Just got my Silk'N. Have a few questions.

Hair Removal Methods Do-It-Yourself Laser/IPL
#1

Hi all,
A few questions regarding Silk’N. First of, I’m female, pale white skin, brown hair.

I just used it once so far, on my legs, and have a few questions:

  1. What should I expect during the next couple of weeks - should I see any hair falling off? Will any hair grow during this time (in which case I’ll have to shave it)?
  2. If I have hair growth between treatments - can I use my Silk-Epil rotary tweezer, or better if I just shave?
  3. What level should I use on armpits and crotch? Are there any special side-effects in these areas? (legs went through fine).
    Thanks!
#2

One question I can answer is DON’T use a rotary tweezer. No tweezing at all. Shaving is fine. I hope you have success with this product, but… I’m doubtful that it will meet your expectations???

#3

First, I have to say that I hope you realize that this product will NOT provide you with permanent hair removal. The advertising is misleading, so just wanted to point that out in case that’s what you’re hoping to get out of it. It can, however, provide you with temporary longterm removal when used properly.

Now, I’m also a bit concerned. Are there NO instructions provided? These questions are basic and should really be included with the product.

You should treat at highest settings your skin can handle without burning. Treated hair should fall out within 3 weeks. You can shave, but it’s better not to during these 3 weeks as it can slow down shedding. Afterwards, you can shave all you want, but you can’t use methods that remove hair with the root (i.e. waxing, epilators, tweezing, etc).

By the way, professional treatments with a powerful laser on armpits and bikini only cost $50-150 per treamtent and you would be done after 6-8 treatments spaced 2 months apart. It would likely be cheaper and definitely more effective and will produce permanent results compared to using this thing which costs $700+ and requires constant $60-80 lamp replacements.

#4

So here’s my take on the Silk’n or any home-based light hair removal product. I’m coming from an engineering standpoint so this may bore some people. You need several things to remove hair permanently using a light source. You need enough energy (fluence) in the right amount of time (pulse width). Epidermal and follicular tissues have certain thermal relaxation times (TRT). The pulse width should be longer than the TRT of the epidermis and shorter than the TRT of the follicle. Estimation of the epidermal TRT is 3-7 milliseconds. The follicle TRT is estimated at 10-100 milliseconds. Minimum fluence to achieve any permanent follicle damage is around 15J/cm2. The Silk’n, being as small as it is, cannot have enough power to effect permanent hair removal. It will also be missing an important component, a pulse forming network (PFN). Without a PFN the discharge of a xenon strobe happens way too fast. The epidermis is heated up before the follicle resulting in nothing more than surface heat. You can disable a hair follicle for a little while this way but you’ll never stop it from coming back. The Silk’n will fail on two counts. It only has 5J/cm2 fluence (way too little) and a pulse width way too short. Most manufacturers of IPL devices also severely overestimate the power output. The spectra of xenon has 32% of it’s output below 600nm. This light is filtered for hair removal so you only have 68% left. About 7% of the remaining light output is too far into the infrared to do any good so you are left with only 61% being useful for hair removal. My guess would be that the output of the Silk’n is closer to 3J/cm2. On a side note, the Tria has enough fluence but the 300-600 millisecond pulse width is about 10X the TRT of the follicle. This renders the Tria useless for permanent hair removal. If the general public had any idea how much energy it takes to remove hair with light they would laugh when they see a home product like these. To give you an idea, a fully charged bank of capacitors in a 50J/cm2 IPL with a 5 square centimeter spot size has enough energy to kill 20 people. This energy is discharged every flash. A battery pack would have to be the size of a large suitcase to last a few hundred flashes. A tiny toy like the Silk’n or a battery powered Tria are never going to get the job done. My recommendation to anyone who has purchased one of these products is to return it ASAP before the warranty runs out. Since these are advertised as a replacement to professional laser treatments, in my opinion, Andrea needs to put them on the same page with electric tweezers and transdermals.

#5

galvaniczap,
Tria has a pulsewidth range of 125-600 ms, and a fluence range of 6-22 joules. It is not clear if the lower pulse width go with higher fluence to provide a more powerful treatment. Does anyone know?

I have used Tria about 6 times so far and it hurts a lot on the highest fluence of 22 joules. So far I have had good result on my hand and my arm, with no regrowth on my hand for about 2 weeks, and partial regrowth and shedding on my arm since my treatment three weeks ago. I don’t know if any of this will lead to permanent hair reduction, but I remain hopeful.

Don’t buy this product if you cannot tolerate intense pain.

#6

SAK,

If you look at the ratio of 6:125 and 22:600 they are pretty close when you divide them out. Without hooking one up to an infrared photodetector and my oscilloscope I can’t say for sure but it seems pretty linear to me. In other words, the longer it’s on the more it puts out. A better way to look at the output of a laser hair removal system is not to look at Joules but Joules per millisecond. A Lightsheer system puts out about 2 Joules per millisecond whereas the Tria puts out about .04 per millisecond. The Tria is 50X LESS powerful than a professional laser. It will cause some skin discomfort and partial hair dormancy but it will never remove hair permanently. My original advice stands, send it back and get a refund. This is simply a way to separate you from your money, not your hair from your body.

#7

galvaniczap,
Thanks for an interesting look at the efficacy of laser through the joules per millisecond metric.

I have had one treatment with a commercial Yag on my underarms at 24J and 20ms pulse width with excellent result so far. Using your metric, that is about 1.2 j/ms. As I was able to tolerate the pain well, I may try a setting with higher joules(32J)and a lower pulse width(16)–an effective metric of 2 j/ms.

It seems to me that lower pulse width may not be appropriate for my type 4 skin.

#8

To treat at 25J with the Tria, you can only use the 600ms pulse width. And treating with anything under 25J is pretty useless for permanent results.

24J even with 20ms is a pretty low setting on a Yag and is usually too low for a type IV. You should really test your skin at much more efficient settings asap to avoid wasting money.

#9

LAgirl,
I will try out 32J and 16ms for my second treatment on my underarms scheduled in January.

For type 4 on a YAG, would it be possible to go down to 10ms? Even lower?

#10

SAK,
Who knows what information or programming was put into this but it is fun to play with.

http://www.gulfdoctor.net/model/lhr.htm

Here’s the white paper on it too:

http://www.ijdvl.com/article.asp?issn=0378-6323;year=2009;volume=75;issue=4;spage=383;epage=387;aulast=Eapen

#11

galvaniczap,
What is the difference between pulse width and pulse duration as laid out in the tool? I have seen discussion where these are considered interchangeable terms.

Thanks for an interesting link.

#12

I came across an article which explores the concept of thermal damage time(and not thermal relaxion time) of hair to support effectiveness of long pulse width lasers. The article suggests that hair’s thermal damage time can range from 170 to 1000 ms.

They use a modified diode to conduct their study, which concludes that the optimal setting is around 46J and 400ms pulse duration.

Maybe there is hope for Tria. The link to article:

#13

Another study(using Yag laser) shows that pulse width of 50 ms was effective in reducing hair.

#14

Another study showing that longer pulse durations are effective in reducing hair.

#15

SAK,
The laser simulation tool has the pulse duration and spot size set to constant values and you can’t change them. The difference betweeen pulse duration and pulse width is as follows. Lasers can be used in single or multiple pulse modes. If used in multiple pulse mode, you have an overall pulse duration and individual pulse widths inside of the whole pulse duration.

As far as the listed studies go, you have to follow the paper trail. I wouldn’t be surprised if these doctors weren’t on somebody’s payroll who were trying to market a very long pulse diode laser. For the right price you can get a doctor to say or do most anything. This study was almost 8 years old. There would have been professional machines made using this type of system because it would have been much cheaper. It’s simple to put out that many Joules if you can do it over the time span of .5 to 1 second. Power supplies are tiny and heat removal issues are minimal. They don’t make these kinds of lasers for hair removal because they don’t work. If they did every clinic would be using a $500 laser instead of a $50,000 one. There still is no hope for the Tria.

#16

Galvaniczap makes a great point at the end, which we always try to point out. There is a reason that clinics don’t use a $500 machine. If it actually worked, they would make a lot more money compared to spending $50K+ on a professional machine.

In terms of your Yag settings, you need to test your skin. Most Yags don’t go lower than 10ms. That’s the lowest for most. Most go a lot higher on the joules though.

#17

LAgirl,
I am planning to switch to a provider who has a GentleMax, which I believe has a pulse range of 0.25-300ms, with the added benefit of spot sizes upto 18mm.

My one treatment on a Yag was at 24J, 20ms, with a spot size of 9mm(?). I had few red bumps after the treatment on my armpits, and excellent shedding with no regrowth in 5 weeks since the treatment.

Would going from 9mm to 18mm require a substantial reduction in joules? How much is 24J with 18mm spot size equivalent to in fluence with a 9mm spot size? Is there a simple rule of thumb or formula that one can use?

Btw, I returned my Tria today as I wasn’t very confident about its effectiveness. I will update with results in about 3-6 months on select areas on my arm and hand where I used it extensively.

#18

9mm? Why did they go so low? With that low of a spot size, 24J on a Yag is really very weak. It’s impossible to answer your question without knowing the pulse width used since it’s adjustable on the Yag.

#19

I have cleared up my confusion on joules setting and spot size. As laser energy is measured in terms of joules/cm^2, a change in spot size should not require any change in joules.

A larger spot size will cover a larger area at the same intensity(j/cm^2). Furthermore, it has been pointed that a larger spot size is more effective at hair reduction.

#20

That’s not the case since there are other factors involved such as depth of penetration.