LAB NOTES & SAFETY NOTICE
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Emulsifiers are substances whose role is to keep water and oils together in a lotion. They can do this because they have a double affinity: part of the molecule is hydrophilic (water-loving) and part is lipophilic (oil-loving). Thanks to this dual nature, two liquids that would normally separate are able to stay combined.
This double affinity, however, is not the same for all emulsifiers. Some tend to be more hydrophilic, others more lipophilic. The value used to describe this balance is called HLB, which stands for hydrophilic–lipophilic balance.
[If you feel like skipping the more technical part… feel free 😄 A bit further down things get much simpler. For those who enjoy going a little deeper, keep reading!]
What the HLB value tells us
The HLB scale ranges from 0 to 20 and gives a numerical indication of how hydrophilic or lipophilic a material is.
There are many charts and tables that try to associate specific properties with exact HLB ranges. In practice, these can sometimes be contradictory or confusing. What follows is a simplified summary of the general idea that appears most consistently across sources:
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HLB 0–3
Materials in this range are strongly lipophilic and are often better described as thickeners rather than true emulsifiers. -
HLB 3–6
These emulsifiers are still predominantly lipophilic and are commonly associated with W/O (water-in-oil) systems. -
HLB 8–16
Emulsifiers in this range are more hydrophilic and are typically linked to O/W (oil-in-water) systems.
A quick note on O/W and W/O emulsions
When oils and water are combined, different types of emulsions can form.
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In an O/W (oil-in-water) emulsion, oil droplets are dispersed within water.
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In a W/O (water-in-oil) emulsion, water droplets are dispersed within oil.
More complex systems also exist (such as W/O/W or O/W/O), but those are a topic for another time.
The most common type used in creams and lotions is oil-in-water (O/W).
Hydrophilic vs. lipophilic emulsifiers
In general terms, emulsifiers tend to lean either toward the hydrophilic or the lipophilic side. In many O/W creams, stability is often associated with the presence of both types: a more hydrophilic emulsifier and a more lipophilic one acting as a co-emulsifier.
It’s also worth mentioning that some emulsifiers are sold as self-emulsifiers. These already contain both hydrophilic and lipophilic components, which is why they are often described as being able to work on their own.
Examples of common emulsifiers and HLB values
Below is a list of commonly encountered emulsifiers along with their approximate HLB values. This is meant as a reference point rather than a strict classification.
3.5–4.0 – Glyceryl stearate (W/O)
4.0 – Lecithin (food-grade, commonly found in supermarkets)
4.7 – Cetearyl alcohol (W/O, lipophilic co-emulsifier)
5.0 – Cetyl alcohol (W/O, lipophilic co-emulsifier)
5.8 – Glyceryl stearate
6.5 – Polyglyceryl-3 oleate (intermediate properties)
9.7 – Lecithin (modified cosmetic grade, O/W)
10.0 – Montanov 68 (O/W, self-emulsifier)
10.0 – Abil Care 85 (O/W)
11.0 – Cetearyl glucoside (O/W)
11.5 – Polyglyceryl-3 methylglucose distearate
12.0 – Methylglucose sesquistearate (O/W)
13.0 – PEG-40 hydrogenated castor oil (O/W emulsifier and solubilizer)
15.0 – Polyglyceryl-10 laurate (O/W emulsifier and solubilizer)
16.7 – Polysorbate 20 (O/W emulsifier and solubilizer)
What HLB does not tell us
While the HLB value gives useful insight into how an emulsifier interacts with oils and water, it doesn’t answer several other important questions, such as:
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whether the emulsifier is typically used with heat or at room temperature,
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or how strong it is relative to other emulsifiers with a similar HLB.
These aspects depend on the specific material and are usually clarified through supplier documentation and practical experience.
(to be continued… 😄)
IT'S ALL IN MY HANDS 
do you have a preference when it comes to o/w or w/o? does it not matter or do they each have advantages?
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They are very different. The great majority of creams, lotions and even thick body butters are o/w.
O/w are the most versatile.
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