Natural Preservatives for Your Serum

Creating a serum with natural ingredients is a great goal. Based on your questions and the information available, here's a guide to choosing natural preservatives for your formulation:

Natural Extracts as Preservatives

You asked if natural extracts like Aloe Vera Extract, Sea Kelp Extract, Cucumber Extract, Green Tea Extract, or active extracts like AcneBee could serve as both active ingredients and preservatives. While these extracts offer wonderful benefits for the skin, they are not sufficient on their own to protect your serum from microbial growth. Cosmetic formulations, especially water-based ones, require a dedicated preservative system to ensure safety and stability throughout their shelf life. Even if an extract contains a small amount of preservative (like the Sea Kelp Extract you mentioned containing Phenoxyethanol), this is typically only enough to preserve the extract itself before it's added to a larger formula.

1,3-Propanediol, which you also listed, is a natural solvent and humectant that can act as a preservative booster, but it is not a standalone preservative.

Recommended Natural Preservatives

For a truly natural serum that is effectively preserved, you should incorporate a broad-spectrum natural preservative system. From the options you researched, the following are suitable natural preservatives:

• NaturePreserve™: This is a 100% natural preservative system containing Gluconolactone and Sodium Benzoate. It is effective against bacteria, fungi, and yeast and works within a pH range of 3-6. The recommended usage rate is typically 0.75-2.0% depending on the product type and risk of contamination.
• Thyme Care™: This natural preservative is extracted from Thyme and Bois De Rose. It contains Thymol, Linalool, and Phenethylalcohol and is effective against a broad spectrum of microbes. The recommended usage rate is 0.8% and it works in a wide pH range (2-10). Note that it has a natural thyme scent that might require masking with fragrance.

1,2-Hexanediol, which you also listed, is not classified as a preservative but acts as a strong preservative booster and has some inherent antimicrobial properties. It can be used at 3% alongside other preservatives to enhance their effectiveness and potentially reduce their required concentration.

Disodium EDTA, another ingredient you listed, is a chelating agent, not a preservative. It helps improve formula stability but does not protect against microbial contamination.

Calculating Preservative Amount

Regarding your question about calculating the preservative amount when some ingredients already contain a preservative: The small amount of preservative in an ingredient is usually not enough for the final product. For the most accurate preservation, you should calculate the required percentage of your chosen preservative based on the total weight of your final serum formula. While you could technically factor in the tiny amount from individual ingredients, it's common practice to add the full recommended amount of your chosen preservative system to ensure adequate protection, especially in water-based formulas which are prone to microbial growth.

In summary, focus on incorporating a dedicated natural preservative like NaturePreserve™ or Thyme Care™ into your serum formulation to ensure its safety and longevity.