12.2 Galvanic Current: Iontophoresis & Desincrustation

12.2 Galvanic Current: Iontophoresis & Desincrustation

CIDESCO Exam Tip: CIDESCO examiners frequently test candidates on the exact chemical reactions occurring under the positive anode versus the negative cathode during galvanic treatments. Memorize the chemical products formed (Hydrochloric Acid vs Sodium Hydroxide), their biological tissue effects, and the precise phoresis rules governing iontophoresis product polarity matching.

Constant Direct Current, historically termed Galvanic Current after Luigi Galvani, is a low-voltage, continuous direct current that flows uninterruptedly in a single direction. Unlike alternating currents that produce thermal or mechanical effects, galvanic current produces profound chemical changes within skin tissues through a process known as electrolysis. By passing direct current through the electrolyte-rich fluids of human skin, water (H₂O) and dissolved salts (NaCl) dissociate into active ions, creating distinct polar reactions at the positive and negative electrodes.

Chemical Principles of Galvanic Current & Polar Reactions

When galvanic current passes through cutaneous tissue, positively charged ions (cations, such as Na⁺) migrate toward the negative electrode (cathode), while negatively charged ions (anions, such as Cl⁻) migrate toward the positive electrode (anode).

Reactions at the Cathode (Negative Pole, -)

As electrons exit the cathode into tissue fluids, water and sodium chloride undergo electrolysis, generating Sodium Hydroxide (NaOH), a potent alkali, along with hydrogen gas (H₂). The introduction of sodium hydroxide produces specific physiological responses termed Anaphoresis:

• Alkaline pH Shift: Increases tissue alkalinity.
• Keratolytic Tissue Softening: Softens protein structures, keratin, and epidermal intercellular cement.
• Follicular Ostia Dilation: Opens pore openings, relaxing hair follicle walls.
• Vascular Vasodilation: Increases blood flow and local hyperemia.
• Nerve Stimulation: Excites cutaneous sensory nerve endings.

Reactions at the Anode (Positive Pole, +)

At the anode, chloride ions lose electrons to form Hydrochloric Acid (HCl) and oxygen gas (O₂). The accumulation of hydrochloric acid produces physiological responses termed Cataphoresis:

• Acidic pH Shift: Decreases tissue alkalinity, restoring the skin's protective acid mantle.
• Tissue Hardening & Astringency: Firms protein structures and tightens epidermal tissue.
• Follicular Ostia Constriction: Constricts and closes pore openings.
• Vascular Vasoconstriction: Decreases local blood flow, reducing erythema and inflammation.
• Nerve Sedation: Soothes and calms irritable sensory nerve endings.

Summary of Galvanic Polar Reactions

Desincrustation: Mechanics & Treatment Protocol

Desincrustation is a deep-cleansing galvanic procedure designed to soften and liquefy hardened sebum plugs (comedones) in oily, congested, or acne-prone skin.

The Biochemical Process of Saponification

During desincrustation, an alkaline liquid solution containing sodium carbonate, sodium bicarbonate, or sodium chloride dissolved in purified water is applied to the skin. The therapist places the active negative electrode (cathode) on the client's face, while the client holds the passive positive electrode (anode) wrapped in a damp conductive sponge.

As galvanic current flows, sodium hydroxide (NaOH) forms directly under the active cathode. The alkali reacts chemically with the free fatty acids and triglycerides present within follicular sebum. This chemical reaction is called saponification—the conversion of fatty esters into liquid soap. Saponification turns hard, solid comedonal sebum into a water-soluble soap solution, allowing the therapist to easily extract stubborn blackheads and clear congested follicles.

Desincrustation Protocol Steps

1. Cleanse client skin thoroughly and conduct tactile sensation testing.
2. Apply alkaline desincrustation lotion or saturate a cotton gauze mask with the solution.
3. Hand the client the dampened positive passive electrode.
4. Place the active negative electrode on the client's skin before establishing current.
5. Slowly increase intensity to a comfortable level (0.5 mA to 1.5 mA for facial application).
6. Glide the active electrode continuously over congested areas for 3 to 5 minutes.
7. Reduce current to zero, turn off machine, and remove remaining desincrustation lotion.
8. Perform manual extractions while sebum remains liquefied.
9. Polarity Reversal (Cataphoresis): Apply an acidic toner, switch the active electrode to positive (anode), and run current for 1 to 2 minutes at low intensity to neutralize remaining alkali, close pores, and restore skin pH.

Iontophoresis: Principles & Phoresis Rules

Iontophoresis is the process of introducing water-soluble, ionized active substances deep into the living layers of the epidermis using galvanic current.

The Electrostatic Rule of Phoresis

Iontophoresis operates on the fundamental physical law of electrostatics: like electrical charges repel each other, while opposite charges attract.

To drive an active cosmetic ingredient into the skin:

• Positively Charged Actives (Cations): Must be placed under the Active Positive Electrode (Anode). The positive anode repels the positive ions, pushing them deep into the cutaneous tissue.
• Negatively Charged Actives (Anions): Must be placed under the Active Negative Electrode (Cathode). The negative cathode repels the negative ions into the tissue.

Crucial Requirement: Formulations used for iontophoresis must be water-soluble and ionized. Oil-based creams, lipid serums, or un-ionized molecules cannot carry an electrical charge and will obstruct current flow.

Operational Safety & Burn Prevention

Galvanic current carries a risk of chemical burns due to localized acid or alkali accumulation under electrodes. Therapists must enforce the following safety rules:

• Maximum Current Density: Facial intensity must never exceed 2.0 mA (typically 0.5–1.5 mA). Body intensity should not exceed 5.0 mA.
• Continuous Movement: The active electrode must remain in continuous, smooth motion to prevent localized chemical pooling.
• Sponge Saturation: Passive electrodes must be fully wrapped in thick, evenly dampened sponges. Exposed bare metal touching client skin will cause immediate, severe chemical burns.
• Metallic Taste: Inform clients that a mild metallic taste is normal during facial galvanic procedures due to electrolysis of trace minerals in saliva.