At some point, you must have seen a cleaning product with a whitish or milky appearance. But do you know, in general terms, which raw material is responsible for this characteristic?

In cleaning product formulations, in addition to the raw materials essential for performance—such as surfactants, for example—additives are also included; these are components capable of altering certain commercial characteristics.

An opacifier is a styrene-based acrylic polymer whose sole function is to alter the product’s appearance, giving it a milky or whitish look. It is commonly used in disinfectants, dishwashing liquids, and laundry detergents.

Key considerations when using opacifiers

Using opacifiers without the proper knowledge can cause some headaches, as they can become unstable, leading to separation and sedimentation at the bottom of the product.

To gain a better understanding of how to use opacifiers, Macler’s SmartLab conducted a series of tests to determine the optimal conditions for their use.

Substance with a partition at the bottom

In addition to choosing a good supplier and a high-quality product, there are three key factors that must be taken into account: active ingredient, viscosity, and electrolyte content. A balance between these three factors is necessary to achieve good final polymer stability.

As the conductivity of the solution increases—that is, as salts such as sodium chloride or magnesium sulfate are added—there is a greater tendency for the polymer to become unstable, depending on the viscosity and active ingredient concentration of the formulation. The higher the viscosity and the greater the active ingredient concentration (primarily sulfonic acid), the more stable the opacifier will be.

Certain conditions that have been observed may serve as a warning when developing a formulation containing an opacifier:

Detergents:

1. Order of opacifier addition: It must be added after the salt has been added.

2. Minimum Viscosity:
Anionic active ingredients up to 4.0%: minimum viscosity of 450 cP;
Anionic active ingredients above 6.0%: do not require viscosity for stabilization.

3. Formulations that do not require salt in their composition do not present stability issues.

General-purpose disinfectants, cleaners, and all-purpose cleaners:

1. There are anionic and cationic opacifiers. To obtain a more versatile product that can be used in both detergents and disinfectants, look for a nonionic opacifier.
2. As long as the formulation does not contain any strongly electrolytic components, such as hydrogen peroxide, a good opacifier will not present any stability issues.
3. For formulations of concentrated cleaners and all-purpose cleaners or caustic degreasers, consult the supplier to understand the limitations of the specific system. However, in general, a good opacifier exhibits high stability in caustic and alkaline media.

Finally, there are many different suppliers and grades of opacifiers on the market. Whenever you purchase the product, conduct a stability test and observe its behavior in light of the points discussed above. This will help you separate the wheat from the chaff and save you a lot of headaches and product returns.

Would you like to learn about a high-stability opacifier?

Contact Macler and request a sample for approval.