The impact of temperature on formulations: understanding cloud and turbidity points

In chemical formulations, every detail counts, and temperature is one of the factors that can directly affect the stability and final appearance of a product.

In systems that combine surfactants, solvents, salts, and additives, such as detergents, cleaners, and fabric softeners, temperature variations can completely alter the behavior of the formula.

When the temperature changes, turbidity, phase separation, crystal formation, or changes in viscosity may occur.

Two parameters are critical in this analysis: the fog point and the cloud point. Both help the formulator predict the product's behavior across different temperature ranges.

Fog point

The fog point is the temperature at which a non-ionic surfactant begins to lose solubility, making the formulation visibly cloudy.

This behavior occurs because, with increasing temperature, the hydrophilic/ethoxylated part of the surfactant loses its affinity for water due to the breaking of hydrogen bonds, causing the micelles to begin to disorganize and the surfactant to behave like an oil. The result is the appearance of what is called a "mist," a visual indication that the system has exceeded its solubility limit, separating the surfactant from the water and, over time, separating into phases.

In practice, this can occur in products exposed to heat during transport or stored in hot locations, resulting in noticeable turbidity. In truck transport, in hot regions like the North and Northeast of Brazil, which easily reach 40°C, the temperature inside the truck can reach between 50 and 55°C. Therefore, the product must withstand these temperatures without becoming cloudy or separating.

Therefore, it is recommended that, in the case of formulations containing non-ionic surfactants, the cloud point be above 50ºC.

In the Macler Academy technical video, the determination of the cloud point is demonstrated in a laboratory:

The cloud point can be used as a quality control parameter both in the release of batches to be packaged and marketed, and in the receipt of non-ionic surfactants as a parameter to understand if there have been variations in solubility in the surfactant molecule.

Knowing how to identify this point enables the design of more stable formulations, especially in warm climates, ensuring that the product maintains a clear and homogeneous appearance over time.

Cloud point

While the cloud point indicates the solubility limit of a non-ionic surfactant, due to the breaking of hydrogen bonds between the ethoxylated/hydrophilic part and water, the cloud point indicates another mechanism of insolubilization.

Anionic surfactants, which contain salts in their molecular structure, begin to become insoluble when subjected to lower temperatures. When this occurs, the salts crystallize and precipitate. This is similar to what happens if we dissolve a good amount of table salt in hot water: when the water cools, some of the salt recrystallizes and precipitates. The cloud point is precisely the temperature at which this recrystallization phenomenon of the saline ingredients in the formulation begins to occur.

Below this temperature, these components become so insoluble that they precipitate, forming a white or colored background, as they may also carry the dye. This behavior is common in products stored in cold places or subjected to thermal cycles during transport.

The ideal cloud point temperature can vary depending on the region where the product will be marketed. If it is marketed in the south of the country, where the winter is more severe, it is usually recommended to work with a maximum cloud point of 0ºC. If it is in the Northeast, where the climate is warmer, a maximum cloud point between 10 and 12ºC can be used.

In the Macler Academy technical video, the method for determining the cloud point is presented practically:

Identifying this point is essential to prevent instabilities that could compromise the perceived quality of the product, even if its technical performance is not affected.

It is a fundamental measure both in Quality Control for releasing product batches and analyzing the impact of raw materials such as Sulfonic Acid and Sodium Lauryl Ether Sulfate on the formulation, as well as in Research and Development of new formulations, identifying, for example, the ideal salt concentrations in detergents, as shown in the video available from Macler Academy:

Why are these parameters fundamental?

Understanding the thermal behavior of a formulation goes beyond aesthetics.

The haze and cloudiness directly impact:

• Appearance and perception of quality: A cloudy product can be interpreted as unstable, even when functionally correct.
• Technical performance: Changes in micellar structure or in the solubility of additives can alter foam, viscosity, and detergency.
• Logistical stability: Knowing the temperature limits prevents surprises during transport or storage in different regions of the country.

These analyses help the formulator define safe operating margins, ensuring the product remains stable under real-world conditions of use.

Fog and cloud points are allies of the formulator, as they reveal how components interact in different scenarios. Measuring and adjusting these parameters in the laboratory for each batch is essential for safely releasing products and maintaining credibility in the market.

At Macler's SmartLab, these and other stability tests are conducted with technical rigor and state-of-the-art infrastructure, ensuring that each formulation is evaluated under real-world conditions. Contact us and discover the advantages of having Macler as your strategic chemical partner.