The Pigmentation Guide

How laser clears sun damage. The mechanism, step by step.

Laser doesn't wipe pigment away. It delivers energy to melanin in pulses faster than a billionth of a second, fractures the pigment into microscopic fragments, and lets the body clear them through the lymphatic system over the following weeks. The four-step mechanism, in the order your skin experiences it, plus why a course of sessions does what one cannot.

By Pink Laser Clinics Published 23 April 2026 Last reviewed 23 April 2026

Editorial portrait of a young woman with freckled skin, dark bobbed hair, and gold drop earrings, against a sage green background.

Most explanations of how laser treats sun damage are either too vague ("it targets the pigment") or too technical to be useful. This piece lives in the middle. A clear walkthrough of what actually happens when a Q-Switched Laser is used to clear solar lentigines from the skin, step by step, in the order your body experiences them.

There are four steps. The light meets the pigment. The light gets absorbed. The pigment fragments. The body clears the fragments. Pink's dermal therapists run this sequence using the Fotona StarWalker MaQX, a Q-Switched platform purpose-built for pigmentation work.

First, what sun damage actually is

Sun damage on the skin (clinically, solar lentigines) is pigment. Specifically, it's excess melanin produced by melanocytes in the epidermis in response to cumulative UV exposure. Each episode of sun exposure in your twenties, thirties, and onward triggers melanocytes to produce more pigment as a defensive response. Over time, melanocyte numbers in heavily exposed areas increase, and the pigment they produce clusters into the flat brown patches most patients recognise as age spots.

This matters for the mechanism. The laser isn't working on dead skin, dry skin, or surface texture. It's working on melanin, a specific pigmented molecule with specific optical properties. Every step of the process that follows depends on those properties.

Step 1: The light meets the pigment

Every laser emits light at a specific wavelength. The wavelength matters because it determines which molecules in the skin will absorb the light and which won't. Melanin absorbs light across a wide range of the visible and near-infrared spectrum. Water-based tissue around it doesn't absorb the same wavelengths the same way.

When the laser fires, the light travels through the skin until it encounters melanin in a sun-damaged spot. That's the moment the work starts.

Step 2: Selective absorption

This is the step that makes laser work at all. The principle is called selective photothermolysis: a specific wavelength of light, delivered fast enough and at the right energy, is absorbed by its target pigment (the chromophore) while mostly passing through the skin around it.

When a Q-Switched pulse enters the skin, it travels through the epidermis until it encounters melanin. The melanin absorbs the light energy preferentially. Surrounding water-based tissue, which doesn't absorb that specific wavelength strongly, transmits most of the light through without converting it to heat. The energy concentrates where you want it (inside the pigment particle) and leaves the rest of the skin largely untouched.

This is why the treatment is so targeted. The laser isn't burning the pigment out in a destructive sense. It's delivering energy to a molecule chosen for its optical behaviour, while the rest of the skin acts like a window the light passes through.

Pink Laser Clinics dermal therapist delivering a Q-Switched Laser session on a patient's face to treat sun damage pigmentation.

Step 3: Photomechanical shattering

Q-Switched Lasers have one defining feature. The pulse width. Each pulse lasts roughly one billionth of a second, a nanosecond. That speed matters more than total energy delivered.

When energy hits a pigment particle over the course of a nanosecond, the particle absorbs the entire pulse faster than the heat can conduct outward into surrounding skin. The particle expands rapidly and fractures mechanically. This is a pressure effect, not a thermal one. The pigment isn't melted or cooked. It's broken into microscopic fragments through a very brief, very contained pressure wave.

The reason speed matters is simple. Heat needs time to travel. At nanosecond speeds, the pigment shatters in isolation, and the tissue around it stays thermally unaffected. That's what makes a Q-Switched Laser the appropriate tool for pigmentation work.

Step 4: Immune clearance

The visible result of a session isn't instant. Immediately after treatment, the pigment in each spot typically looks darker rather than lighter, sometimes grey or slightly ashy. This is called frosting. It's a sign the laser has done its job: the pigment particle has been fractured inside the skin.

Over the next one to two weeks, the body's immune system takes over. Macrophages (a type of white blood cell) engulf the shattered pigment fragments and carry them out of the skin through the lymphatic system. The treated spots gradually lighten as pigment is cleared. Some spots surface as micro-crusts that flake off within a week. Others fade without any visible surface change.

The clearance is biological, not cosmetic. The body is physically removing pigment from the skin.

Why a course, not a single session

Sun damage doesn't clear in one pass. The pigment in each treated patch sits at varying depths, and melanocytes in sun-damaged skin are not just overproducing — they're activated. Even after pigment is cleared, the underlying cells can produce new pigment in response to UV exposure or heat.

A course distributes the work across several sessions, spaced across weeks. Each session catches pigment that was either at a different depth than the previous round or has surfaced since. The body needs the time between sessions to finish clearing fragmented pigment from the previous round before the next round of energy is delivered.

The right number of sessions for your skin gets set at the consultation, based on what the VISIA scan shows about pigment depth and density across the area being treated. The course is then reviewed and adjusted as it progresses.

What your skin looks like after the course

After a completed Q-Switched Laser course for sun damage, treated spots are substantially cleared or gone. What remains is the skin underneath, which often looks more even and more luminous than patients expect, because the original pigment was masking skin tone across a larger area than the spot itself.

Results hold for months to years depending on UV exposure habits. New pigment can form in unprotected skin, which is why post-treatment SPF matters. Pink's dermal therapists plan a maintenance cadence at the end of the course based on your skin's response and your exposure pattern, paired with a supporting topical routine so results hold. The maintenance side of the work is covered in detail in How to Keep Freckles From Coming Back After Laser, the companion piece in this File. The same principles hold for sun damage.

At the clinic

Pink treats sun damage with the Fotona StarWalker MaQX. Each course starts with a VISIA scan that maps pigment at the surface and in deeper layers. The pigmentation work itself is on Pink's pigmentation treatment page.