Preservative Needed for Water-Based Mixture

Yes, you should add a broad-spectrum preservative to your mixture of Rice Vitamin (Inositol, Vitamin B8), Cucumber Extract (France), and Lavender Water (Lavandula Angustifolia), even though the Lavender Water makes up 90% of the formula.

Here's why:

• Lavender Water contains a preservative (Phenoxyethanol 0.8%) and is preserved by the manufacturer. The product description indicates that if used as the main ingredient (over 60%), no additional preservative is needed for the Lavender Water itself.
• However, you are adding other ingredients: Rice Vitamin (a water-soluble powder) and Cucumber Extract (a preservative-free, water-soluble liquid).
• Adding these unpreserved, water-soluble ingredients introduces components that can support microbial growth and can potentially dilute the concentration of the preservative from the Lavender Water below the level needed to protect the entire mixture.

To ensure the stability and safety of your final product, especially considering that both Rice Vitamin and Cucumber Extract are recommended for refrigerated storage, it is best practice to include a suitable broad-spectrum preservative in your formulation.