{"id":17183,"date":"2024-05-15T06:00:45","date_gmt":"2024-05-15T12:00:45","guid":{"rendered":"https:\/\/www.ulprospector.com\/knowledge\/?p=17183"},"modified":"2024-04-22T12:23:00","modified_gmt":"2024-04-22T18:23:00","slug":"pcc-the-role-of-humectants-in-cosmetic-formulations","status":"publish","type":"post","link":"https:\/\/ulprospector.ul.com\/17183\/pcc-the-role-of-humectants-in-cosmetic-formulations\/","title":{"rendered":"The Role of Humectants in Cosmetic Formulations"},"content":{"rendered":"

\"PhotoIf you leave French bread on the counter for a couple days, it will get stale and crumbly, however, if you do the same with banana bread, it remains moist. There are a few explanations for this but one of the main reasons is because banana bread contains a high level of sugars that are able to bind water so that it doesn’t evaporate. This phenomena, called hygroscopy, is characteristic of humectants<\/a> which are ingredients<\/a> used in formulation situations where you want to maintain water. There are numerous applications for humectants in formulating among which include skin and hair moisturization, product preservation, solubilization and more. Let’s look at these in a little more depth.<\/p>\n

Moisturization<\/strong><\/p>\n

Humectants<\/a> in skin and hair products are typically there for their conditioning effects because they can improve the look and feel of biological surfaces. They do this by attracting and maintaining water in skin and hair.<\/p>\n

The reason humectants<\/a> are hygroscopic is because of their molecular composition. While there are both organic and inorganic materials considered humectants, organic humectants are primarily used in the cosmetic industry. And when I say \u2018organic\u2019 I mean organic in the way that chemists use the term, a hydrocarbon. It has nothing to do with how the raw materials were farmed.<\/p>\n

Structure of humectants<\/strong><\/p>\n

The molecular structure of humectants<\/a> varies widely, but they all have multiple hydrophilic sites that can attract water molecules through the process of hydrogen bonding. For the most part, cosmetic humectants are polar molecules compatible with water and frequently contain -OH groups or -NH groups.<\/p>\n

The way humectants<\/a> work is that they attract water from either the atmosphere or from the body and bind it to itself via hydrogen bonding. The level of hygroscopicity can be measured for any kind of humectant. The amount of water that a material can bind at a specific humidity is called the equilibrium hygroscopicity. It is determined by placing a known quantity of a material in a fixed humidity chamber then measuring the change in mass of the material.<\/p>\n

When this test is done on a common humectant like Glycerin<\/a> you find that it will absorb 25% of its weight in water when exposed to 50% humidity.\u00a0 Under the same conditions another common humectant, Propylene Glycol<\/a> will absorb 20% its weight in water.\u00a0 In general, the more moisture a humectant absorbs, the better a humectant it makes for formulations.<\/p>\n

Ideal cosmetic humectants<\/strong><\/p>\n

Although many materials have humectant properties, not all of them work well in cosmetics. There are a variety of characteristics we look for when choosing cosmetic humectants<\/a>. These include\u2026<\/p>\n