PART 2: Why Emulsions Break & How to Keep Them Stable

Introduction

Even well-designed emulsions can fail if formulation balance or processing is incorrect. Understanding why emulsions break helps you prevent failure before it happens.

Why Do Emulsions Break?

1.     Wrong Emulsifier Selection

Incorrect HLB

O/W emulsifier used for W/O system

Insufficient emulsifier quantity

2.    Unbalanced Oil-to-Water Ratio

Too much oil

Heavy butters without support

Overloading actives

3.    Temperature Errors

Oil & water phases heated at different temperatures

Emulsifier not fully melted

4.    Improper Mixing

• Low shear mixing

• Incorrect phase addition

• Poor homogenisation

5.    pH & Electrolyte Stress

• pH outside emulsifier tolerance

• Clays, salts, acids, herbal extracts destabilising structure

6.    Preservation Failure

• Microbial growth weakens emulsion structure

• Leads to odour, thinning, separation

How to Keep Emulsions Stable (Best Practices)

• Match emulsifier to emulsion type

• Keep oil phase within emulsifier capacity

• Heat oil & water phases equally (65–75°C)

• Use correct mixing technique

• Add actives & preservatives below 40°C

• Adjust pH after full formulation

• Use broad-spectrum preservatives

• Perform stability testing

Stability Testing — Non-Negotiable

Test at:

• 5°C (cold)

• 25°C (room temperature)

• 45°C (accelerated)

Observe:

• Separation

• Viscosity change

• Colour & odour change

Stability is not accidental — it is designed.

In Part 3, we’ll cover how to fix broken emulsions and professional troubleshooting tools.