Formulation Questions: Water Phase Limits, Emulsifiers, Petrolatum, and Texture

Based on the conversation, here are the answers to your questions regarding the use of lecithin and the proposed night repair serum formula:

Regarding your initial questions about lecithin:

1. HLB Calculation for Lecithin: While not strictly required, calculating the required HLB (Hydrophilic-Lipophilic Balance) for your oil phase can help you estimate the appropriate amount of emulsifier needed. This can reduce trial-and-error, saving time and potentially expensive ingredients, especially for larger batches. For small-scale or personal use, you can choose to rely on trial-and-error if you prefer.
2. Fixing Separation with Insufficient Lecithin: The staff requested details of your formula to provide specific advice on fixing separation. However, generally, if an emulsion separates due to insufficient emulsifier, it's challenging to fix it perfectly after it has broken. You might attempt to re-emulsify by adding more lecithin and re-mixing vigorously, possibly with heating if the ingredients allow, but success is not guaranteed, and the texture might be compromised.

Regarding your proposed night repair serum formula and follow-up questions:

The staff advised against using emulsifiers that require heat for your formula due to the presence of expensive, potentially heat-sensitive ingredients. If heat is necessary for other parts of the process, the sensitive ingredients should be added in the final cooling phase.

Using Soy Lecithin for this formula, especially with a high water content, might require a relatively large amount, which needs to be determined through testing. This is a characteristic of Soy Lecithin, although it offers benefits like good skin penetration and being 100% natural.

Your concerns about the formula:

1. Lecithin vs. Pro Polymer: Given the heat sensitivity of some ingredients and the potential need for high amounts of lecithin with trial-and-error, switching to an emulsifier like Pro Polymer that may not require high heat could be a better approach to minimize the risk of degrading expensive ingredients and simplify the process.
2. Formula Thickness: The staff noted that the proposed formula, with its oil content, is likely suitable for dry skin or use in dry environments (like air-conditioned rooms). The viscosity will depend on the specific ingredients and their percentages.
3. Petrolatum Amount: Lanolin, Squalane, and Rose Hip Oil in your original formula already provide occlusive and moisturizing effects. Adding Petrolatum might not be necessary unless your skin is very dry. The amount of Petrolatum to add depends entirely on the desired level of occlusive effect you want, as it primarily acts as a barrier and lubricant. There's no standard percentage; it ranges from small amounts in creams to 100% in products like Vaseline.

Regarding your questions after considering Pro Polymer:

1. Maximum Water Phase Ingredients with Pro Polymer: There is no fixed maximum percentage for ingredients in the water phase when using Pro Polymer or any thickener/emulsifier. The total percentage of water phase ingredients (excluding water itself) and their nature (powder, liquid, inherent stickiness) will determine the final viscosity and feel. A high percentage of solid or inherently sticky water-soluble ingredients, even with sufficient water, can result in a thick or sticky product.
2. Petrolatum Amount with Safflower Oil: Similar to the previous answer, the amount of Petrolatum to use with 5% Safflower oil depends solely on the desired occlusive effect. Safflower oil is an emollient, but Petrolatum provides a strong barrier effect. Decide how much barrier protection you need to determine the Petrolatum percentage.
3. Fixing Thickness/Stickiness: If the final mixture is too thick or sticky, adding ingredients like Butylene Glycol (a solvent/humectant) or AminoSilk (a texture enhancer) might help improve the feel or reduce stickiness, but it's not guaranteed and depends on what is causing the issue. Adding more oil might make it feel less sticky initially but could increase the overall greasiness or heaviness, which might not be desirable. Adjusting the water percentage (if possible without compromising stability) or reducing the percentage of thickening/gelling agents or sticky ingredients are more direct ways to reduce viscosity.

Additionally, the staff recommended incorporating vitamins like Vitamin B3 (Niacinamide) and Vitamin B5 (Panthenol) into your formula. These offer significant skin benefits, are relatively inexpensive, and using a variety of beneficial ingredients is often more effective than using high concentrations of just a few.