All about Laser Hair Removal (LHR) in a long shot

Laser vs IPL

Different wavelengths of light are preferentially attracted to different structures in the skin. Hairs can be permanently reduced only when the correct wavelengths are used so that the light energy is taken up by melanins and converted to heat energy to destroy hair follicles while minimal energy is transferred to the skin. Thus this heats the hair & reduces the chance of hair regrowth in the future.

IPL are made to produce a band / bandwidth of wavelengths, whereas laser are made to produce one very specific single wavelength of light. Thus, laser is more specific to a given target than IPL, and therefore is more effective than IPL and has fewer side effects and complications.

Not all current IPL & laser devices work effectively to reduce hair permanently.

There are things to consider, principally:

– Wavelenghts (nm)
The laser wavelength for deep, thick & dark hair roots should be 1064nm (Nd:YAG); but it won’t be effective for shallower hair roots.
The laser with wavelength of 755 nm (Alexandrite) & 800-900 nm (Diode) work effectively with shallower, thinner & lighter hair roots.
Many IPLs & Lasers with other wavelengths do not work effectively to retard hair growth. So before you pay, ask the therapist what wavelength they use to remove your hairs? Because if your hairs root deeply, energy form lasers & IPLs with shorter wavelengths won’t reach your hair roots; vice versa shallower hair roots won’t respond well to lasers with longer wavelengths

– Skin colours
Nd:YAG is suitable for all skin types, but Alexandrite & Diode are safe to be used for Fitzpatrick Skin Type 1, 2 & 3 only.
Very dark-skinned individuals need to have a laser with a longer wavelength. The longer wavelength is needed so as not to have the laser energy preferentially absorbed by the top layer of skin as would occur with the shorter wavelength laser. The longer wavelength penetrates deeper and will target the deeper dark pigment decreasing the risk of blisters or burns on the surface.

– Natural Hair Colours
See =>

– Density & diameter your dark hair roots
The treatments are most effective on dense, thick, coarse & dark hair roots because they have a lot of pigment and can absorb a lot of heat. Sparse, fine hairs cannot absorb much heat. Thus, LHR lose efficacy on very thin or vellus hairs.

– Pulse Duration (means how long each laser shot/firing/pulse is allowed to work on you. There are few terms for this meaning such as Pulse Duration or Pulse Width. The longer pulse duration is for the thicker/bigger hair diameter. Longer pulse shouldn’t be used for thinner hairs to prevent damage to adjacent tissue.)

Laser devices operate as continuous wave or pulsed systems (e.g. single or repetitive‑pulsed lasers). Examples of multi-pulsed (in other word, repetitive-pulsed) laser devices are Short Pulsed, Long Pulsed (ms) and Q-switched for different treatment purposes. But long-pulsed lasers in 755, 800-900 & 1064 nm have proved to be effective to reduce hairs permanently.

Q-switched & other short-pulsed lasers which emit much shorter pulses won’t do anything to your hairs except bleaching hair colors. Both the amount, density & size of your hairs will remain exactly the same. Remember! Once hair roots get bleached, IPL & Laser won’t work on lighter hairs 😭.

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– Fluence (J/cm^2), Spot Size (mm) & Repetition Rate (Hz) to be applied are according to different recommendations among different brands.

Fluence means energy of each laser firing/pulse/shot per your body area of 1 square centimetre.

Spot Size or the size of laser aperture

Repetition Rate (Hz) is the number of laser pulse per 1 second.

In general, the smaller the spot size the higher the fluence.
Settings can be increased or decreased depending on the previous results and clients’ feelings during different sessions.
Rule of thump: Look for perifollicular edema which should appear few minutes after firing

– Phase of the hair growth cycle
Laser & IPL can only target the anagen.

At any given time, not all hairs are in the anagen phase.Therefore, multiple treatments are required to achieve the optimal appearance.

Timing between treatments is very important for optimal results with laser hair removal. It is important to pay for treatments one by one vs paying for packages of laser services up front. Different areas of the body have different hair growth cycles. In order to catch the most hair in the active cycle (or anagen phase) during your laser hair removal sessions, treatments should be scheduled according to the hair growth cycles.

In general, the best way to approach this is to use the regrowth of hair in the treated area as your guide… in other words, when a significant percentage of the hair starts growing back, return for the next treatment.
It could be as short as 4-6 weeks on the face, and as long as 8-12 weeks (or longer) for the legs. Bikini, chest, back, underarms, stomach etc. should be scheduled every 6-8 weeks, as for examples. These are different among different individuals.

Typically 6-8 sessions for each certain body area are recommended to catch each cycle of hair growth, although some people may be satisfied with their results sooner. Some may require more sessions. Following these guidelines should result in the greatest reduction of hair.

However, once desired results are achieved, many people come back annually for 1-2 treatment maintenance sessions. While in the maintenance phase, the ideal time to get a touch-up session is when you notice there are times when hair growth seems to be more aggressive. This is, as hair in the active growth phase is most effectively targeted.
Another recommended alternative would be to START WITH LASER treatment. Multiple laser sessions will be required. Once desired results are achieved by laser, then you may choose to FINISH WITH ELECTROLYSIS. This is the fastest way to achieve the optimal appearance (be it total removal or just thinning of the hair).

There is not a single "best’ laser device for hair removal on all patients. The list of machines available for laser hair removal includes the diode, alexandrite, and Nd:YAG laser, as well as IPL devices. Many different variations of these lasers are available from numerous manufacturers.

The best laser for laser hair removal for each person depends on his or her skin color, color of hair roots & diameters of hairs underneath the skin. Generally, lasers work the most effectively to remove dark-colored hair roots on light-color skin.
Based on real practices, the Alexandrite & diode lasers is the most effective laser for removing hair on lighter skin, whereas the Nd:YAG is the safest and best laser for more darkly pigmented skin. No any laser or IPL are effective in permanently reducing very blond or white hair. Neither, they are ineffective for people who have red hair.

For photos => please visit

Very good piece on laser basics, in my opinion and I find it very honest. Thank you for all your posts on laser.

Hairtell could really use a laser specialist to answer questions. It’s a wonderful privilege to serve the public here, but it may increase your laser business, as well.

I’m just going to agree with Dee Whleheartedly. Stick around please! There are a TON of laser questions and hasnt been anyone much but fenix or benton to anser them in years.


At least no one deleted my post here. My posts like this in forum .au they were all deleted within few hrs of posting.

Topic: Beginning basics of Laser & Laser Hair Removal (LHR)

Laser is light.

When u talking about light, you are also talking about colours.

colour = wavelength => They r the same thing in different contexts.

Please see the photo from the link and apply the principle of light absorption & reflection to different colours. Please note many lasers are invisible to human eyes. But the principle holds true even if we can see it or not with our naked eyes.

Different colours absorb different colours of light

Because Laser is light, to remove hair by laser we need to consider colours (or wavelengths) of both laser device & the natural colours of hair to be removed.

hair colour = melanin

see link =>

But melanin isn’t only found in hair. They r also in the skin cells (AKA keratinocytes) => Thus complication can happened.

To be continue…

You’ll find our most awesome moderator very unlikely to remove a post ever, unless it is most obvious spam and even then she rarely acts . You’re safe to express your opinions here. Heck they even put up with me and that’s saying alot!


Hair get destroyed by laser according to the following process. Any dark thingies (such pigments including brown &/or dark melanins) present in the skin & hair shaft absorb light of only certain wavelengths emitted by certain laser devices. Dark-colour objects turn laser light into heat and gives off such heat to surrounding that has no dark pigment such as hair follicles, hair stem cells and other skin cells. Thus laser heats & cooks the hair & reduces the chance of hair regrowth in the future.

For relevant photo =>

This is a very good explanation, especially of the dormant phase of the hair. Not all the follicles are growing at once, this sometimes causes people to think the hair removal didn’t work. It always takes multiple session to achieve complete hair removal.