#5 The Serum

#5 The Serum

30ml

$180.00

Skin-Refining Serum

Clarity is the Fifth Pillar of Skin Health.

The Story

A potent revival of absolute clarity.

This sophisticated skin-refining serum recalibrates skin’s pH balance for a more even, smoother appearance. As skin rejuvenation is optimised and irritation calmed, skin looks and feels immediately renewed, resurfaced and deeply luminous.

The Promise

Skin tone and texture are refined, and clarity is restored.

Recalibrates skin pH to a youthful acidic level.

Clarifies skin to promote a more even appearance.

Hydration levels are augmented to visibly smooth fine lines.

Skin looks and feels softer and more radiant.

The Results

At RATIONALE, we’re pleased to report the proportion of participants who observed the following improvements in their skin after use of #5 The Serum* :

81% reported ↑ Radiance and Brightness
91% reported ↑ Even tone
75% reported ↑ Firmness
*Based on a 28-day trial with 21 participants

The Clarity Actives

A Complex of Skin Identical Alpha Hydroxy Acids (including Lactic + Citric Acid) refines skin tone and texture while enhancing skin radiance by encouraging optimal desquamation processes to reveal a clearer, more balanced complexion. By recalibrating skin back to acidic levels, AHAs support cellular renewal and connective tissue synthesis, while amplifying skin firmness and hydration.

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Opposite: ‘Alpha Hydroxy Acids’
Illustration by Jessie Milligan

Ingredients: Aqua (Water), Ethoxydiglycol, Vaccinium Myrtillus Fruit Extract, Dimethyl Isosorbide, Salicylic Acid, Lactic Acid, Saccharum Officinarum (Sugar Cane) Extract, Glycerin, Citrus Aurantium Dulcis (Orange) Fruit Extract, Citrus Limon (Lemon) Fruit Extract, Sodium Levulinate, Acer Saccharum (Sugar Maple) Extract, Diutan Gum, Melaleuca Alternifolia (Tea Tree) Leaf, Sodium Anisate, Mentha Australis Leaf Extract, Butylene Glycol, Santalum Spicatum (Sandalwood) Seed Oil, Citrus Aurantium Dulcis (Orange) Oil, Citrus Aurantium Bergamia (Bergamot) Leaf Oil, Juniperus Mexicana Oil, Pelargonium Graveolens Oil, Citrus Aurantium Amara (Bitter Orange) Flower Oil, Eugenia Caryophyllus (Clove) Leaf Oil, Citrus Aurantium Bergamia (Bergamot) Fruit Oil, Citrus Grandis (Grapefruit) Peel Oil, Citrus Limon (Lemon) Peel Oil, Litsea Cubeba Fruit Oil, Pentylene Glycol, Magnesium Aspartate, Zinc Gluconate, Citrus Australasica Fruit Extract, Sodium Benzoate, Citric Acid, Copper Gluconate, Potassium Sorbate, Glycine, Serine, Glutamic Acid, Aspartic Acid, Leucine, Alanine, Lysine, Arginine, Tyrosine, Phenylalanine, Proline, Threonine, Valine, Isoleucine, Histidine, Limonene, Citral, Linalool, Citronellol.

The Clarity Actives

Salicylic Acid is a lipid-soluble Beta Hydroxy Acid which enhances skin clarity and texture by decongesting pores and calming irritation and redness.

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Side arrow

Opposite: ‘Alpha Hydroxy Acids’
Illustration by Jessie Milligans.

Ingredients: Aqua (Water), Ethoxydiglycol, Vaccinium Myrtillus Fruit Extract, Dimethyl Isosorbide, Salicylic Acid, Lactic Acid, Saccharum Officinarum (Sugar Cane) Extract, Glycerin, Citrus Aurantium Dulcis (Orange) Fruit Extract, Citrus Limon (Lemon) Fruit Extract, Sodium Levulinate, Acer Saccharum (Sugar Maple) Extract, Diutan Gum, Melaleuca Alternifolia (Tea Tree) Leaf, Sodium Anisate, Mentha Australis Leaf Extract, Butylene Glycol, Santalum Spicatum (Sandalwood) Seed Oil, Citrus Aurantium Dulcis (Orange) Oil, Citrus Aurantium Bergamia (Bergamot) Leaf Oil, Juniperus Mexicana Oil, Pelargonium Graveolens Oil, Citrus Aurantium Amara (Bitter Orange) Flower Oil, Eugenia Caryophyllus (Clove) Leaf Oil, Citrus Aurantium Bergamia (Bergamot) Fruit Oil, Citrus Grandis (Grapefruit) Peel Oil, Citrus Limon (Lemon) Peel Oil, Litsea Cubeba Fruit Oil, Pentylene Glycol, Magnesium Aspartate, Zinc Gluconate, Citrus Australasica Fruit Extract, Sodium Benzoate, Citric Acid, Copper Gluconate, Potassium Sorbate, Glycine, Serine, Glutamic Acid, Aspartic Acid, Leucine, Alanine, Lysine, Arginine, Tyrosine, Phenylalanine, Proline, Threonine, Valine, Isoleucine, Histidine, Limonene, Citral, Linalool, Citronellol.

The Clarity Actives

Australian Botanicals have the capability to support skin clarity while reducing a feeling of sensitivity.

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Side arrow

Opposite: ‘Alpha Hydroxy Acids’
Illustration by Jessie Milligan

Ingredients: Aqua (Water), Ethoxydiglycol, Vaccinium Myrtillus Fruit Extract, Dimethyl Isosorbide, Salicylic Acid, Lactic Acid, Saccharum Officinarum (Sugar Cane) Extract, Glycerin, Citrus Aurantium Dulcis (Orange) Fruit Extract, Citrus Limon (Lemon) Fruit Extract, Sodium Levulinate, Acer Saccharum (Sugar Maple) Extract, Diutan Gum, Melaleuca Alternifolia (Tea Tree) Leaf, Sodium Anisate, Mentha Australis Leaf Extract, Butylene Glycol, Santalum Spicatum (Sandalwood) Seed Oil, Citrus Aurantium Dulcis (Orange) Oil, Citrus Aurantium Bergamia (Bergamot) Leaf Oil, Juniperus Mexicana Oil, Pelargonium Graveolens Oil, Citrus Aurantium Amara (Bitter Orange) Flower Oil, Eugenia Caryophyllus (Clove) Leaf Oil, Citrus Aurantium Bergamia (Bergamot) Fruit Oil, Citrus Grandis (Grapefruit) Peel Oil, Citrus Limon (Lemon) Peel Oil, Litsea Cubeba Fruit Oil, Pentylene Glycol, Magnesium Aspartate, Zinc Gluconate, Citrus Australasica Fruit Extract, Sodium Benzoate, Citric Acid, Copper Gluconate, Potassium Sorbate, Glycine, Serine, Glutamic Acid, Aspartic Acid, Leucine, Alanine, Lysine, Arginine, Tyrosine, Phenylalanine, Proline, Threonine, Valine, Isoleucine, Histidine, Limonene, Citral, Linalool, Citronellol.

The Ritual

Smooth gently over face, neck, décolletage and backs of hands each evening. 

Follow with your RATIONALE Essential Six formulations for night. 

To discover how to introduce this formulation into your RATIONALE Ritual, connect with our Team of Online Skin Consultants. 

Discover More

The Research

The pH of the skin’s outermost layer, the Stratum Corneum, is vital to complexion health, vitality and beauty.

The ideal state of the Stratum Corneum is acidic, as these conditions maintain the upregulation of enzymes critical to the synthesis of collagen and elastin (skin connective tissues that provide skin structure and firmness), as well as helping to prevent collagen breakdown, sensitivity, breakouts and infection.

Throughout life, skin becomes more alkaline as a result of intrinsic ageing and environmental damage. This leads to an upregulation of enzymes that break down skin connective tissues, leading to premature ageing, wrinkles and sagging.

Recalibrating and maintaining the acidic pH of skin is possible via a nightly regime of topically applied hydroxy acids which help to reverse the effects of facial ageing and environmental damage.