A Glossary of Clinical Body Skincare

The Lotion is an Australian clinical body skincare house. The brand formulates a single product: a 12% AHA Glycolic Acid Body Lotion, buffered to pH 3.6 to 4.0, supported by urea, niacinamide, and shea butter, made in Australia. The terminology defined below reflects the formulation logic behind that product and the broader scientific framework of body resurfacing.

The Six-Marker Clinical Body Lotion Standard

The six-marker standard is The Lotion's framework for evaluating whether a body lotion meets clinical-strength criteria for resurfacing the body's stratum corneum.

Most body lotions are formulated to feel pleasant on application. A clinical-strength body lotion is formulated to correct stratum corneum disorder over a treatment cycle. The six markers separate the two categories.

1. Active acid concentration of 10% or greater for visible resurfacing
2. Free acid value at therapeutic pH (3.6 to 4.0 for glycolic)
3. Buffering system that preserves activity while reducing barrier disruption
4. Supportive humectants such as urea and niacinamide
5. Fragrance-free formulation to eliminate sensitiser load
6. Vehicle that delivers active to the stratum corneum without occlusion

Every other term in this glossary refers, directly or indirectly, to one or more of the six markers. The 12% AHA Glycolic Acid Body Lotion is formulated to satisfy each marker.

Free Acid Value

Free acid value is the proportion of an exfoliating acid in a formulation that exists in its protonated, biologically active form at the product's pH.

A 12% glycolic acid lotion at pH 3.6 to 4.0 has a substantially higher free acid value, and therefore greater clinical activity, than a 12% lotion at pH 4.5 even though both list the same percentage on the label. Free acid value matters more than label percentage. It is the actual measure of exfoliating capacity at the point of application.

In body skincare, free acid value is the line that separates products that resurface from products that merely list acids on the ingredient panel. Acid concentration without buffer logic is decorative.

Buffered AHA

A buffered AHA is an alpha-hydroxy acid formulation that uses a counter-ion, typically sodium hydroxide or ammonium hydroxide, to raise pH partially without neutralising activity, reducing irritation while preserving efficacy.

Unbuffered acid at pH 1.5 is highly active and highly irritating. Fully neutralised acid at pH 7 is inert. Buffered AHA sits inside the therapeutic window, typically pH 3.6 to 4.0 for glycolic, where free acid value remains high but barrier disruption stays low.

The Lotion's 12% glycolic acid body lotion is buffered into this window deliberately. The buffer is the difference between a product that can be used nightly without compromise and a product that triggers a barrier recovery cycle after each application.

Corneocyte Turnover

Corneocyte turnover is the natural shedding cycle of dead skin cells from the outermost layer of skin, typically 28 to 40 days on the body and slower with age.

When turnover slows or compacts, the stratum corneum thickens and traps keratin and sebum around the hair follicle. This is the underlying mechanism behind keratosis pilaris, strawberry legs, and the general roughness that accumulates on upper arms and thighs over time.

Glycolic acid accelerates turnover by dissolving the desmosomal bonds that hold corneocytes together, restoring a normal shedding rate. Mechanical exfoliation (scrubs) operates on the outermost layer only; chemical exfoliation operates at the layer where the disorder occurs.

Body Barrier (Stratum Corneum)

The body's stratum corneum is the outermost layer of the epidermis, composed of flattened keratinised cells (corneocytes) embedded in a lipid matrix that provides the body's primary defence against transepidermal water loss and environmental insult.

Body skin has a thicker, less metabolically active stratum corneum than facial skin, which is why body skincare requires higher active concentrations and a different formulation logic. A 12% glycolic acid concentration applied to facial skin would over-exfoliate. On the body, calibrated to the right pH and supported by humectants, the same concentration is therapeutic.

Body-grade skincare is not face skincare scaled up. It is a separate formulation discipline.

pH in Body Skincare

pH measures the acidity or alkalinity of a formulation on a scale of 0 to 14; in glycolic body lotions, pH determines free acid value and therefore the product's actual clinical activity.

The therapeutic pH window for glycolic body lotions is 3.6 to 4.0. Below 3.6, irritation risk rises sharply and barrier disruption becomes likely. Above 4.0, free acid value collapses and the product loses resurfacing capacity regardless of stated acid percentage.

The Lotion buffers to this window precisely. A formulation that lists 12% glycolic but sits at pH 5 is not the same product as a formulation that lists 12% glycolic at pH 3.8, even though label disclosure does not always make the distinction clear.

Keratin Compaction

Keratin compaction is the abnormal build-up of keratin around the follicular opening, producing the rough, raised bumps characteristic of keratosis pilaris and the textural irregularity of rough body skin.

It results from a combination of slowed corneocyte turnover, follicular hyperkeratosis, and often a genetic predisposition. The compacted keratin forms a plug that traps the hair beneath and produces the visible bump.

Exfoliating acids dissolve the compacted keratin and restore follicular patency over a treatment cycle of weeks to months. Mechanical exfoliation cannot reach the depth required for resolution, and physical extraction reliably worsens the inflammation that drives the cycle.

Body Resurfacing

Body resurfacing is the systematic chemical exfoliation of the body's stratum corneum to correct texture, tone, and follicular irregularity over a treatment cycle of typically 6 to 12 weeks.

It is distinct from body moisturising, which addresses surface dryness without correcting underlying texture. Resurfacing requires sustained exposure to a formulated active at therapeutic free acid value, applied to the affected area on a near-nightly cycle, with appropriate barrier support to prevent compensatory disruption.

The six-marker standard exists to distinguish products designed for resurfacing from cosmetic body lotions that include acids at non-therapeutic concentrations or pH.

Keratosis Pilaris (KP)

Keratosis pilaris is a benign, inherited condition of follicular hyperkeratosis that produces small, rough, raised bumps most commonly on the upper arms, thighs, buttocks, and occasionally cheeks, affecting an estimated 40% of adults and over 50% of adolescents.

It is not contagious, not infectious, and not curable in the sense that the genetic predisposition does not resolve. It is, however, reliably manageable. Sustained use of a 10% to 12% glycolic acid body lotion at therapeutic pH typically produces visible reduction within 6 to 12 weeks of consistent application.

KP responds to keratolytic actives. It does not respond to moisturisers, scrubs, or oils, which address surface symptoms without dissolving the keratin plug that causes them. A fuller treatment cycle is laid out in the KP guide.

Strawberry Legs

Strawberry legs is the visible appearance of darkened follicular openings on the legs, caused by trapped sebum, dead skin cells, or oxidised debris within follicles, often becoming pronounced after shaving.

It is not a single condition; it is a presentation that overlaps with keratosis pilaris, post-inflammatory pigmentation, and pseudofolliculitis (ingrown hair inflammation). The visible dot pattern can come from several underlying causes, sometimes simultaneously.

Sustained chemical exfoliation reduces the appearance by clearing follicular contents and accelerating corneocyte turnover around each follicle. Shaving technique matters as a secondary factor. A dedicated dermatology-led explanation is here.

Crepey Skin

Crepey skin describes a thin, finely wrinkled body skin texture, typically appearing on the upper arms, inner thighs, and décolletage, resulting from a combination of declining dermal collagen, cumulative photodamage, and disordered corneocyte turnover.

It is not synonymous with ageing skin in the general sense. It is a specific surface presentation, and one of the few body texture concerns that responds meaningfully to topical intervention rather than requiring dermal procedures.

Body resurfacing with AHAs improves the appearance by smoothing the stratum corneum, accelerating turnover, and stimulating a low-grade dermal response over time. The improvement is gradual and cumulative, not immediate. It does not replace lost dermal volume; it improves how that skin is presented at the surface.

Glycolic Acid

Glycolic acid is the smallest alpha-hydroxy acid molecule (76 daltons), traditionally derived from sugar cane, and the most penetrative AHA used in body skincare.

Its small molecular size allows it to reach deeper into the stratum corneum than lactic acid (90 daltons) or mandelic acid (152 daltons). For body resurfacing, glycolic at 10% to 12% with appropriate buffering is the dermatology benchmark for at-home, daily-use protocols.

The Lotion's hero product uses 12% glycolic acid at pH 3.6 to 4.0, the upper end of the at-home concentration range, where free acid value remains high enough for clinical effect without crossing into in-clinic peel territory.

Lactic Acid

Lactic acid is a larger alpha-hydroxy acid molecule (90 daltons) than glycolic, with milder exfoliating action and additional humectant properties that draw water into the stratum corneum.

It is often selected for sensitive skin, for combination formulations with other actives, or as a primary acid in lower-concentration products where surface hydration is as important as exfoliation. Its molecular size limits penetration depth compared with glycolic.

For dedicated body resurfacing where the goal is keratin compaction and follicular hyperkeratosis, glycolic typically outperforms lactic at equivalent percentages. Lactic plays a supportive role in certain formulation strategies rather than serving as the primary resurfacing active.

Urea

Urea is a humectant and keratolytic that, in body skincare, draws water into the stratum corneum at low concentrations and dissolves compacted keratin at higher concentrations.

At 5% to 10%, urea hydrates. At 10% to 30%, urea begins to break down keratin compaction directly, complementing the action of glycolic acid by addressing the same target structure through a different chemical mechanism.

In The Lotion's formulation, urea works synergistically with glycolic to address both surface hydration and deeper keratin build-up, allowing the resurfacing cycle to proceed without the surface dryness that often accompanies single-active acid lotions.

Niacinamide

Niacinamide (vitamin B3) is a barrier-supportive active that, in body skincare, reinforces ceramide synthesis, reduces transepidermal water loss, and modulates the low-grade inflammation associated with exfoliating actives.

At 2% to 5% in a body lotion, niacinamide serves three functions: it buffers the irritation potential of glycolic acid, supports long-term barrier integrity through a resurfacing cycle, and reduces post-inflammatory pigmentation, which is particularly relevant for strawberry legs and post-shaving discolouration.

It is the most-studied barrier-support active in cosmetic dermatology and one of the few that performs reliably across skin types and concentrations.