"Q-switching" is a trick of laser engineering. A shutter inside the laser holds energy back while it builds up, then releases it all at once. The result is a pulse that lasts only nanoseconds but carries enormous peak power.
That speed is the point. Tattoo ink and melanin absorb the light and heat instantly. Because the pulse ends before the heat can spread to neighboring tissue, the particle fractures rather than the skin burning. Dermatologists call this selective photothermolysis: destroy the target, spare the surroundings. Your immune system then clears the fragments over weeks, which is why tattoo removal takes months rather than one visit.
A picosecond laser takes the same idea further. Its pulses are roughly a thousand times shorter, so more of the energy goes into mechanical shattering and less into heat, producing finer fragments and fewer sessions. The Q-switched laser is the older, slower version of the same physics — not a different or discredited technology, just less efficient.
Q-switched machines come in several wavelengths, and the wavelength determines what the beam can target.
Ask which wavelength will be used and why. For black ink or for deeper skin tones, the answer should involve 1064 nm.
Ask for a test spot if you have brown or Black skin, and have it read two to four weeks later.
Photograph your tattoo or spots yourself in consistent light. Progress across a long course is hard to judge from memory.
Ask what the realistic total number of sessions is for your tattoo, and what the total will cost. Q-switched courses are longer than pico courses.
No sun, sunbeds or self-tanner on the area.
Pause retinoids and exfoliating acids on the area for several days.
Antiviral tablets from the day before if you get cold sores and the area is near the mouth.
Clean, bare skin over the treatment area.
Numbing cream 30 to 60 minutes ahead for tattoo work. A few spots usually needs none.
Everyone in the room wears protective eyewear.
The provider fires a few test pulses at an edge and watches the skin before treating the rest.
Each pulse feels like a hot rubber band snap or a splash of grease. Tattoos are more painful than spots, and bony areas more painful than fleshy ones.
Treated pigment usually frosts white within a second. That is gas escaping from shattered particles and it fades in 15 to 20 minutes.
A few spots takes a couple of minutes. A hand-sized tattoo takes 10 to 20. Big pieces get split across appointments.
Cold air or ice is used during and afterwards. Tattoo areas get ointment and a dressing before you leave.
You go home red, swollen and warm, and tattoo areas often look welted.
Practical rules: gentle washing, keep it moisturized, no pools, hot tubs or heavy sweating until scabs are gone, and daily sunscreen on treated skin for at least a month.
There is no home Q-switched laser. The peak powers involved are far beyond anything sold to consumers.
Handheld "picosecond pens" and blue-light tattoo removal devices sold online are not Q-switched lasers, do not remove tattoos, and can burn skin and damage eyes. Tattoo removal creams cannot reach ink held in the dermis; anything strong enough to reach it would scar you.
For flat brown spots, an at-home routine — daily sunscreen, a retinoid, and a lightening agent such as azelaic acid, tranexamic acid or alpha arbutin — is slower but genuinely useful and prevents new spots.