Tag: gelling agents

How to formulate a SERUM

Hyaluronic Acid Serum

LAB NOTES & SAFETY NOTICE
These are personal experiments for educational use only— not instructions and not for commercial or consumer use. By proceeding, you assume all risks related to safety, testing, and regulatory compliance.
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This post is a great way to show how formulation shifts when you move from “heavy” emulsions to “active-heavy” serums. In 2026, the trend is all about “minimalist science,” so framing this as your Technical Brief on Aqueous Systems is perfect.

Here is the “Studio” revamp, using the Lab Notes persona.

Lab Notes: Observations on Aqueous Systems & Serum Theory

In my formulation research, serums represent a distinct category of product design. While lotions are designed for barrier protection and emollience, serums are engineered as high-delivery systems for specific active components. Below are my documented observations on the characteristics and structural theory of these fluid systems.

Defining Characteristics of a Serum

In my lab records, I categorize a “Serum” based on these specific technical parameters:

  • Lipid Load: Systems are typically very light, with a total fat content often documented between 1.5% and 4%.

  • Viscosity ($\eta$): Serums are designed to be fluid or semi-fluid rather than high-viscosity creams.

     

  • Active Density: They are formulated to hold a higher concentration of “hero” ingredients.

     

  • Cold Process Theory: Because the lipid load is so low, many of my serum experiments are conducted at room temperature (Cold Process), preserving the integrity of heat-sensitive vitamins.

Theory Perspective: If a cream is the “protector” of the skin, a serum is the “booster.” Expecting a serum to provide the same occlusion as a rich cream is a common misconception in formulation theory; they serve different physiological goals.

Structural Phases in Serum Design

Phase A: The Aqueous Base

Phase A is the backbone of the serum. In my experiments, I focus heavily on the choice of Rheology Modifiers (gelling agents) to determine the “pick-up” and “after-feel” of the product.

  • Robustness: I prioritize gelling agents that can withstand high electrolyte (salt) loads from actives.

  • My Go-To Polymers: I often record the use of Xanthan Gum or Hydroxyethylcellulose (HEC). Note that HEC requires a thermal trigger to hydrate, which I account for in my processing notes if cold-sensitive actives are involved.

Phase B: The Targeted Lipid Phase

Even in a water-heavy system, a small lipid phase is often necessary to carry oil-soluble vitamins (like Vitamin E/Tocopherol).

  • Solubilization vs. Emulsification: In my lab, when the oil phase is under 2%, I often experiment with solubilizers (surfactant-based materials) rather than traditional waxes. This allows the final system to remain translucent and liquid.

  • Cold Emulsifiers: For serums, I frequently document the use of liquid, room-temperature emulsifiers to maintain a “Cold Process” workflow.

Phase C: The Active Integration

In serum theory, the line between Phase A and Phase C is often blurred. Since many serums are cold-processed, I can incorporate the actives directly into the water phase from the start.

Hyaluronic Acid: The Dual-Purpose Ingredient

I’ve found that Sodium Hyaluronate is a fascinating case study in serum design. It acts simultaneously as a high-performance active and a gelling agent. In my records, I’ve noted that a high-molecular-weight Hyaluronic Acid can create a complete serum structure on its own, requiring nothing more than water and a preservative.

Concluding Thoughts on Serum Strategy

Designing a serum is an exercise in precision. Because the formula is so “exposed” (lacking the heavy waxes of a cream), every ingredient must be perfectly balanced to avoid tackiness or instability. I find these systems to be the ultimate test of an active ingredient’s compatibility with a base.

What’s next in the lab?

I am currently reviewing my notes on Niacinamide stability within these aqueous systems. If you have specific observations on pH-sensitive actives in serums, I’d love to compare data!

Formulating a lotion: Phase A – THEORY pt.3

LAB NOTES & SAFETY NOTICE
For educational purposes only. Content reflects personal, non-professional formulation experiments and is not instructional.
No formula or information on this site is intended for commercial use, consumer application, or third-party use.
Accessing this content means you accept all risks and full responsibility for safety, testing, legal compliance, and outcomes.
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Observations on Phase A (The Aqueous Phase)

In my formulation journey, Phase A (The Water Phase) is the foundation of every emulsion. My standard procedure usually involves heating this phase to 70°C in a double boiler. This ensures that when Phase A and Phase B are combined, they are at the same temperature, which is a prerequisite for a stable emulsion with the heat-required emulsifiers I typically use.

Component 1: The Solvent (Water & Hydrosols)

I’ve recorded that any standard lotion requires a water content of at least 70%. While I sometimes experiment with herbal hydrosols for their delicate scent, my research suggests that their volatile properties can be sensitive to the high heat required for emulsification. In my lab, I prioritize investing in active ingredients rather than expensive floral waters.

Component 2: Humectants (Glycerin)

Glycerin is a staple in my lab because it is highly hygroscopic, meaning it possesses the chemical ability to attract and bind water molecules.

  • Experimental Observations: Glycerin prevents the final product from drying out. However, my notes show that exceeding certain percentages can lead to a “tacky” or “shiny” finish on the skin.
  • My Working Percentages:
    • 1.5%: Minimum for blemish-prone/oily skin theory.
    • 2.0% – 3.5%: Standard for normal to dry skin batches.
    • 4.0% – 5.0%: Targeted for body lotions where higher hydration is the goal.

Component 3: Rheology Modifiers (Gelling Agents)

I use gelling agents not just for texture, but as essential stabilizers for the emulsion. Here are my personal notes on the polymers I’ve tested:

Xanthan Gum

A reliable polysaccharide that remains stable even in the presence of electrolytes (salts).

  • Observation: Using high percentages (>0.5%) can lead to a “pilling” effect or a film-forming sensation that feels occlusive.
  • My Method: I disperse the gum in glycerin first to avoid “fish-eyes” (lumps), then slowly incorporate water.

Carbopol® Ultrez 21 (Carbomer)

This is one of my favorite polymers for creating elegant, crystal-clear gels with a “premium” skin feel and zero “soaping” (white-trail) effect.

  • Stability Constraints: I’ve documented that this polymer is highly sensitive to electrolytes (like Sodium Hyaluronate/Hyaluronic Acid) and requires a pH of approximately 6.0 to fully “bloom” and thicken.
  • My Method: I sprinkle the polymer on the surface of the water and allow it to self-wet (hydrate) without stirring to avoid air entrapment.
  • The Neutralization Process: Because the polymer is acidic, the water remains liquid until I add a neutralizing agent (like a 10% Sodium Hydroxide solution). I typically blend this with Xanthan Gum (0.2% Xanthan / 0.4% Carbomer) for a “best of both worlds” stability profile.

Hydroxyethylcellulose (HEC)

A non-ionic gelling agent that I use when a formula requires high electrolyte stability or a specific “stringy” viscosity.

  • Observation: Unlike the others, I’ve found that HEC requires heat (70°C) to fully hydrate and thicken.
  • My Method: I add it to pre-heated water while stirring vigorously, followed by a short burst with an immersion mixer to ensure a smooth, lump-free gel.

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