Span 60 and Span 80 are widely used nonionic surfactants in cosmetic, pharmaceutical, and industrial formulations. Both function primarily as water-in-oil (W/O) emulsifiers, helping stabilize mixtures of oil and water. However, despite their similar functions, they differ in chemical composition, physical properties, and processing requirements.
Understanding these differences is essential when selecting a suitable emulsifier Span product for a specific formulation. The choice between Span 60 and Span 80 depends not only on emulsification requirements but also on processing temperature, desired consistency, and compatibility with other ingredients.
Span 60, chemically known as Sorbitan Monostearate, is a nonionic surfactant derived from sorbitan and stearic acid. Stearic acid is a saturated fatty acid, which contributes to Span 60's relatively high melting range and waxy consistency.
Span 80, or Sorbitan Monooleate, is produced using sorbitan and oleic acid. Unlike stearic acid, oleic acid contains a carbon-carbon double bond, giving Span 80 different physical characteristics, including its liquid state at room temperature.
Both products belong to the sorbitan ester family and have relatively low hydrophilic-lipophilic balance (HLB) values. They are commonly used as lipophilic emulsifiers and may be combined with higher-HLB surfactants to achieve specific emulsification requirements.
Although their functions overlap, their structural differences can influence how they behave during manufacturing and in finished formulations.
The following table summarizes their main characteristics based on commonly published technical specifications.
| Property | Span 60 | Span 80 |
| Chemical Name | Sorbitan Monostearate | Sorbitan Monooleate |
| CAS Number | 1338-41-6 | 1338-43-8 |
| Fatty Acid Component | Stearic acid | Oleic acid |
| Fatty Acid Structure | Saturated | Monounsaturated |
| Appearance at 25°C | Waxy solid, beads or flakes | Yellowish to amber oily liquid |
| Typical HLB Value | 4.7 | 4.3 |
| Surfactant Type | Nonionic | Nonionic |
| Typical Emulsifying Function | W/O emulsifier | W/O emulsifier |
Note: HLB values and appearances represent typical commercial grades. Actual product specifications should be confirmed using the manufacturer's Technical Data Sheet (TDS).
One of the most practical differences is their physical state.
Span 60 is generally solid at room temperature and may require heating before incorporation into a formulation. Its waxy nature can also contribute to the consistency of certain cream-based systems, depending on the overall composition.
Span 80 remains liquid at room temperature, making it easier to measure, transfer, and incorporate into liquid formulations. This can be advantageous when processing conditions do not allow additional heating.
Span 60 has a typical HLB value of 4.7, while Span 80 has a slightly lower value of 4.3. Both are predominantly lipophilic and commonly used in W/O emulsification.
However, this small numerical difference does not mean Span 80 automatically provides better W/O emulsification. Actual performance depends on the oil phase, emulsifier concentration, processing conditions, and other ingredients.
Both products can also be combined with higher-HLB emulsifiers, such as suitable Tween grades, to create emulsifying systems for oil-in-water (O/W) formulations.
Selecting the right emulsifier requires considering the formulation's intended application and manufacturing process rather than relying on HLB values alone.
Span 60 is worth considering when developing cream-based formulations or systems where a solid emulsifier can be incorporated through controlled heating.
It is commonly used in cosmetic creams, lotions, and certain pharmaceutical formulations. When combined with appropriate co-emulsifiers and structuring ingredients, it can contribute to emulsion stability and desirable product consistency.
Span 80 is often a practical choice for liquid formulations, oil-based dispersions, and applications requiring a readily incorporated liquid surfactant.
Its physical form makes it convenient for various industrial processing systems, including selected lubricant formulations, cosmetic products, and pharmaceutical emulsions.
For processes where minimizing heating is important, Span 80 may offer greater handling convenience.
Although Span 60 and Span 80 have similar emulsifying functions, they should not be considered direct substitutes in every formulation.
Replacing one with the other may affect processing temperature, viscosity, ingredient compatibility, and long-term emulsion stability.
Before making a substitution, formulation testing is recommended to evaluate the final product's appearance, consistency, and stability under intended storage conditions.
Ultimately, choosing between Span 60 and Span 80 involves balancing emulsification performance with practical manufacturing requirements. Reviewing the relevant TDS and conducting small-scale formulation trials can help identify the most suitable product.
