Serum Formulation Review

Based on the ingredients you've listed:

• HEC: Hydroxyethylcellulose
• PHC: Phenoxyethanol + Chlorphenesin

Here is a review of your serum formula and questions:

Formula Feasibility

The ingredients you've chosen (Distilled Water, Hydroxyethylcellulose, Glycerin, Phenoxyethanol + Chlorphenesin, Liquid Beta-glucan) are standard components for a water-based gel serum. The percentages you've indicated are generally within typical usage ranges for these ingredients in such a formulation. Therefore, this formula is feasible to create a serum, assuming you use appropriate cosmetic-grade ingredients and follow proper mixing procedures.

Adding Liquid Beta-glucan

According to the product information for Beta Glucan, it should be mixed in water at a temperature not exceeding 50°C. The Hydroxyethyl Cellulose (HEC), however, typically requires heating the water phase to around 70°C to dissolve properly and form a gel.

Given this temperature requirement for HEC, you should first prepare your water phase with HEC and Glycerin, heat it to 70°C while stirring until the HEC is fully dissolved and the gel forms. After the gel has formed, you must let the mixture cool down to below 50°C before adding the Liquid Beta-glucan. The preservative blend (Phenoxyethanol + Chlorphenesin) should also be added in the final step after the mixture has cooled, as its product description indicates adding below 60°C.

So, the correct order would be:

1. Combine Distilled Water, HEC, and Glycerin.
2. Heat to 70°C and stir until HEC is dissolved and gel forms.
3. Cool the mixture down to below 50°C.
4. Add Liquid Beta-glucan and stir to disperse.
5. Add Phenoxyethanol + Chlorphenesin preservative blend and stir to combine.

Expected pH

The final pH of your serum will depend on the pH of each ingredient and their interaction in the mixture. While Beta Glucan is recommended to be used in a pH range of 5-7, and the Phenoxyethanol + Chlorphenesin preservative blend works best in pH 4.0-7.0, the combination of all ingredients does not guarantee the final pH will automatically fall within this range.

It is essential to measure the pH of your finished serum using a pH meter or pH strips. If the pH is outside the desired range (typically 5.0-7.0 for skin compatibility and ingredient stability), you should adjust it using a suitable cosmetic-grade pH adjuster (such as a dilute solution of citric acid to lower pH or sodium hydroxide/Triethanolamine to raise pH).