DIY body scrub: what cosmetic chemistry thinks of your kitchen recipes

Every week, thousands of people google how to make a body scrub at home and get roughly the same answer: mix sugar with oil, add an essential oil — and you're done. Technically, it works. But if you have ever noticed that after such a scrub your skin either dries out, turns red, or feels like you didn't so much exfoliate it as offend it — that is no accident. It is chemistry that no one explained.

Let’s be honest: a homemade scrub is not just "mix and apply." It is a small formula with a physical and chemical mechanism of action, with rheology, with ingredient interaction, and, most importantly, with your specific skin type. And this is exactly where most recipes on the internet fall silent.

An abrasive is not just "something hard"

Physical exfoliation works through the mechanics of friction: abrasive particles remove corneocytes — dead cells of the stratum corneum — mechanically. But here is what matters: not all abrasives are created equal, and their choice directly affects what happens to the skin barrier after the procedure.

Particle size, shape, and hardness

Three parameters determine how aggressive an abrasive is:

• Particle size. Fine granulated sugar (~300–500 µm) works more gently than coarse sea salt (~1000–2000 µm). Coffee grounds occupy an intermediate position (~400–700 µm depending on the grind).
• Particle shape. Salt and sugar crystals have sharp edges — if applied aggressively, they can create micro-injuries. Coffee grounds and ground nuts are more rounded and less traumatic.
• Solubility. Sugar and salt dissolve in water and on the skin — this means that the abrasiveness decreases during application. This is a plus for sensitive skin, but a minus for those who want an intense effect.

Walnut shells and apricot kernels are a different story. Under a microscope, their shape resembles shards of glass, which is why they have long been questioned in professional cosmetology: irregular sharp edges create micro-tears that are invisible to the naked eye but provoke inflammation. This is not a scare tactic — it is simply surface physics.

What happens to the barrier after a scrub

The stratum corneum is not just "dead cells." It is a structured matrix of corneocytes and intercellular lipids (ceramides, cholesterol, and free fatty acids in a ratio of approximately 1:1:1) that retains water and protects against pathogens. Mechanical exfoliation partially disrupts this structure — and that is exactly why it is so important to apply something after a scrub that will help the barrier recover.

If you are formulating anhydrous products or oil bases for scrubs, this is especially relevant: the oil in a scrub formula doesn't just "soften," it creates an occlusive layer that temporarily reduces transepidermal water loss (TEWL) after mechanical exfoliation.

The chemistry of sugar, salt, and honey: what these ingredients actually do

A popular DIY honey body scrub is not just a nice combination. Honey performs several functions here simultaneously, and none of them are accidental.

Honey as a functional ingredient

Natural honey is a complex mixture: ~80% sugar (mainly fructose and glucose), ~17–18% water, plus enzymes (glucose oxidase, catalase), organic acids, flavonoids, and trace elements. What does this provide in a scrub?

• Humectancy. Fructose and glucose are hygroscopic compounds; they attract water from the air to the skin's surface. This is the same principle as glycerin, just less concentrated.
• Mild acidity. The pH of honey is about 3.9–4.5, which is close to the natural skin pH (4.5–5.5). This helps maintain the acid mantle that we work so hard to protect.
• Antimicrobial effect. The hydrogen peroxide released by glucose oxidase and the high osmotic activity create an environment unfavorable for bacteria. This explains the historically high stability of honey without preservatives.
• Texturizing properties. Honey increases the viscosity of the mixture and helps keep abrasive particles in suspension.

If you are interested in how food ingredients work in cosmetics at a chemical level, there are many overlaps with what we are discussing here.

Sugar vs. salt: when to choose which

Sugar (sucrose) is gentler, dissolves faster, and is less irritating. It is suitable for the face (if you are making a face scrub) and for sensitive body skin. Sea salt is a more intense abrasive and contains minerals (magnesium, potassium, calcium), but it causes stinging when applied to damaged or irritated skin. The classic rule: salt for feet and rough areas, sugar for everything else.

An important nuance: both sugar and salt create a hyperosmotic environment in an aqueous medium, which can theoretically draw water out of the upper layers of the skin. This is why oil in the formula is not an option, but a necessity: it creates a barrier and compensates for this effect.

The oil phase: not just "softening"

Most DIY scrubs are built on an "abrasive + oil" scheme. But choosing an oil is a science in itself, and this is where real cosmetic chemistry begins.

Fatty acid profile and comedogenicity

Oils differ in their fatty acid composition, and this determines how they behave on the skin:

• Coconut Oil (Cocos Nucifera Oil) — high lauric acid content (C12, ~48%), creates a dense occlusive layer. Comedogenicity — 4/5. Excellent for dry body skin, but not for oily skin.
• Sunflower Oil (Helianthus Annuus Seed Oil) — rich in linoleic acid (C18:2, ~65%), absorbs easily, comedogenicity — 0/5. A versatile choice.
• Jojoba Oil (Simmondsia Chinensis Seed Oil) — technically a liquid wax, mimics skin sebum, non-comedogenic. Good for stabilizing a mixture.
• Almond Oil (Prunus Amygdalus Dulcis Oil) — rich in oleic acid (C18:1, ~70%), nourishing, comedogenicity — 2/5.

If you want to understand how to systematically choose an oil for your skin type, that is a separate, extensive topic that we covered in our guide to oils and butters.

Stability of the oil base

Here lies a problem that culinary blogs keep quiet about: oils oxidize. Oils with a high content of polyunsaturated fatty acids (PUFAs) oxidize especially quickly: flaxseed, hemp, and rosehip oils. When in contact with air, light, and heat, they go rancid — and applying rancid oil to the skin means applying oxidation products that provoke inflammation.

Practical solution: add tocopherol (Vitamin E, Tocopherol) to your oil base at a concentration of 0.1–0.5% — this is an antioxidant that slows down oxidation. You should store the scrub in a dark container, in a cool place, and use it within 2–4 weeks.

By the way, regarding the stability of cream formulas — if you are interested in how to test homemade products for stability, we have a separate article specifically on this.

pH and the skin barrier: what all homemade recipes forget

Skin has a slightly acidic pH — on average 4.5–5.5. This is not just a number: the acid mantle is an active protective environment where desquamation enzymes (kallikreins) work, commensal bacteria live, and the integrity of the barrier is maintained.

Most homemade scrubs have a neutral or slightly alkaline pH — especially if they contain baking soda (a popular ingredient in DIY recipes). Soda has a pH of about 8.3 — this means that after application, it temporarily alkalizes the skin surface, disrupts enzyme function, and creates conditions for the growth of pathogenic flora.

Honey, in this sense, is one of the few "kitchen" ingredients that works in the correct pH range. Read more about why pH is so important in any cosmetic formula in our guide: pH in cosmetics: a basic guide for formulators.

Preservation and microbiology of homemade scrubs

Here is a topic that almost all DIY blogs overlook. If your scrub contains water — and it appears the moment you apply the product with wet hands or add a water-based ingredient — you have an environment for microbial growth.

Anhydrous scrubs: a relatively safe zone

A classic "abrasive + oil" scrub without water is an anhydrous system. Bacteria do not multiply without water, so such a product is relatively stable without preservatives. But "relatively" is the key word: as soon as you reach into the jar with wet hands, you introduce water and contamination. The solution is a spoon or spatula.

Read more about how anhydrous systems work and why they require a special approach: Anhydrous products: A complete guide for beginners.

Scrubs with a water phase: a preservative is needed

If you add aloe vera gel, hydrosol, milk, or any other water-based component to your scrub, you need a preservative. Without one, the product may look fine but contain a dangerous microbial load within just 3–5 days at room temperature. The topic of preservation is complex and multifaceted — we analyzed it in relation to clay masks: Preserving clay masks.

Basic formulation: how a cosmetic chemist thinks

When a professional chemist develops a body scrub at home, they don't think in terms of recipes, but in terms of functions. Each ingredient plays a specific role in the formula:

1. Abrasive (50–70%) — the main working fraction. Sugar, salt, coffee grounds. The size and shape of the particles determine the intensity.
2. Carrier oil (25–40%) — creates slip during application, reduces friction, and nourishes the skin afterward. Choose according to skin type.
3. Functional additives (up to 10%) — oil-soluble actives, essential oils (0.5–2%, no more), tocopherol (antioxidant, 0.1–0.5%), extracts.
4. Texturizing components (optional) — waxes (beeswax, carnauba) to stabilize the suspension if you want a denser texture.

An example of a basic anhydrous formula (% of total mass):

• Sucrose (fine sugar) — 59%
• Helianthus Annuus Seed Oil — 30%
• Cocos Nucifera Oil — 10%
• Tocopherol — 0.3%
• Parfum / essential oil — 0.7%

This is not an "internet recipe" — this is a functional formula with a justification for each component. This is exactly how a cosmetic chemist thinks: not "what to add," but "why is this here and in what concentration."

If you want to learn how to formulate exactly like this — with an understanding of the mechanisms, rather than just following someone else's recipes — check out the Walker Formulation Academy Club. There, we analyse formulations from the basics to advanced techniques.