Analysis of Your Toner Formulation

Thank you for sharing your toner formulation and questions. Let's break down the potential causes for the crystal formation and the necessity of preservatives.

Crystal Formation

Based on the ingredients in your formula, the most likely cause for the crystals forming at the bottom of the bottle after about 20 days is the Licorice Extract (Licochalcone A 1%, Water-Soluble). The product description for this ingredient specifically mentions that in long-term storage, there may be sediment. This sediment can appear as crystals or fine particles at the bottom of the container.

While other ingredients like Zinc PCA or Willow Bark Extract (Natural Salicylic Acid) could potentially precipitate depending on the final pH and concentration of the formula, the Licorice Extract is explicitly noted for this behavior in its product information.

To address this, you can try gently shaking the toner before each use to disperse any sediment. Storing the product in a cool, dark place might also help minimize precipitation, although the description for Licorice Extract suggests refrigeration (5-8°C) for long-term storage to maintain quality and potentially reduce sediment.

Necessity of Preservatives

You asked if a preservative is still needed since you are not using distilled water. The answer is yes, preservatives are essential in any water-based cosmetic formulation, regardless of the water source (distilled or not). Non-distilled water contains microorganisms, and without adequate preservation, bacteria, mold, and yeast can grow in your product, leading to spoilage, reduced efficacy, and potential skin irritation or infection.

Your formula already includes two preservatives: Phenoxyethanol SA and Benzoic Acid (which is used to preserve the Witch Hazel Plus Allantoin). Phenoxyethanol SA is a broad-spectrum preservative blend (Phenoxyethanol, Caprylyl Glycol, and Sorbic Acid) designed to protect against a wide range of microorganisms. Using it at 0.5% is within the recommended usage rate for closed container products.

The combination of Phenoxyethanol SA and the Benzoic Acid from the Witch Hazel Plus Allantoin should provide adequate preservation for your toner. However, it is always highly recommended to perform a challenge test on your specific formulation to confirm the efficacy of the preservative system and ensure the product remains safe and stable throughout its intended shelf life, especially when using non-distilled water.