If you work with emulsifiers, you've likely come across Span 60 and Tween 60 in the same breath. They sound similar, they're often listed side by side in formulation guides, and buyers frequently ask which one is "better." The short answer: neither is better — they serve different, often complementary, roles. Understanding what separates them will help you choose the right one (or the right combination) for your application.
Span 60 and Tween 60 both belong to the sorbitan ester family of nonionic surfactants, and they share the same starting material: sorbitan monostearate. The difference lies in one additional processing step.
Span 60 (sorbitan monostearate) is the base ester — sorbitan reacted with stearic acid. It is lipophilic, meaning it has a stronger affinity for oil than for water. Physically, it typically appears as a cream-to-tan colored waxy solid or flake at room temperature, and it disperses readily into oil phases but not into water.
Tween 60 (polysorbate 60) takes that same sorbitan monostearate backbone and adds polyoxyethylene (PEG) chains through ethoxylation. This extra step changes its behavior dramatically: it becomes hydrophilic, dissolving easily in water. Physically, Tween 60 is usually a lemon-to-amber colored liquid, paste, or semi-gel, depending on temperature and grade.
This one structural difference — the presence or absence of PEG chains — is what drives every practical distinction between the two products.
The most important number to know when comparing these two is the HLB value (Hydrophile-Lipophile Balance), which predicts how a surfactant will behave in a mixed oil-water system.
Span 60 has an HLB of approximately 4.7, placing it firmly in the water-in-oil (W/O) emulsifier range. It is used when the goal is to disperse small water droplets within a continuous oil phase.
Tween 60 has an HLB of approximately 14.9, placing it in the oil-in-water (O/W) range. It is used when small oil droplets need to be stably dispersed within a continuous water phase — the more common emulsion type in creams, lotions, and beverages.
Span 60 dissolves in oils, mineral oil, and most organic solvents but is insoluble in water. Tween 60 dissolves readily in water and many polar solvents but has limited solubility in oils. This solubility split is exactly why the two are frequently paired: each one anchors a different phase of the emulsion, and together they stabilize the interface between oil and water far more effectively than either could alone.
Span 60 is commonly used in W/O creams and ointments, anhydrous formulations, lubricants, and certain food products such as chocolate coatings and non-dairy creamers, where it helps control fat crystallization and texture.
Tween 60 is widely used in O/W lotions, pharmaceutical suspensions and emulsions, food emulsification (ice cream, baked goods, whipped toppings), and as a solubilizer for oil-soluble vitamins and flavors in aqueous systems.
| Property | Span 60 | Tween 60 |
|---|---|---|
| Chemical base | Sorbitan monostearate | Ethoxylated sorbitan monostearate |
| HLB value | ~4.7 | ~14.9 |
| Solubility | Oil-soluble | Water-soluble |
| Emulsion type | Water-in-oil (W/O) | Oil-in-water (O/W) |
| Physical form | Waxy solid/flake | Liquid or paste |
The right choice depends entirely on the emulsion type your formulation requires, not on which product is inherently "stronger" or "higher quality."
If your target product is a water-in-oil system — such as a barrier cream, an anhydrous ointment, or certain industrial lubricants — Span 60 alone may be sufficient. If your target is an oil-in-water system, such as a lightweight lotion or a beverage emulsion, Tween 60 is the more natural starting point.
In many real-world formulations, however, the two are blended rather than used in isolation. Combining a lipophilic emulsifier like Span 60 with a hydrophilic one like Tween 60 allows formulators to fine-tune the overall HLB of the emulsifier system to match the specific oil phase being used, since different oils and waxes require different HLB values for optimal stability. This blending approach — sometimes called the required HLB (RHLB) method — is standard practice in cosmetic creams, pharmaceutical emulsions, and many food products, and it often produces more stable, finer-textured emulsions than either surfactant used on its own.
For buyers and formulators, the practical takeaway is this: start by identifying the emulsion type and the HLB requirement of your oil phase, then select Span 60, Tween 60, or a blend of both accordingly. Product datasheets from your supplier should specify exact HLB values, saponification numbers, and recommended usage levels to help you dial in the right ratio for your application.
Span 60 and Tween 60 aren't competitors — they're two halves of the same emulsification toolkit, and knowing when to use one, the other, or both is what separates a stable formulation from one that fails on the shelf.
