How Laser Tattoo Removal Works - Smarter Every Day 123

Summary

In this episode of Smarter Every Day, Destin explores the science behind tattoo removal, which involves complex physics, thermodynamics, optics, chemistry, and biology. He discusses how tattoo inks, made of heavy metal compounds, interact with the body’s immune system, and how lasers break down ink particles. Dr. Lappert, a plastic surgeon, explains how the body's white blood cells can remove the shattered ink particles through the liver. The video emphasizes that tattoo removal is far more complex than getting one, and ends with a lighthearted book recommendation for 'The Martian' by Andy Weir.

Takeaways

• 🖊️ Tattoo inks are made from compounds, often containing heavy metals.
• ⚙️ Tattoo removal involves multiple scientific disciplines including thermodynamics, optics, biology, and chemistry.
• 🔬 Tattoos are permanent because white blood cells can't fully engulf large ink particles, though they can remove smaller ones.
• 📉 Over time, tattoos fade as some of the ink is broken down and removed by the immune system.
• 💡 Lasers used for tattoo removal operate on a picosecond scale, delivering extremely short pulses of light to break up ink particles.
• 🌡️ The laser heats ink particles quickly, creating internal stresses due to thermal expansion, which causes the particles to shatter.
• 🩸 After the ink particles are broken down by the laser, white blood cells transport the smaller particles to the liver for excretion.
• 👨‍⚕️ Dr. Lappert, a plastic surgeon, explains that removing a tattoo with a laser depends on the ink color and can take multiple treatments.
• ⚡ The 'frosting' effect seen during laser treatment is a temporary reaction caused by a shockwave at the particle level.
• 🧠 Getting a tattoo is easier than removing one, so it's essential to consider both the design and the chemical makeup of the ink before getting one.

Q & A

What is the main topic of the video?

The main topic is about the tattoo removal process, focusing on the science behind it, including physics, thermodynamics, optics, biology, and chemistry.

What surprising fact does Destin reveal about tattoo inks?

Destin reveals that the bright colors in tattoo inks are created from compounds that often contain heavy metals, which are injected into the body during tattooing.

Why are tattoos difficult to remove?

Tattoos are difficult to remove because the white blood cells in the body are too small to engulf and remove the larger pigment granules in the ink. Over time, smaller particles are removed, but larger ones remain, making tattoos permanent.

How does a laser aid in tattoo removal?

The laser breaks up the larger pigment granules into smaller particles, making them easier for the white blood cells to remove. This process accelerates the body's natural ability to clear the ink through the lymphatic system and eventually through the liver.

What type of laser is used in tattoo removal, and why is it effective?

An ultra-short pulse laser, specifically a picosecond alexandrite laser, is used. It operates at a frequency of about 755 nanometers, delivering rapid pulses that create internal stress in the ink particles, shattering them efficiently.

How does the laser shatter the ink particles?

The laser heats one side of the ink particle so quickly that it causes thermal expansion on that side. The other side doesn't have time to heat up, creating internal stress that rips the particle apart.

What happens to the broken ink particles after laser treatment?

After the laser breaks the ink particles into smaller pieces, white blood cells absorb them and transport them through the lymphatic system to the liver, where they are processed and eventually excreted from the body.

What is the 'frosting' effect seen during laser tattoo removal?

The 'frosting' effect is a temporary white appearance on the skin immediately after the laser pulse. It is caused by a shock wave at the particle level, which briefly elevates the top layer of skin.

Why do tattoos fade over time even without removal?

Tattoos fade over time because smaller ink particles are gradually absorbed and removed by the body's immune system, leaving only the larger, more difficult-to-remove particles behind.

What advice does Destin give to people considering getting a tattoo?

Destin advises people to carefully consider what they're getting tattooed, both in terms of the design and the chemical composition of the ink, because removing a tattoo is much harder than getting one.