Formulation Advice for Bergamot Serum/Essence

Hello! It's great you're experimenting with natural ingredients like kaffir lime. Creating your own serum with bergamot scent sounds lovely for a relaxing nighttime routine. Let's look at your proposed formula and discuss the ingredients and percentages.

Here's a breakdown of your proposed ingredients and some recommendations:

• Warp Cream Maker (5%): This is an emulsifier, which is necessary to combine the water-based ingredients (water, extracts, preservative) with the oil/silicone-based ingredients (Cyclomethicone, Bergamot Essential Oil). 5% is a typical usage rate for creating an emulsion, and it will contribute to the texture.
• Cyclomethicone (5%): This is a volatile silicone that provides a smooth, silky feel and helps with spreadability. It evaporates after application. 5% is a common percentage.
• Silicone Gel (Vinyl Dimethicone Crosspolymer): You asked if this is needed and at what percentage for a liquid texture slightly thicker than oil. Silicone Gel is primarily a thickener and texturizer used to create a gel-like feel or increase viscosity significantly. For a liquid serum that can be used with a dropper, you likely do not need this ingredient. The combination of Warp Cream Maker, extracts, and water should give you a suitable liquid viscosity. Adding Silicone Gel will likely make it too thick and gel-like, which is not your goal. I recommend omitting the Silicone Gel from your formula.
• Bergamot Essential Oil (0.5% - 1%): You like the scent and its calming effect. IMPORTANT SAFETY NOTE: Bergamot essential oil contains furocoumarins (like bergapten) which are highly phototoxic, meaning they can cause severe skin reactions (burns, hyperpigmentation) when exposed to UV light (sunlight). For leave-on facial products, it is crucial to use a bergapten-free (FCF) version of Bergamot Essential Oil. Even FCF versions can sometimes cause sensitization in sensitive individuals. Given this is a facial product, I recommend using a lower percentage, such as 0.5% or even less, especially if you cannot confirm it is bergapten-free. Always patch test the final product on a small area of skin before applying to your face.
• Cucumber Extract (3% - 5%) & Aloe Vera Extract (1% - 3%): You want recommendations for moisturizing and cooling effects. These are great choices for hydration and soothing the skin. For a noticeable effect, you can use them towards the higher end of your proposed ranges. A good starting point could be 5% Cucumber Extract and 3% Aloe Vera Extract. However, always check the supplier's recommended usage rate for the specific concentration of extract you have, as this can vary.
• Preservative (Phenoxyethanol SA / Optiphen Plus, 0.5% - 1%): You are right to use a preservative, especially with water and extracts. Your confusion about the percentage relates to its solubility properties vs. its effective preservation concentration. Phenoxyethanol SA (Optiphen Plus) is a broad-spectrum preservative blend. The recommended usage rate for effective preservation in most cosmetic formulations is typically 0.75% to 1.5%. For a water-based product containing extracts, using 1% is a good, safe concentration to ensure adequate preservation against bacteria, yeast, and mold. Add the preservative during the cooling phase of your formulation (usually below 40-60°C, check supplier instructions).
• Distilled Water: This will be the balance to make up 100% of your formula.

Revised Formula Structure Recommendation (Example):

• Warp Cream Maker: 5%
• Cyclomethicone: 5%
• Bergamot Essential Oil (FCF recommended): 0.5% (or less)
• Cucumber Extract: 5%
• Aloe Vera Extract: 3%
• Phenoxyethanol SA (Optiphen Plus): 1%
• Distilled Water: Balance to 100% (e.g., 100 - 5 - 5 - 0.5 - 5 - 3 - 1 = 80.5%)

Making the Serum:

You will likely need to heat the water phase (water, extracts, preservative if heat stable) and the oil/silicone phase (Warp Cream Maker, Cyclomethicone, Bergamot EO if heat stable, though usually added during cooling) separately to around 70-75°C, combine them while mixing well to form the emulsion, and then continue mixing while cooling. Add heat-sensitive ingredients like extracts (if not added to the water phase initially) and the preservative below their maximum temperature limits (usually 40-60°C). Add the Bergamot Essential Oil during the cooling phase, typically below 40°C, to preserve its scent.

Summary:

Your proposed ingredients are suitable for a serum, but I recommend omitting the Silicone Gel to achieve a liquid texture. Use 1% Phenoxyethanol SA for proper preservation. Most importantly, use a bergapten-free Bergamot Essential Oil and keep the concentration low (0.5% or less) for facial safety. Adjust the percentages of Cucumber and Aloe Vera extracts within their recommended ranges based on your desired feel.

Remember to always make a small test batch first and perform a patch test on your skin before using the product on your face.

Good luck with your formulation!