In parts 1, 2, and 3 of this series, we talked about how fragrances are created by Fragrance Houses and sent to cosmetic manufacturers. In the fourth and final part we`ll talk about the issues chemists face when putting a fragrance into a finished product.
Adding Fragrance
Adding fragrance to a shampoo, body lotion, facial cleanser, or any other product, is not as easy as you might think. Chemists must first ensure that the fragrance can be properly mixed into the formula base. This may be tricky because fragrances are oily materials and may not be fully soluble in all types of formulas. If this is the case, additional chemicals called solubilizing agents can be added. (If you read the back of the bottle, a solubilizer typically looks like like “Polysorbate” followed by a number. ) Chemists must also make sure that the fragrance is added to the product at the right temperature or the scent might not smell right. Some products are heated during manufacture because many cosmetic ingredients have to must be melted before they can be used. Since fragrances are very temperature sensitive, this can be a problem. To avoid damaging the fragrance, formulators add fragrance after they`re done heating the product.
Testing The Finished Product
Even after the fragrance is in the product, a lot can go wrong. For example, the ingredients in the formula can change the way the fragrance smells or the fragrance can cause the product to become cloudy or change color. So, once the chemist has properly incorporated the fragrance into the product, they use a process called stability testing to look for incompatibility between the fragrance and the formula. This process can take a month or more and involves testing samples that have been stored at elevated temperatures and exposed to UV light. These conditions accelerate the kinds of reactions that cause chemical changes.
During stability testing chemists look for any changes to the product. One of the most common types of change caused by a fragrance interaction is a change in viscosity. Some formulas will get thicker or thinner than they are supposed to be because of an interaction with a component of the fragrance. Fragrance can also affect a product`s appearance. Fragrances have been known to turn a body wash from blue to green, or a conditioner from white to pink. They can also make a clear product, like a hair gel, turn cloudy or hazy. And fragrances can make creamy products, like hand lotions and suncreens, look grainy or even fall apart. Of course, the formulator also has to smell the product to make sure that the fragrance is not becoming distorted over time. That can happen because fragrances contain chemicals that are very reactive like ketones, aldehydes, esters, amides and alkynes.
Trouble Shooting
Depending on what goes wrong during stability testing, the chemist may attempt to fix the problem by adjusting the formula. For example, a shift in viscosity can be compensated for by adding a thickening or thinning agent. (Common table salt is widely used to thicken shampoo and body wash formulas.) If the problem is more serious, the chemist may also ask the fragrance house to modify the fragrance oil to resolve the issue. To arrive at a final fragrance and formula combination, the chemist and fragrance house may have to experiment with several versions of the fragrance. After each fragrance revision, stability testing is repeated until the product is finally proven it`s ready to be sold.
Alls Well That Ends Smell
As you have seen in this 4 part series, creating a fragrance and adding it to a cosmetic product is a complex process that requires both scientific and artistic skills. But thanks to the diligent efforts of the cosmetic chemists in the personal care industry, we`re blessed with thousands of great hair and skin products that work great and are fun to smell!








