How does laser hair removal work?

[LightningInAJar]

TL;DR Summary

What is the mechanism that makes laser hair removal work?

How exactly does laser hair removal work? I have heard it has to do with the hair pigment against skin color contrast. But what about that makes a laser target the hair root? Maybe someone needs to explain how lasers and wavelengths work to me. Does the laser "ignore" the skin and hair above the skin somehow?

 

[phinds]

What research have you done on this so far? What have you found out?

 

[DaveC426913]

Here is your answer:
https://tinyurl.com/wa8cdh5s

 

[LightningInAJar]

What research have you done on this so far? What have you found out?

Just YouTube videos mostly. Also I am currently getting laser hair removal but I don't honestly think the practitioner fully understands it. As it turns out in New York State you don't need a license or certification to do laser hair removal or electrolysis. So that was a surprise. I intend to ask my dermatologist next time I see them, but in the mean time am trying to get an idea outside of time that can be billed to my insurance. Lol.

 

[phinds]

Just YouTube videos mostly

And what did you find out? Why are you asking us when the answer is SO readily available on the Internet? See post #3 and follow up.

 

[berkeman]

Here is your answer:
https://tinyurl.com/wa8cdh5s

The problem with that link (while humorous) is that it vectors to google.gprivate.com, and clicking on the search results sends me off into the advertisement weeds. Probably better just to admonish the OP to do the search themself.

 

[DaveC426913]

...it vectors to google.gprivate.com, and clicking on the search results sends me off into the advertisement weeds...

TIL.

 

[DaveC426913]

Just YouTube videos mostly. Also I am currently getting laser hair removal but I don't honestly think the practitioner fully understands it. As it turns out in New York State you don't need a license or certification to do laser hair removal or electrolysis. So that was a surprise. I intend to ask my dermatologist next time I see them, but in the mean time am trying to get an idea outside of time that can be billed to my insurance. Lol.

Melanin, which is found at the root, is dark. It absorbs more laser light than the surrounding tissue. It is converted to heat.

 

[berkeman]

it vectors to google.gprivate.com

Here is the Mayo Clinic link that I was trying to get to via that link: https://www.mayoclinic.org/tests-procedures/laser-hair-removal/about/pac-20394555

Hopefully it helps the OP with their treatment (Tx).

 

[phinds]

Well, once again we have someone who suckered us into doing his research for him.

 

[LightningInAJar]

Here is your answer:
https://tinyurl.com/wa8cdh5s

Yes that essentially what I know. But why would the laser effect only the hair colorant in the root area and not anywhere along its length?

I am asking because some of my hair has grayed. I was curious if anyone discovered a way to flip the contrast if the hair is lighter than the skin.

 

[DaveC426913]

... why would the laser effect only the hair colorant in the root area and not anywhere along its length?

What makes you think it doesn't?

The point of the laser is to get sufficient light to be absorbed at the root (through the relatively transparent dermal layers), where it can do its damage.

Who cares what it does to the shaft of the hair?

 

[LightningInAJar]

What makes you think it doesn't?

The point of the laser is to get sufficient light to be absorbed at the root (through the relatively transparent dermal layers), where it can do its damage.

Who cares what it does to the shaft of the hair?

Can in theory light color be targeted against darker background? Maybe a different wavelength can get that effect?

 

[DaveC426913]

Can in theory light color be targeted against darker background? Maybe a different wavelength can get that effect?

"Darker background"? What do you mean?

 

[Tom.G]

@LightningInAJar, I think you are missing a piece of background information on this.

Things that are light in color appear that way because they reflect much of the incoming light.

Things that are dark appear that way because they absorb much of the incoming light, not reflecting it to the surrounding environment and to our eyes.

LASERs are readily available with power outputs from less than 1 milliWatt, to a few thousand Watts.

It was mentioned that the hair root is darker than the hair itself and darker that than the skin.

Putting all of this together, the hair root absorbs more LASER light - therefore gets hotter than the surrounding tissue - and is burned to death - with minimal damage to surrounding tissue.

Hope this helps.

Cheers,
Tom

 

[LightningInAJar]

"Darker background"? What do you mean?

I mean if my skin is darker than my white hairs?

 

[LightningInAJar]

@LightningInAJar, I think you are missing a piece of background information on this.

Things that are light in color appear that way because they reflect much of the incoming light.

Things that are dark appear that way because they absorb much of the incoming light, not reflecting it to the surrounding environment and to our eyes.

LASERs are readily available with power outputs from less than 1 milliWatt, to a few thousand Watts.

It was mentioned that the hair root is darker than the hair itself and darker that than the skin.

Putting all of this together, the hair root absorbs more LASER light - therefore gets hotter than the surrounding tissue - and is burned to death - with minimal damage to surrounding tissue.

Hope this helps.

Cheers,
Tom

Maybe white hairs absorb more in the invisible spectrum than skin does?

 

[DaveC426913]

I mean if my skin is darker than my white hairs?

It's the root, where all the melanin is, that counts. It doesn't matter what happens to your hair shaft.

In fact, plausibly, hair shafts that are white block less light to the root.

 

[vela]

Maybe white hairs absorb more in the invisible spectrum than skin does?

That's possible in principle. The idea behind laser hair removal is to use the wavelength that damages the hair the most effectively while leaving the surrounding tissue unharmed. Other wavelengths could have the opposite effect, damaging the skin while leaving the hair unscathed. That's why a laser is used, since lasers produce light in a narrow range of wavelengths.

If your actual question is "can laser hair removal get rid of my gray hairs?" the answer is probably no.

You might find this site helpful in your research: https://www.hairfacts.com/