Raw material suppliers often give the suggested use level of ingredients. In reality, these are just estimations or motivated suggestions that don't necessarily reflect what would be best in your own formulation. Consider them good starting points, but to get to the final formula, you'll have to optimize the ingredient level yourself. Unless you’ve done this before, you won’t have an easy method. Here’s one you can follow.
We’ll assume that you have a standard base formula with which you are starting. This is pretty standard practice in the industry. It's even more difficult to optimize a raw material level if you have multiple new ingredients in the formula.
When adding a new raw material to your formula, the first thing you have to decide on is a starting level. To figure this out, you need to decide whether your driving force is performance or cost. On some level, it will be both but one of them should take prominence at first. Personally, I like to ignore cost in the beginning and focus on performance. I figure if a new material provides an impressive new benefit, the additional cost can be overcome through improved marketing.
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When focusing on performance the starting level should be the highest level suggested by the raw material supplier, or 1%, whichever is higher. The 1% level is nice to use because it is the maximum level you can use without affecting the ingredient list. The reason we say to use the supplier’s suggested level is because they will usually give the highest level they can. Suppliers are inclined to do this because they want to sell more product.
Make your batch
After you’ve figured out your starting level, make a batch with the new raw material. If you are working with a solution and a water soluble ingredient, you can post add the ingredient to a finished base. However, if it is a more complicated formula form like an emulsion or the ingredient is oil soluble, you should start from scratch.
While you're creating the prototype be sure to observe the effects the ingredient has on your formula (e.g. On appearance, viscosity, etc.)
Test with and without
After you’ve made your batch you should compare it to a sample of the base formula (without the ingredient). The exact test that you do depends on what the raw material is supposed to do. For example if you are testing a new moisturizing ingredient you can test how it feels on your skin. For a hair product ingredient you can compare performance for combing or feel on hair tresses. Ideally, you'll do these evaluations in a blinded manner to remove any bias. As a formulator you are motivated to create improved formulas and this can cloud your judgement in favor of the new ingredient.
If you can’t tell any difference at this point, it’s probably not worth going any further with the ingredient. There are a lot of ingredients out there so you don’t want to waste time on ones that don’t show any obvious differences at high levels.
Optimizing cosmetic raw material levels
If you find some type of formula improvement, great! The next thing you have to do is optimize the level of the ingredient. This is an iterative process but you can be most efficient if you follow the “half and double” technique.
To use the half and double technique, you simply make one batch where you cut the level of the ingredient in half and another where you double the level. So, if your starting level was 1% you would make one batch using 0.5% and another using 2%. Then you evaluate the samples (blinded) and see if you can tell a difference. If you can’t tell a difference between the samples, you can repeat the test a few times just to make sure you’re not missing something. But if you still can’t tell a difference, then use the lower level. Repeat the process of cutting the ingredient level in half or doubling it until you get to a point where you figure out the exact, optimized level. Using this process should get you to an optimized ingredient level within 7 batches.
While this method is focused on evaluating new raw materials it would work equally well with the ingredients in your current formula. If you have a formula in which you want to reduce the cost optimizing each ingredient (starting with the most expensive) is a great technique.
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