HLB Demystified: A Formulator’s Guide to Emulsifier Selection

• What is HLB?

The Hydrophilic-Lipophilic Balance (HLB) scale (0–20) determines an emulsifier’s affinity for oil or water. Lower values (≤6) suit water-in-oil (W/O) emulsions, while higher values (≥8) work for oil-in-water (O/W).  

• HLB in Practice

- W/O Emulsions (HLB 3–6): Ideal for heavy creams or balms.  

  - Example: *Sorbitan Monostearate* (HLB 4.7).  

- O/W Emulsions (HLB 8–18): Used in lightweight lotions.  

  - Example: *Polysorbate 80* (HLB 15).  

• The HLB System in Action

To emulsify a blend of coconut oil (HLB 6) and water:  

1. Calculate the required HLB for the oil phase.  

2. Select emulsifiers matching the target (e.g., *Glyceryl Stearate SE* for HLB 11).  

• Common Pitfalls

- Phase Separation: Caused by mismatched HLB.  

- Grittiness: Incorrect cooling rates during emulsification.