PEG-40 Hydrogenated Castor Oil

PEG-40 Hydrogenated Castor Oil is a non-ionic surfactant primarily used as a solubiliser in cosmetic and personal-care formulations. It helps incorporate fragrance, essential oils and other suitable lipophilic materials into water-containing systems and is commonly used across aqueous and surfactant-based formulations.

What is PEG-40 Hydrogenated Castor Oil & why is it used?

PEG-40 Hydrogenated Castor Oil is produced from hydrogenated castor oil modified with polyethylene glycol (PEG), creating a non-ionic surface-active ingredient with both hydrophilic and lipophilic characteristics. This allows it to interact with oil-soluble materials while remaining compatible with predominantly aqueous formulation systems.

Formulators use PEG-40 Hydrogenated Castor Oil primarily to help distribute materials that would otherwise have limited compatibility with water, including fragrance, essential oils and other suitable lipophilic ingredients. By reducing the interfacial tension between oil- and water-associated components, it can help create more uniform dispersions and, where the formulation system allows, support improved clarity.

Its usefulness is not limited to simple water-and-fragrance systems. PEG-40 Hydrogenated Castor Oil can also be incorporated into surfactant-based formulations such as cleansers, shampoos and body washes, where the surrounding surfactants, oil load and other formulation components influence its final behaviour.

QUALITY MATTERS

Why specification quality matters

When selecting PEG-40 Hydrogenated Castor Oil for formulation, consider the material's grade, defined specification and available technical documentation rather than assuming all materials sold under the same INCI will have identical specifications.

For repeat formulation work, consistency of the raw material and appropriate batch documentation can be important when assessing changes in clarity, viscosity, sensory characteristics or finished-product stability.

Appearance Colourless to light yellow liquid

Solubility Water soluble

Primary function Solubiliser

Use level 0.5–3.0%

Key benefits

Solubilising

Helps incorporate suitable oil-soluble materials into predominantly water-based formulations.

Dispersing

Supports more uniform distribution of fragrance, essential oils and other compatible lipophilic materials.

Non-Ionic Functionality

Provides versatile surface-active functionality without carrying an ionic charge, making it useful across a broad range of cosmetic formulation systems.

Formulation Versatility

Can perform solubilising, dispersing and supporting emulsification roles across different cosmetic formulation types.

Behaviour in formulations

PEG-40 Hydrogenated Castor Oil acts at the interface between water and compatible lipophilic materials, helping distribute fragrance, essential oils and other oil-soluble components through aqueous formulations. Its performance depends on the material being solubilised, its concentration and the composition of the surrounding formulation.

The amount required is not determined by a universal solubiliser-to-oil ratio. Different fragrances and oils can behave very differently, while surfactants, electrolytes and other formulation components may also influence clarity, viscosity and stability. Formulators should therefore optimise the solubilising system experimentally for the finished formulation.

Sensory notes

PEG-40 Hydrogenated Castor Oil is generally used for its functional solubilising properties rather than as a primary sensory modifier. At appropriately optimised levels its sensory contribution may be relatively unobtrusive, while higher concentrations can have a more noticeable effect on the weight, tack or overall feel of lightweight formulations.

Sensory performance is formulation-dependent and should be assessed within the complete finished system.

Formulation considerations

PROCESSING

Pre-mix PEG-40 Hydrogenated Castor Oil thoroughly with the essential oil, fragrance or other suitable oil-soluble material at room temperature. Slowly add the premix into the water phase under continuous stirring until uniformly incorporated. Avoid overheating above 60°C during processing.

The required solubiliser-to-oil ratio will depend on the specific material being incorporated and the desired clarity and stability of the finished formulation. Confirm performance through formulation and stability testing.

COMPATIBILITY

As a non-ionic surfactant, PEG-40 Hydrogenated Castor Oil can be used across a broad range of cosmetic formulation systems. It is particularly useful in aqueous and surfactant-containing products.

Compatibility and solubilising performance can be influenced by the fragrance or oil being incorporated, other surfactants, electrolytes and the overall composition of the formulation. Compatibility should therefore be confirmed in the complete finished product.

PEG-40 Hydrogenated Castor Oil is not used primarily to control formulation pH. Finished-product pH should be selected according to the requirements of the complete formulation and the other ingredients present.

FORMULATION EXAMPLES

Facial Toner or Mist - Use to help incorporate a small amount of fragrance or compatible lipophilic material into a predominantly aqueous formulation. Optimise the solubilising system according to the material being incorporated and the desired clarity.

Water-Based Serum - Can provide solubilising support where a predominantly aqueous serum contains a compatible oil-soluble component that would otherwise have limited water compatibility.

Facial or Body Cleanser - Use within a surfactant system to help distribute fragrance or other suitable lipophilic ingredients. Consider the effect of the complete solubiliser, oil and surfactant system on clarity, viscosity and foam.

Shampoo or Body Wash - Can support incorporation and distribution of fragrance and compatible oil-soluble components within rinse-off surfactant formulations.

Use level considerations

Recommended range 0.5–3.0%

Suggested starting level 0.5%

The amount of PEG-40 Hydrogenated Castor Oil required depends on the type and concentration of fragrance, essential oil or other lipophilic material being incorporated, as well as the composition of the overall formulation. There is no universal solubiliser-to-oil ratio, as different oil-soluble materials can require substantially different levels to achieve the desired clarity and stability.

Formulators should begin with small-scale trials and optimise the ratio experimentally. Using more solubiliser is not necessarily better; excessive levels may influence clarity, viscosity, foam behaviour and finished-product sensory characteristics. The selected level should therefore balance effective solubilisation with the desired performance of the complete formulation.

For surfactant-based products, assess PEG-40 Hydrogenated Castor Oil as part of the complete surfactant and oil-soluble system, as interactions between these components can affect the final result. Finished formulations should be evaluated for appearance, homogeneity and stability over time.

Manufacturer guidance recommends 0.5–3.0% PEG-40 Hydrogenated Castor Oil, with approximately 2–3 times the amount of the oil component being solubilised provided as a starting guide. This ratio should be treated as a starting point rather than a fixed requirement, with the final level confirmed through formulation and stability testing.

Formulation summary

PEG-40 Hydrogenated Castor Oil is a versatile non-ionic solubiliser suited to aqueous and surfactant-based cosmetic formulations containing small amounts of fragrance, essential oils or other compatible lipophilic materials. Successful use depends on balancing the solubiliser with the specific material being incorporated and the wider formulation system rather than relying on a fixed universal ratio.