Using Knockout Experiments to reduce formula costs
I don’t know how I stumbled on the knockout experiment but it is by far the most useful formulation exercise. I think I was inspired by reading about knockout mice while I was studying biochemistry. Anyway, I encourage every cosmetic formulator to go through the knockout experiment exercise with any formula on which they are working. While it is not as thorough as the DOT method it provides you nearly as much information with much less effort. 
Cost Saving cosmetics
If you are tasked with reducing the cost of your formulation, there is nothing better than a knockout experiment to figuring out which ingredients you can cut and which to leave alone. Here is how you would do it.
Step 1 - Figure out cost contributions
Of course, the first thing you have to do is figure out which ingredients add the most to the cost of your formula. You can see how to do that in this post we previously wrote about cosmetic formula cost savings. This shows you how to determine exactly how much each raw material adds to the overall cost of the formula.
Step 2 - Conduct your knockout experiment
Next, you have to set up your knockout experiment in which you make batches knocking out the ingredients that have the highest impact on cost. There is no need to conduct knockout tests on ingredients that don’t contribute much to the final cost. If you don’t notice a significant cost savings by the complete elimination of an ingredient than there is no reason to do a knockout formula of that ingredient. That is just unnecessary, extra work.
Step 3 - Determine impact of ingredient removal
After you have made your batches figure out which ingredients had a significant impact on the formula. Things like fragrance and surfactants will have obvious effects but other ingredients like polymers may have less noticeable ones. You should conduct standard lab tests to ensure the formula still meets specifications. When you find a formulation that has potential, you should also have panelists test it to see if they notice things that aren’t obvious in a lab. Small changes can have consumer detectable impacts.
Step 4 - Optimize your formula
Once you’ve figured out the impact of the removal of an ingredient and its effect on price, you can try to make formulations where you add back a little of the ingredient. Remember everything you add back adds cost so if you are trying to cost reduce a formula you want to keep additions at a minimum. Using the half and double optimization trick is useful in this regard.
Knockout experiments are useful for many reasons for a cosmetic formulator. Cost savings is perhaps one of the most significant. I once used this exact technique to discover a $300,000 a year cost savings for a hair conditioner formula. Every cosmetic chemist should try it.
