figure out what can cause this "blueness" after a PMU session.
What is the Tyndall effect, and how is it related to bluish eyebrows?
Look: how we perceive the colour of pigment in the skin depends (among other things) on how deep the ink lies, and it is explained by a physical phenomenon, the Tyndall effect!
According to it, in a non-uniform medium short waves are always reflected first. They are violet, blue and light blue in colour.
Human vision perceives only the waves reflected from a surface!
In our case, the non-uniform medium is the skin. So light passing through it is strongly refracted and reflected by cells, fibres and other structures.
Light reaches the pigment, is reflected from it and once again has to pass through the obstacles in the dermis and epidermis to reach the surface.
And we see the reflected wave together with its colour.
To make this clearer, I have attached some illustrations:
Can this effect be avoided? Or its influence on the result "reduced"?
If the pigment lies shallow in the skin, we see its most natural shade. But when it goes deeper into the dermis, the blue part of the spectrum starts being reflected by the non-uniform medium before it even reaches the ink itself!
As a result, we see a bluish colour of the tattoo or PMU, even if brown or black ink was used.
The conclusion: how the colour of PMU is perceived depends on how deep the pigment lies. The deeper the ink is placed, the higher the risk of seeing a blue tint.
Why deep pigment looks blue
Move the slider: the same brown pigment at different depths.
A simplified illustration of the Tyndall effect: the deeper the pigment, the more short blue wavelengths in the reflected light.
Frequently asked questions
Why do eyebrow tattoos turn blue?
Because of the Tyndall effect: in a non-uniform medium such as skin, short blue waves are reflected first. When the pigment lies deep in the dermis, the blue part of the spectrum is reflected before light reaches the ink, so brows look bluish even with brown or black ink.
How can you reduce the risk of blue eyebrow PMU?
How the colour is perceived depends on pigment depth. Shallow pigment shows its most natural shade, and the deeper the ink is placed, the higher the risk of a blue tint.
