Here’s a word that gets bandied about quite often in formulation labs, because there’s really no other word that fit the thing it describes. Thixotropy is a property of certain gels or fluids that become less viscous (thinner) when subjected to shear stress, such as stirring, shaking, or squeezing, and then gradually return to their original, more viscous (thicker) state once the stress is removed. The best known example is non-drip paint – which spreads easily when subjected to the shear applied by a paintbrush running over the ceiling but as soon as that stress is removed.
Thixotropy is crucial consideration in personal care products because it allows products like creams, lotions, and gels to be easily applied when rubbed or pumped, making them spread smoothly and evenly on the skin. After application, these products regain their thicker consistency, providing a stable, long-lasting layer on the skin. This property is particularly beneficial for products like shampoos, conditioners, and serums, where controlled viscosity is essential for ease of use and product performance. A big chunk of a development project can often be considered to be simply the process of optimising the degree of thixotropy.
Advantages of Thixotropy In Personal Care Products
Thixotropy in personal care products offers several benefits and some drawbacks. One major advantage is that thixotropic products are easy to apply. They become less viscous when you squeeze or rub them, making them smooth and easy to spread on the skin or hair. This property also allows for controlled dispensing, as the products are thick and stable when at rest, preventing them from dripping or leaking, but they flow easily when used.
Another advantage is the stability they provide. After application, thixotropic products return to a thicker state, creating a stable, protective layer that stays in place. This reversible nature also enhances the sensory experience, giving a rich and luxurious feel during application without leaving a sticky or greasy residue. Additionally, thixotropic formulations offer flexibility in packaging options, as they can be used in pumps, tubes, or jars, flowing easily when dispensed but remaining stable otherwise.
Disadvantages of Thixotopy In Personal Care Products
However, there are some disadvantages. One potential issue is syneresis, where the liquid component of the product separates over time, leading to an inconsistent texture and reduced performance. Another challenge is that thixotropic products can feel different with each use, depending on how they’ve been handled, which can affect user experience. Lastly, environmental factors like temperature changes can alter the thixotropic behavior of a product, causing unexpected changes in viscosity and performance.
