Tag: preservatives

How to make a lotion – THEORY pt.1

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Escin and Caffeine Eye Cream14

Fundamentals of the Emulsion (The Basics)

After reviewing my initial attempts at body butters, I recognized that a deeper investigation into the chemistry of skin-care systems was necessary. These notes represent my ongoing study into the mechanics of facial and body emulsions. While the science of formulation is complex, I’ve distilled the core structure into four essential pillars.

The Four Pillars of a Basic Emulsion

In my lab, a standard “Phase-Zero” lotion consists of:

  1. Water (The Solvent)

  2. Lipids (Oils and Butters)

  3. The Emulsifier (The Bonding Agent)

  4. The Preservative (The Stabilization Agent)

While additional components like thickeners and actives are eventually integrated, understanding these four is the first step in my documentation process.

1. The Mechanics of Hydration

Water provides the initial hydration. However, my research confirms that water alone is insufficient, as it evaporates rapidly from the skin’s surface. Lipids (fats) act as occlusives, preventing this Trans-Epidermal Water Loss (TEWL) while providing nutrients.

Note on Emulsification: Studies indicate that an emulsified system (where water and fats are chemically bound) hydrates the skin more effectively than a simple “shake-and-apply” mixture of oil and water. The emulsion allows for a more uniform delivery of both phases.

2. Preservation: A Mandatory Standard

In my lab, preservation is not optional. Anytime water is present in a formula, it becomes a potential breeding ground for bacteria and mold.

  • The Reality of “Natural”: While some prefer to avoid preservatives, my lab standards require them for safety. I select preservatives based on their eco-profile and efficacy at low concentrations (typically around 0.5%).

  • Storage: Without a professional preservation system, a water-based product would require refrigeration and would have a shelf life of only a few days.

3. Aqueous Phase: Selecting the Water

In my experiments, I use demineralized, microbiologically pure water. This prevents mineral interference with the emulsifiers.

  • Floral Hydrosols: While I sometimes record the use of rose water or witch hazel, I often categorize these as “poetic” ingredients. They offer sensory value but, in my experience, provide less functional “hero” properties than concentrated actives.

4. Lipid Phase: The “Fall” of Fats

My documentation for the oil phase emphasizes balance over “miraculous” claims. I’ve learned that a professional formulation requires a strategic blend of fats based on:

  • Viscosity and Density ($\rho$)

  • Spreading Ability

  • Skin Feel

I have developed a specific “Grease-Fall” rule to ensure that the lipids are balanced for the intended purpose of the cream.

5. Emulsifiers: The Stabilizing Bridge

Emulsifiers determine the final “architecture” of the cream. My notes categorize them by:

  • Processing Temperature: Some require heating to 70°C, while others are “Cold Process” stable.

  • System Type: O/W (Oil-in-Water) for lighter textures vs. W/O (Water-in-Oil) for heavy barrier creams.

  • Sensory Profile: Determining if the final touch is dry, rich, or velvet-smooth.