How many LEDs does a face mask really need?
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It is the question that decides the purchase, and the one product pages answer least well. One mask advertises eight wavelengths. Another highlights its number of diodes. A third says nothing at all. Here is what these figures mean, and which ones to look at.
What acts on the skin is a dose
Photobiomodulation does not work because a light is switched on. It works because a quantity of energy reaches the skin, at a useful wavelength, over a given time.
This quantity has a name and a unit: the dose, in joules per square centimetre. There is no mystery to the calculation:
irradiance (W/cm²) × time (s) = dose (J/cm²)
Our face mask delivers 40 mW/cm² at the skin surface. Over a 20-minute session, or 1,200 seconds: 0.040 × 1,200 = 48 J/cm².
This is the figure that should appear on every product page. It rarely does.
Why eight wavelengths are no better than four
A mask has a diode budget. The surface of a shell is finite, and each diode takes up a place that no other diode will take.
Spread that budget over eight wavelengths instead of four, and each wavelength gets half as many diodes. So half the power at the skin surface. So half the dose, for the same session time.
The number on the box goes up. The dose your skin receives goes down. This is not an opinion, it is a division.
Our choice: four wavelengths, 576 LEDs. Green 520 nm, which helps even out the complexion, amber 580 nm, which helps comfort skin prone to redness, red 630 nm, which helps smooth fine lines and revive radiance, and near-infrared 850 nm, which reaches deeper. Four documented, properly dosed wavelengths rather than eight advertised ones.
Density is only as good as its coverage
576 LEDs count for little if they stop at the cheekbones.
Many masks leave the perioral area uncovered: the upper lip, the corners of the mouth, the chin. This is precisely where vertical lip lines, nasolabial folds and marionette lines show.
Our shell extends below the nose and delivers the same wavelengths to this area as to the rest of the face. When you compare two masks, look at where the shell stops before you look at how many diodes it holds.
Origin, and why this one can be checked
South Korea is the industrial heart of at-home photobiomodulation. It is where diode density, wavelength calibration and 3D-moulded shells became a speciality rather than a selling point.
Our devices are made there. They carry KC certification, the Korean conformity scheme, in addition to the CE marking and the RoHS directive.
KC certification is worth pausing on: it can only be obtained through the Korean scheme. It is an origin that is proven, not merely claimed.
Take the product pages of the masks you are comparing and look for the country of manufacture. Many do not state it anywhere. It is information a brand readily publishes when it is proud of it.
The seven figures to check before you buy
- Irradiance, in mW/cm². Without it, the dose cannot be calculated. Its absence is an answer in itself.
- Dose per session, in J/cm². This is what the skin actually receives.
- The number of diodes, and the area covered. Both together, never one without the other.
- Wavelengths, in nanometres. Not in colours, in nanometres.
- No UV, and no blue light at a harmful wavelength.
- Country of manufacture and certifications. CE for Europe, KC for Korea, RoHS for substances.
- A study, with its number of participants, its duration and its protocol. A percentage without a protocol is not a result.
Our figures, since we ask others for theirs
- 576 LEDs across the whole face, from forehead to chin
- 4 wavelengths: 520, 580, 630 and 850 nm
- 40 mW/cm² at the skin surface, or 48 J/cm² per 20-minute session
- Made in South Korea · CE · KC · RoHS
- No UV, no blue light, no heat
- +13.6% skin density at 3 weeks, mask combined with a cream, clinical study of 20 people
Clinical study run by a third-party laboratory · 20 people aged 25 and over · face · 3 weeks, one 20-minute session every evening · mask combined with a cream · instrumental measurements before / after, no control group · no side effects reported. Irradiance and dose: values stated by the manufacturer. Results vary with skin type and regular use. LED light therapy device for personal cosmetic use: it is not a medical device and does not replace dermatological advice.
Twenty minutes, four to five evenings a week
One last figure, which counts as much as the others: consistency. Photobiomodulation works as a course. Our recommendation fits on one line: 20 minutes per session (10 for the amber and green programmes), 4 to 5 evenings a week for 4 weeks, then 2 to 3 for maintenance. The session comes first, on clean, dry skin, and your skincare right after.
This is not the protocol of the study cited above, which was run every evening for 3 weeks with the mask combined with a cream. A study protocol is there to measure, not to build your routine.
A very dense mask used once a month will help little. A properly dosed mask, used four to five evenings a week, has time to help the skin.