Serum Formulation Review

You've proposed a water-based serum formulation with several beneficial ingredients aimed at being non-sticky, fast-absorbing, and non-clogging. Let's review the compatibility, texture, and what might be needed to complete the formula.

Ingredient Compatibility

The ingredients you've listed are generally compatible in a water-based serum:

• Water (AQUA): The base.
• Glass Moist™: A moisturizer designed to be oil-free and non-clogging.
• MOIST24: A humectant that also helps improve texture and absorption.
• Glycerin: A common humectant.
• Pure-Succinic™ (Succinic Acid): An active with antibacterial properties, can help with acne. Works best in a slightly acidic to neutral pH range (3.5-6.5).
• Copper Peptide (GHK-Cu): An active peptide. Requires a specific pH range (4.5-7.4) for stability and efficacy. The description warns against using Disodium EDTA with it.
• Xanthan Gum: A thickener for creating the gel texture.
• Ethoxydiglycol: A solvent and penetration enhancer, helps dissolve ingredients and improve skin delivery. Your proposed 1.5% is within the typical usage rate limits for leave-on products.
• Tranexamic Acid: An active for brightening and reducing blemishes. Dissolves in water and works best in a pH range of 3-8.

Overall, the ingredients can be mixed. The key consideration is the final pH, which needs to be suitable for the stability and efficacy of Copper Peptide (4.5-7.4), Pure-Succinic (3.5-6.5), and Tranexamic Acid (3-8). A target pH between 4.5 and 6.5 would likely work well for all.

Texture (Non-sticky, Fast Absorption)

Your goal is a non-sticky, fast-absorbing serum.

• You have a high total percentage of humectants (Glycerin 10%, MOIST24 10%, Glass Moist 20% = 40%). While MOIST24 and Glass Moist are noted for good skin feel, 10% Glycerin can often contribute to tackiness, especially in combination with other humectants.
• Xanthan Gum at 0.75% will create a noticeable gel texture. The "easy to spread" type is helpful, but the overall viscosity might still feel a bit heavy or slightly sticky/stringy depending on the specific grade and how it interacts with the high humectant load.
• Ethoxydiglycol can help improve the feel and absorption speed.

To achieve a truly non-sticky, fast-absorbing serum, you might consider:

• Slightly reducing the total humectant percentage or replacing some Glycerin with humectants known for a lighter, less sticky feel.
• Experimenting with a slightly lower percentage of Xanthan Gum or trying a different rheology modifier that provides a lighter, faster-breaking gel texture.

Non-Clogging

The ingredients listed, particularly Glass Moist which is oil-free, are generally not known to be highly comedogenic in a water-based serum format. The formulation appears unlikely to be inherently pore-clogging for most skin types.

What to Add?

Based on standard cosmetic formulation practices and the ingredient descriptions, you absolutely need to add:

• Preservative System: Your formula is water-based and contains ingredients that can support microbial growth. While Glass Moist contains Phenoxyethanol and Pure-Succinic has some antibacterial action, this is likely insufficient to preserve the entire formula long-term. You need a broad-spectrum preservative system effective at your final target pH.
• pH Adjuster: You will need an ingredient (like Citric Acid or Sodium Hydroxide solution) to measure and adjust the final pH of the serum to the desired range (e.g., 4.5-6.5) for optimal stability and efficacy of your active ingredients and for skin compatibility.

Additionally, consider:

• Antioxidant/Stabilizer: The description for Tranexamic Acid suggests adding ActiveProtec™ OX 0.5% to help prevent discoloration over time. This could be a valuable addition for formula stability.

Mixing Instructions (General Guide)

1. In the water phase, disperse Xanthan Gum and stir/mix until fully hydrated and a gel forms.
2. Add Glycerin, MOIST24, Ethoxydiglycol, Pure-Succinic, and Tranexamic Acid to the water/gel phase and mix until dissolved/dispersed.
3. Prepare the preservative system separately if needed and add it to the main batch.
4. Add Copper Peptide solution and Glass Moist. Both should be added in the final step at a temperature below 40°C.
5. Mix thoroughly.
6. Measure the pH and adjust it to your target range (e.g., 4.5-6.5) using a pH adjuster.
7. Mix again until uniform.

Always make a small test batch first to evaluate the texture, feel, clarity, stability, and pH before making a larger quantity.