Thickeners play a vital role in the cosmetics industry. They increase the viscosity and thickness of cosmetic formulations. These substances give a product the desired consistency and performance profile.
Besides controlling flow and rheological properties, thickeners exhibit:
- improved spreadability
- prevents particle separation & phase separation
- increased emulsion stability
- sensory characteristics
Kinds of thickeners:
- Natural thickeners like Xanthan gum, Guar gum, and Hydroxyethyl cellulose
- Synthetic thickeners like Carbomer
- Associative thickeners like Acrylate/C10-30 alkyl acrylate
Choosing the right thickener is very important to create an effective product.
The most important issues for choosing right thickener in formulation are:
1-Compatibility with other ingredients in formulation
Thickeners must be compatible with other components of the formulation. Incompatibility can lead to several issues.
1-1-Phase separation: Phase separation refers to the separation of different phases within the formulation. It results in the formation of distinct layers or visible boundaries. It occurs when the chosen thickener is incompatible with base ingredients such as oils, emollients and solvents; surfactants, preservatives, active ingredients such as antioxidants, sunscreen agents; pH levels of the formulation. Phase separation can impact the: stability, appearance, and performance of the product.
Factors influencing phase separation are: Incompatibility with emulsifiers, Improper balance of oil and water phases, Chemical interactions affecting stability, and Inadequate compatibility with formulation pH
Demerits of phase separation:
Compromised stability: Phase separation leads to an unstable formulation. Such formulation is prone to separation. It changes in texture over time. The lack of stability affects the shelf life of the product. It can result in inconsistent performance upon application.
Undesirable appearance: Phase separation can cause the formulation to appear visually unappealing. The formation of distinct layers or boundaries is displeasing. This can impact consumer perception and acceptance of the product
Altered texture and sensory attributes: The separation of phases can result in changes in texture, consistency, and sensory attributes of the formulation. This can lead to a compromised user experience. The product may feel grainy, uneven, or unpleasant on the skin.
1-2- Ingredient inactivation: This can occur in cosmetic formulations when the chosen thickener is incompatible with other formulation components. This leads to reduced efficacy. It can alter the properties of the active ingredients. This can compromise the performance and desired benefits of the product.
Factors influencing ingredient inactivation are: Chemical interactions, pH-dependent interactions, Binding or encapsulation effects, and Instability in formulation
Demerits of ingredient inactivation:
Reduced efficacy: It causes ingredient inactivation of the active ingredients. This leads to diminished product performance. The desired benefits may not be achieved at their intended levels. For e.g., moisturization, anti-aging effects, or UV protection.
Altered properties: Incompatibility with the thickener can alter the properties of the active ingredients. For e.g., changes in solubility, stability, or release profiles. Altered properties can affect the bioavailability and delivery of the active ingredient. This leads to compromised functionality.
Decreased shelf life: Incompatibility can lead to decreased stability of the formulation over time. This can result in a shorter shelf life for the product. This is because the active ingredients may degrade or lose their potency due to incompatibility.
1-3- Compromised stability: This occurs when the chosen thickener is incompatible with other formulation components. It is a significant concern in cosmetic formulations. It can result in various issues that affect the performance, appearance, and shelf life of the product.
Factors influencing compromised stability are: Viscosity control in the formulation, Navigating texture alteration, Changes in color and fragrance, Stability during storage, and Degradation of ingredients
2-Compatibility testing:
Compatibility testing is recommended to address phase separation, ingredient inactivation, and compromised stability. It ensures compatibility between thickener and other formulation components. Various methods help to identify incompatibilities or potential formulation issues.
These include:
Visual inspection: Visual inspection involves observing the formulation for changes. These include changes in appearance, such as color changes, phase separation, or the formation of sediments. This initial assessment can provide valuable indications of compatibility issues. Incompatibilities may manifest in various ways. For e.g., changes in clarity, homogeneity, or visual appearance of the formulation
Stability testing: In stability testing, the formulation is subjected to various conditions. This test evaluates the physical and chemical stability. For e.g., temperature variations, freeze-thaw cycles, and prolonged storage periods. Stability tests can help identify any potential issues that may arise during the product’s shelf life. Common stability tests include: Freeze-thaw stability, Accelerated stability testing, and Long-term stability testing
physical property analysis: Physical property analysis involves evaluating specific characteristics of the formulation. It enables to identify changes or issues caused by the thickener. Some common physical property analysis methods include: pH measurement, Viscosity measurement, Rheological analysis
Various Types of Instability Observed in Different Formulations
(F1) Congealing & Creaming; (F2) Formation of Lumps & Phase Separation; (F3) Oil Separation; (F4) Stable Moisturizing Cream; (F5) Stable Moistirizing Lotion
