Cosmetic Formulating Blog Series | Testing the Formula
Now that we went over some of the basics of cosmetic formulating and how to build the formula, let’s go over testing the formula. Cosmetic formulation testing is an important step before going to market with your final product.
Adjusting the Formula
It is rare that you will have the exact product you want on your first try. Formulating is all about tweaking your formula till you get it exactly how you want it. It takes a lot of patience. Don’t get discouraged if it is not turning out how you want, as it may just take a little tweak to get it exactly where you want it!
When making changes to the formula, it is important you only make one adjustment at a time. It can be tempting to make several changes at once, but then you will not know which adjustment produced what kind of change. It is also important to allow time for the formulation to settle. Sometimes scents can take time to evolve and waxes to firm up.
pH stands for “potential for hydrogen” and is the system to measure acid and alkaline. Neutral pH is 7, anything below 7 is acidic and anything above 7 is alkaline. Water has a neutral pH. The more acidic or alkaline a product is, the more it will cause irritation to the skin. Generally the pH level for body and skin care products should be between 4.5- 6.0 and for hair care products between 4.0- 6.0.
There are a couple different ways one can test for pH. There are pH strips that are easy to use. The strips will give a range instead of the exact pH. A pH meter on the other hand will give you the exact pH and is more accurate. You will likely need to adjust the pH of your product and you can do this with natural ingredients.
It is important for you to keep excellent records and label your sample with several key information. This includes the date it was made, type of product, pH, and a reference number that links to the formulation in your lab notebook to refer to for more detailed information. That way you can return to your sample over the next several months to test its stability. You should test the pH, notice the scent and how it has evolved, and if there has been any separation or discoloration.
Testing for Bacteria, Yeast and Mold
Any product that contains water will need to be tested for bacteria, yeast and mold. There are different ways to test your product.
Plate counts test if there is bacteria, yeast and mold in your sample. It will not tell you how long your preservation system will be effective.
Challenge testing is performed at at one month or two months. Millions of bacteria, yeast and mold will be injected into the product and it will determine if your preservation system is effective.
Stability Testing will test how your product reacts to very hot and cold temperatures.
Testing and Preservation Resources
It is very important to test your product and not only for the stability of the skin or hair care product, but also for bacteria, yeast and mold, and if the preservation system is effective. At Joan Morais Naturals we provide extensive information on testing and preserving your body and hair care products naturally and effectively in our professional product making courses. For information on these courses check out the following: