Glow Glossary

Gua Sha

A traditional East Asian healing technique using a smooth stone tool to stroke the skin. Facial gua sha is an adapted, significantly gentler version focused on lymphatic drainage and circulation, holding the tool at 15–45° in upward, outward strokes.

LED Phototherapy

The application of specific light wavelengths to skin tissue. Red light (630–660nm) penetrates to the dermis and is associated with collagen stimulation. Near-infrared (810–850nm) penetrates deeper for tissue repair. Blue light (~415nm) has antibacterial properties against P. acnes bacteria.

IPL (Intense Pulsed Light)

Broad-spectrum light technology (500–1200nm) used primarily for hair reduction and skin rejuvenation. Works by targeting melanin in hair follicles — most effective on light skin with dark hair due to the contrast requirement.

Lymphatic Drainage

The lymphatic system collects interstitial fluid and returns it to the bloodstream via lymph nodes. The system has no pump — it relies on muscle contractions and manual stimulation. Facial massage techniques encourage fluid movement toward neck and clavicular lymph nodes.

Photobiomodulation (PBM)

The broader scientific term for LED light therapy, encompassing all therapeutic applications of non-ionizing light. PBM primarily involves mitochondrial stimulation (cytochrome c oxidase), increased ATP production, and downstream effects on collagen synthesis.

Sonic Pulsation

High-frequency vibration technology used in facial cleansing devices. Sonic devices typically operate at 300+ oscillations per second, creating fluid dynamics that help loosen debris from the skin surface. Cleaning advantage over manual methods is well-documented.

Gel Polymerization

The chemical curing process when UV or LED light causes photoinitiators in gel nail product to trigger monomer bonding into a hard polymer network. Adequate irradiance at the correct wavelength is required for complete polymerization through the full depth of the gel layer.

Irradiance

The power of light energy delivered per unit area, measured in milliwatts per square centimeter (mW/cm²). In LED therapy, irradiance determines how quickly a therapeutic dose is delivered. Higher irradiance enables shorter session times for equivalent biological effect.

Fitzpatrick Scale

A classification system for human skin phototype based on response to UV exposure. Ranges from Type I (very fair, always burns) to Type VI (deep brown-black, never burns). Critical for determining IPL safety and appropriate intensity settings.

Fibroblast

The primary cell type responsible for producing collagen, elastin, and hyaluronic acid in the dermis. Many device treatments claim to stimulate fibroblast activity as their anti-aging mechanism. Well-designed studies use fibroblast proliferation as an objective outcome measure.

Stratum Corneum

The outermost layer of the epidermis, composed of dead skin cells. Acts as the primary barrier against water loss. Exfoliation techniques including cleansing brushes act on this layer. Over-exfoliation impairs barrier function and leads to increased sensitivity.

Sebaceous Gland

Glands in the skin that produce sebum. Overactive sebaceous glands contribute to oily skin and acne. Cleansing brushes and IPL treatment of certain wavelengths can influence sebaceous gland activity and pore appearance over time.

Erythema

Redness of the skin caused by increased blood flow to superficial capillaries. Mild transient erythema after tool use lasting under 30 minutes is generally normal. Persistent erythema with warmth or itching may indicate irritation or inappropriate device intensity.

Anagen Phase

The active growth phase of the hair follicle cycle, during which IPL and laser hair removal are effective. Only follicles in the anagen phase can be targeted — approximately 30–40% of follicles at any given time. This explains why multiple IPL sessions over weeks are required for complete results.