The art of tattooing is not only an expression of creativity but also a fascinating application of science. When a tattoo needle delivers ink into the skin, a myriad of biological processes takes place.
In this article, I’ll walk you through the science behind how tattoo ink is absorbed by the skin, why tattoos are permanent, and the factors that can affect a tattoo's appearance over time.
- Tattoo ink is deposited into the dermis, the second layer of skin, where it's absorbed by skin cells and immune cells.
- Tattoos are permanent because the ink particles are too large to be removed by the body's natural cleaning processes.
- Various factors such as skin type, ink quality, and exposure to sunlight can affect how a tattoo looks over time.
What Happens When Tattoo Ink is Injected into the Skin?
When the needle of a tattoo machine punctures the skin, it carries ink into the dermis.
But why the dermis?
The epidermis, the outer layer of the skin, continuously sheds cells, whereas the dermis is more stable. The dermis provides a relatively stable environment for the tattoo ink, as opposed to the rapidly turning over cells in the epidermis.
In the dermis, immune system cells called macrophages attempt to ‘clean up’ the foreign ink particles. Some of the ink is transported away by these cells, but much of it remains in the dermis, absorbed by fibroblasts (a type of skin cell) and trapped within the collagen matrix.
Why are Tattoos Permanent?
While our bodies are quite efficient at cleaning up foreign materials, tattoo ink particles are usually too large for the macrophages to fully consume and transport away. As such, the ink particles remain trapped in the dermis, visible through the outer layer of skin.
How Does the Body React to Tattoo Ink?
When the skin is punctured, the body responds as if it’s been injured - because it has. The immune system springs into action to prevent infection and start repairing the damage. It’s this immune response that is integral to both the permanence of tattoos and the body's ability to remove ink through laser tattoo removal.
What Factors Affect Tattoo Ink Absorption and Appearance?
Skin Type: Different skin types react to tattoo ink in various ways. For example, oily skin might cause ink to spread slightly, affecting the tattoo’s sharpness.
Ink Quality: High-quality inks tend to maintain their vibrancy longer. Some cheap inks can fade quickly or cause allergic reactions.
Sun Exposure: Ultraviolet (UV) rays from the sun can cause tattoo ink to break down over time, leading to fading.
Age: As skin ages, it loses collagen and elastin. This can cause tattoos to sag or blur as the skin becomes less firm and elastic.
Tattoo Depth: If the ink is deposited too shallowly, it ends up in the epidermis and will be shed. If it’s too deep, the tattoo might not be as sharp.
How Do Laser Tattoo Removals Work?
Laser tattoo removal uses highly concentrated light beams to break up the ink particles in the dermis. Once the ink particles are broken into smaller fragments, the macrophages are more successful in consuming and carrying them away.
Safety Considerations and Tattoo Ink
It's essential to be aware of the contents of tattoo inks. Some inks contain metals or other substances that can cause allergic reactions. “Since tattoos are not regulated in any way, there are many unknowns that could pose potential problems for consumers in terms of the inks and tools used,” Dr. Michi Shinohara, a clinical assistant professor of dermatology at the University of Washington in Seattle, said in an American Academy of Dermatology news release.
It is important to talk to your tattoo artist about the inks they use.
The Future of Tattoo Science
As the tattoo industry evolves, so does the science behind it. Emerging technologies may soon bring new types of tattoo inks and delivery methods. For instance, researchers are looking into “bio-inks” and temporary tattoo inks that last longer than traditional temporary tattoos but are not permanent.
The permanence of tattoos is a fascinating interplay between art and science. The role of the immune system, the structure of the skin, and the properties of tattoo ink all contribute to the absorption of tattoo ink in the skin and the longevity of tattoos. Understanding the science behind tattooing can lead to more informed choices and a deeper appreciation of this ancient art form.
For more information on our sets, please take a look at our piece on Xtreme Inks: Artist Collections.