How Laser Tattoo Removal Works
Because of the popularity of both tattoos and laser removal, laser technology has come a long way in the last 5-10 years. The technology has been refined to be more effective and cause less damage to the skin. This is good news for people who are looking to get tattoos removed, as they can now do so with less risk of side effects.
The process of laser tattoo removal uses a concentrated burst of light energy to break down the ink particles found in tattoos. The body’s immune system then slowly eliminates these ink particles over time. Every treatment after the first one will break up the ink particles a bit more, until they are eventually eliminated by the body or become transparent. This is why you will see the tattoo fade more over the next 4 to 8 weeks after a removal session, as the body is slowly taking away the smaller fragments.
It sounds simple, but the technology and processes that occur are more complex and deserve a deep dive to fully understand what’s going on.
The three layers of skin
Whether you’re getting a tattoo or getting one removed, the process directly involves the skin. It’s helpful to understand the skin and its layers to fully appreciate the process of tattooing and tattoo removal.
The skin is made up of three layers: the epidermis, dermis, and hypodermis.
|Layer of skin||Position of layer||Function of layer|
Makes new skin
Connects dermis to muscles & bones
Regulates body temperature
How does getting a tattoo work?
Before you remove a tattoo, you need to get one first.
In today’s world, the most common method involves a tattoo machine that inserts ink into the skin via a needle or multiple needles. The skin is punctured repeatedly, ranging from 80-150 times a second.
The ink is initially inserted into the epidermis (top layer of skin) and the dermis (middle layer of skin). As healing takes place, the damaged epidermis regenerates, ridding itself of any pigment. However, the ink stays trapped below between the epidermis and dermis boundary, making the tattoo permanent.
Professional tattoos typically deposit ink into the dermis, whilst more amateur tattoos are usually closer to the surface of the skin.
What lasers are used in tattoo removal?
To have laser tattoo removal, it goes without saying you need a laser - a device that emits a concentrated beam of light.
In tattoo removal, there are two main types of lasers that are used.
- Quality-switched (QS) laser
- Picosecond laser
QS lasers were the first on the scene and in commercial use by the 1990s.
These operate by delivering a huge amount of energy to a concentrated spot, within a short space of time (we’re talking nanoseconds - one thousand-millionth of a second).
The picosecond laser is the latest development, with the PicoSure in 2012 and the more advanced PicoWay arriving in 2015.
The name picosecond refers to the length of time the laser emits its energy. A picosecond is one trillionth of a second. That’s 1,000 times faster than a nanosecond, the pulse duration of QS lasers.
The Importance of Wavelength, Fluence, Repetition Rate, and Spot Size in Laser Tattoo Removal
All light is made up of different wavelengths.
The optimal wavelength used by the laser to remove a tattoo will depend on the colour of the ink in the tattoo as well as the skin colour of the individual receiving treatment.
Fluence is a measurement of energy density. i.e. the amount of energy in an area of a laser.
Higher fluence can result in better tattoo removal, however, it runs the risk of damaging the skin. It’s therefore important to keep fluence at a low enough level to achieve the goal of removing the tattoo, without damaging the skin.
Over the course of treatment, a higher fluence is generally needed as ink density decreases and tattoos become lighter.
3. Repetition rate
A Repetition rate (RR) is the rate at which a laser pulses fire in one second, measured in Hertz (Hz). 1 Hz equals one laser pulse per second.
Different tattoos require different repetition rates.
If the surface being treated is flat and wide, a high RR can be used, shortening the time it takes to treat the skin.
Whereas if it’s an uneven and detailed region, a lower RR is required.
4. Spot size
The spot size is the diameter of the laser beam.
The larger the spot size, the deeper the laser penetrates into the skin. However, it also requires more power (fluence), so the spot size used by a practitioner depends upon many factors, including the size, placement, and colour of the tattoo.
Picosecond laser vs QS laser
A picosecond laser is better at removing tattoos than a QS laser and also reduces the risk of damage to the skin.
The much faster pulse duration has a different effect on the destruction of the pigment. It causes something called a photoacoustic effect, rather than photothermal which is used by the QS laser.
This breaks the ink up into smaller particles to be carried away by the immune system and the reduced heat causes less damage to the surrounding tissue.
The faster speed also means they can operate at a lower fluence (as mentioned earlier) for a successful treatment.
The process of laser tattoo removal
The first step in getting laser treatment for your tattoo is to have a patch test. This will involve treating a small area of your tattoo and looking for clinical end points such as frosting. If the test is successful, you will be able to go ahead with your tattoo removal.
The practitioner will begin by cleaning the area and using a cold air machine to begin numbing the skin. This reduces the amount of pain that could be felt during the process.
The laser is then held against the skin and emits rapid pulses of light. The laser light directly hits the pigments of ink and causes them to shatter, breaking them up into smaller pieces.
As mentioned earlier, if using a QS laser a photothermal effect takes place, which heats up the pigment causing it to break down. When using the picosecond laser it uses a photoacoustic effect, meaning it uses pressure to shatter the pigments.
This means that the picosecond laser is less intense than the QS and as it doesn't use heat, is less painful and less likely to damage the skin.
The role of the immune system in laser tattoo removal
Once the pigment has been broken down, it’s then left to the body and immune system to do the rest of the work.
The human body has specialised cells called macrophages which detect, ingest, and destroy bacteria or other harmful bodies.
These cells will come along to the pigment fragments and begin their work of eliminating them, using a process called phagocytosis.
The lasering process usually needs to be repeated multiple times. This is because each treatment only breaks the ink down so much and it has to be carried away by the immune system before the laser can be used again.
If not enough time is left between sessions, the laser treatment will have very little effect. The standard 8 weeks between treatments was determined by numerous clinical trials performed by Candela Medical, the manufacturer of the PicoWay laser.
The laser used within tattoo removal is really just helping the body do its work.
You will notice that older tattoos have generally faded over time. This is because the body is trying to remove the foreign pigment from the tattoo. As such, older tattoos can require fewer sessions than new tattoos.
The impact of skin colour on tattoo removal
Human skin contains melanin, which impacts its colour. The more melanin, the darker the skin. This also impacts hair and eye colour.
The amount of melanin in different skin impacts the treatment of tattoo removal.
A numerical scale was created called the Fitzpatrick scale. This can be used to help determine the correct course of treatment for that individual.
The higher scale, the less aggressive direct treatment should be, meaning a higher number of sessions is needed. The wavelength of the laser impacts the aggression of treatment. Shorter wavelengths are more aggressive than longer ones.
For example, skin types 1-3 can be very aggressive, skin type 4 should be less aggressive, and skin type 5-6 should be very low.
This is because melanin has a high energy absorption rate. For instance, if you wore a dark shirt on a hot day, you would feel much warmer than if you wore a lighter shirt. That’s because darker pigments absorb a higher amount of energy.
So the more melanin a person has, the more energy is absorbed from the laser. Now you might think that this would mean this would reduce the number of sessions, but it can actually cause skin discolouration.
Therefore a gentler approach is needed to avoid this effect.
|Fitzpatrick type||Skin colour||Characteristics|
|1||White; very fair; red or blonde hair; blue eyes; freckles||Always burns, never tans|
|2||White; fair; red or blonde hair; blue, hazel, or green eyes||Usually burns, tans with difficulty|
|3||White or olive skin tone; fair with any eye or hair colour; very common||Sometimes mild burn, gradually tans|
|4||Brown; common in people of Mediterranean descent||Rarely burns, tans with ease|
|5||Dark Brown; common in people of Middle-Eastern descent||Very rarely burns, tans very easily|
|6||Black||Never burns, tans very easily|
The impact of ink colour on tattoo removal
As discussed earlier, the wavelength from a laser impacts different colours. This is because different colours attract different wavelengths, causing the ink to shatter.
It’s important that where you go for tattoo removal has the right laser that can emit the right wavelength for the colour of your tattoo.
The table below shows which tattoo colours respond to which wavelengths of the PicoWay laser used at Cloak and Dagger.
|Tattoo colour||Optimal wavelength (nm)|
Tattoos are a popular form of self-expression, but what happens when you want them gone? The process of tattoo removal can be lengthy, depending on the colours and type of ink used.
In this article, we’ve discussed the impact that skin colour and ink colour have on the number of sessions needed for tattoo removal.
We hope this has given you a better understanding of the process. If you’re considering laser tattoo removal in london, contact us today to schedule a consultation!