The cosmetics industry racked up sales of about $170 billion last year. That may seem like a lot of liquid eye liner, but the segment still shows strong rates of growth. Underlying every successful cosmetic product is the ability to deliver consistent quality every time it’s purchased by a consumer. Understanding how moisture affects quality can help you achieve the quality your customers demand. If you need a refresher on how moisture and water activity are related.
The Power of Powder
Many cosmetics products are compacted tinted powders. The compaction and flow properties of these substances are controlled by water activity. During the manufacturing process, knowing the critical water activity of your powder can assure that your equipment isn’t loaded full of a powder that won’t move. When the blended powder is ready to be formed into the packaging, the water activity influences how tightly the powder is compacted. Any variation in your product’s water activity will affect its physical properties.
Read more about physical properties and water activity >>
Bacteria and Cosmetics
Water activity, and not moisture content, determines what bacteria can grow in your product. Cosmetics tainted with bacteria can cause irritations and infections on the skin and in eyes. Even if your products comply with GMP requirements, your customers may not be as careful. Formulating your product with a water activity below 0.87 aw will guarantee that even if it picks up trace amounts of bacteria during use, the bacteria won’t grow.
Learn how water activity controls microbial growth >>
Many cosmetics manufacturers monitor the moisture content of their products. Why? That’s what they’ve always done. For a particular product, water activity and moisture are linked: if one goes up, so does the other. So even if you just want a better way to measure moisture, water activity can give it to you. Why?
- Water activity meters are much more sensitive to changes in moisture than most moisture content meters. This is because on dry cosmetic products, a tiny change in moisture creates a large change in water activity. When compared with AOAC approved moisture methods like oven drying, water activity gives you about 10x more precision.
- Karl Fischer titrations are renowned for their precision, but lack speed, ease of use, and affordability. A water activity test gives you the precision of Karl Fischer without the costly reagents, glassware, and specialized trainin