Article by: Perry Romanowski
There are many different routes you can take to learn to become an expert formulation chemist but few are more powerful than conducting your own knock-out experiments. These type of experiments can help you learn a number of things such as,
- 1. The function raw materials
- 2. The performance effect of raw materials
- 3. The formula effect of raw materials
It can also potentially lead to the discovery of a new formulation and cost savings ideas.
Formulation Chemist Knockout Experiment
The term knockout experiment was taken from the field of genetic engineering. In it, scientists create organisms in which they remove or “knock out” a specific gene. Then they see what effects the removal of a certain gene has on the organism.
In the cosmetic chemist’s version of a knockout experiment, you take a known formula and “knock out” a specific raw material. You then see what effect the absence of that raw material has on the final product. It’s a simple yet powerful study that can quickly get you familiar with any formula.
What will a cosmetic knockout experiment teach you?
When you first start your cosmetic formulating job, you will often start new projects with a formula that your company had previously developed. I remember the first formula I ever made (a shampoo) was originally developed by the guy whose notebook I inherited. My boss asked me to make samples to give to our Marketing group for evaluation. I had no clue about why any of the raw materials were used, what they did, or even how hard they were to work with.
You will undoubtedly be in the same position if you are just starting in this industry. Even if you’ve been around for a long time, it’s impossible to know the effect of raw materials in any formula you haven’t personally made (or observed being made).
Knockout experiments can rapidly tell you when making a batch exactly which ingredients have the most effect, which ones can be removed and which ones interact. When you’re done making the formulas, you can learn what raw materials have the most impact on the final specifications and the product performance.
The amount of information you can learn from a single knockout study makes it well worth doing on every new formula you are asked to work on.
How to conduct a cosmetic knockout experiment
Running a knockout experiment is fairly easy. All you have to do is take your initial formula and make a series of batches in which you remove one ingredient. If it’s a water-based formula, you simply add water to replace the missing mass.
Here is an example batch sheet for conducting a knockout experiment on a shampoo formula. (Click to enlarge) As you can see, each subsequent formula has a line where the value of one ingredient is supposed to be.
In this formula there are 8 unique ingredients which means you will need to make 8 different batches. The first batch is the control batch which should be made first. This ensures that you are able to successfully make the formula.
You should try to control as many variables as possible such as temperature, mixing speed, mixing time, etc.
Simplifying the knockout experiment
While it is best to make a new formula for each ingredient, this can become impractical and unproductive if there are dozens and dozens of different raw materials. In these cases you can minimize the number of batches to make by ignoring ingredients not expected to significantly impact the end performance such as
- 1. fragrance
- 2. dye
- 3. extracts
- 4. preservatives
If you don’t know which ingredients are superfluous, ask one of your more experienced peers. But be careful. It is wrong to make any assumptions about a formula. There could be ingredients you expect not to have any effect that do.
It’s worth noting that more complicated versions of this knockout experiment can be conducted using DOE (design of experiment) software. These experiments can give you much more information. Unfortunately, they also require many more batches to be made. In future articles we will discuss DOE further.
Evaluating your cosmetic knockout formulas
After you’ve made your batches you will end up with a series of formulas that need to be tested. At the very least you should take pH and viscosity measurements. You can then correlate the presence of any ingredient with an effect on those variables. This can be extremely useful if you need to help make adjustments on the production level in characteristics like pH, viscosity, texture, odor and appearance.
You should also conduct appropriate lab tests to see how the removal of a certain ingredient affects performance. For foaming products, conduct foam tests. For skin lotions, do a moisturizing test. Perhaps most important is to try the product out on yourself. Try to experience the product like a consumer. This will give you excellent clues about how important any raw material is to the overall effect of the formula.
Knockout your cosmetics
The knockout experiment is not a perfect way to learn all you can about a formula. There are important synergistic effects it will miss. That’s why DOE is often superior. However, you can’t beat knockout experiments for speed and ease. And you’ll definitely learn a lot about raw materials quickly. To become a great formulation chemist you have to make a lot of batches and try many different ingredients. The knockout experiment helps get you there faster.