LED light, explained: wavelength and dose

An LED mask comes with numbers: 625 nm, 12.93 mW/cm², 11.6 J/cm². Most people look at the colour and the photos first, and that is fine. The numbers are simply a precise way of saying three things: which colour, how strong and for how long. Once you can read them, you can compare spec sheets calmly and use your mask the way it was designed.

Three colours, one kind of light

LED stands for light-emitting diode: a small, efficient light that gives off one narrow colour. A mask places many of them close to the face, so the light falls evenly while you lie back. Red, yellow and blue are all the same kind of light. What changes from one colour to the next is the wavelength.

Wavelength: which colour

Wavelength is measured in nanometres (nm), billionths of a metre, and it is what your eye reads as colour. Blue sits at the short end of visible light, yellow in the middle and red at the long end. Just beyond red lies near-infrared, which the eye can no longer see. On GLAM LED Mask, blue is 415 nm, yellow 590 nm and red 625 nm.

A number is more precise than a word. “Red” on a box can mean many shades; “625 nm ±10 nm” tells you the narrow band every LED of that colour sits in.

Irradiance: how strong

Irradiance is how much light power reaches each square centimetre of skin, written in milliwatts per square centimetre (mW/cm²). Think of it as the brightness of the light where it meets your skin. It depends on distance, so it helps when a spec sheet says the values were measured.

Each colour comes from its own LEDs, so the values differ from colour to colour. On GLAM, red is 12.93 mW/cm², yellow 5.41 mW/cm² and blue 29.39 mW/cm².

Dose: strength multiplied by time

Dose is the total light energy that reaches each square centimetre of skin in one session. It is irradiance multiplied by time, written in joules per square centimetre (J/cm²). This is why minutes matter as much as brightness: the same light for twice as long is twice the dose. A mask that switches itself off keeps every session the same length, and so the same dose, without you watching the clock.

How to choose an LED mask

• Numbers in writing: the wavelength of every colour, the measured irradiance and the session length.
• A timer that switches the mask off, so every session is the same length.
• Visible light only, no UV, and a photobiological safety rating to IEC 62471.
• Built-in eye protection, and clear eye guidance in the user manual.
• A protocol you can keep: how many minutes, how often, one colour or several.
• Comfort: it should rest on your face and leave your hands free.
• Support after you buy, in your language.

A bigger number is not a goal in itself. Look for numbers you can check, and a routine that fits your evening.

How to use it: the 15-minute routine

• Cleanse and dry your face. Bare skin only: no serum, actives or sunscreen under the mask.
• Put the mask on and choose one colour.
• Lie back and relax. GLAM switches itself off after 15 minutes.
• The rest of your routine, serum and cream, comes afterwards.
• One session a day, and a different colour the next day.

Which colour when? Red is the evening classic, for skin that looks rested at the end of the day. Yellow suits reactive days, when your skin wants a calmer look. Blue is for blemish-prone skin, as part of a steady routine. If you cannot decide, simply rotate: red, yellow, blue, and start again.

Where other BEEA devices use light

In the other devices, light is one part of a routine that also uses current, warmth or vibration, and each device has its own protocol. The dose figures above apply to GLAM only.

• AURA 4-in-1 pairs a colour with each of its four modes, for example yellow 590 nm with GLOW, green with TONE and red 630 nm with PULSE.
• SCULPTA 4-in-1 uses red 633 nm, green 505 nm or blue 417 nm light, one per mode, together with EMS and controlled warmth along the jawline and neck.
• REMS REVIVE combines red 630 nm and near-infrared 850 nm light, at 3.3 mW/cm², with radiofrequency warmth.
• VITA Hair Comb uses a 650 nm low-level laser with 8 diodes, plus red LED light at 660 nm and blue at 465 nm, in its scalp routine. Never look straight into the laser or the LEDs.
• FACE GYM 3-in-1 closes its workout with an LED head that gives indicator-level light.