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Writer's pictureYour Cosmetic Chemist

Why a Formula May Not Work for You, Even If It Worked for Others

Formulating cosmetics can be a complex process, and even the smallest changes can

significantly impact the final product. You may find that a formula works perfectly for someone else but doesn't turn out the same when you try it. Understanding why this happens can save you a lot of frustration and help you achieve better results. Here are three key factors that can influence the outcome of your formulation:


1) Ingredients: Same INCI, Different Results

Ingredients listed with the same INCI (International Nomenclature of Cosmetic Ingredients)

name may not be identical, even though they appear to be the same on paper. This is especially true when purchasing from different suppliers.


Why Does This Happen?

Emulsifiers are a prime example of this issue. These complex ingredients are often made from more than one raw material. The percentage of each raw material in the emulsifier can vary significantly from one manufacturer to another. This difference can affect not only the viscosity of your final product but also its stability. Even if two emulsifiers share the same INCI name, their performance in your formulation can differ.


Example of BTMS50 INCI: Behentrimonium Methosulfate (and) Cetyl Alcohol (and) Butylene

Glycol

One supplier's manufacturer might have BTMS50 might be made up of:

50% Behentrimonium Methosulfate (and) 25% Cetyl Alcohol (and) 25% Butylene Glycol

While other supplier’s could be made up of:

50% Behentrimonium Methosulfate (and) 45% Cetyl Alcohol (and) 5% Butylene Glycol

The results in the final viscosity of the product would be completely different from one another.


How to Avoid This Issue:

Always check the CAS number (Chemical Abstracts Service number) of the ingredient to ensure you are using the exact same material as in the original formulation. CAS numbers are unique identifiers for chemical substances and can help you confirm that the ingredient you’re using is truly the same.


Note: Small-scale suppliers often don’t use an ingredient’s actual trade name, making it

challenging for home formulators to ensure they’re using the exact same ingredient. Cosmetic chemists working with manufacturers always specify trade names to guarantee consistency.


Home formulators, however, may not have access to these trade names, as they aren’t

purchasing directly from the manufacturer. This crucial aspect is often not taught in online

natural skincare courses but becomes essential when you start scaling up your formulations.

Pro Tip: Cross-checking INCI names can help, but learning to identify ingredients by their CAS numbers will give you even greater accuracy.


2) Substitutions: It’s Not Always a Simple Swap

It may seem like a simple substitution to swap out one ingredient for another, but this can

sometimes lead to unexpected results. Each ingredient has specific properties, including charge (positive, negative, or neutral) and function within a formulation. These factors influence how the ingredient interacts with others and the final outcome of the product.


For Example:

While you can generally substitute carrier oils at the same percentage, doing so will alter the

skin feel of your final product. A lighter oil like grapeseed will create a different texture compared to a richer oil like avocado. Similarly, substituting an emulsifier or preservative can drastically change the stability and efficacy of your product.


3) Mixing: Technique and Order Matter

Mixing is not just about combining ingredients; it’s a critical part of the formulation process that can affect the stability, texture, and overall quality of your product. The tools you use and the order in which you mix your ingredients are just as important as the formulation itself.


Why Mixing Matters:

Using the wrong tool for mixing can lead to poor emulsification, resulting in separation or a

grainy texture. Similarly, adding ingredients in the wrong order can prevent them from fully

integrating, leading to an unstable product. Some ingredients are shear-sensitive, meaning they can be damaged by excessive or improper mixing, which can negatively impact their

effectiveness.


Best Practices for Mixing:

Tools: Use high-shear mixers for emulsions and stick to gentle stirring for delicate

ingredients. Unless there is a sheer sensitive material in the formulation.


● Order of Addition: Always follow the recommended order of adding ingredients. For

example, oils and water phases need to be heated separately and then combined under

mixing at specific temperatures.


● Timing: Some ingredients should be added at cool-down stages to preserve their

efficacy, such as certain actives and preservatives.


● Temperatures: Make sure you are using a thermometer when making cosmetics and

heat your phases to the recommended temperatures.

Understanding these factors and adjusting your approach accordingly can help you achieve

consistent, high-quality results in your formulations. Whether you’re a home formulator or a

professional, being mindful of ingredient differences, the impact of substitutions, and proper

mixing techniques will greatly improve your success in crafting effective and stable products.



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