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My emulsion keeps breaking at 40°C during stability testing. Formula is a w/o moisturiser with 30% oil phase including 5% Shea Butter and 3% Caprylic/Capric Triglyceride. Using Polyglyceryl-3 Diisostearate at 3% as primary emulsifier.

Formulation Partner

I've analysed this against 2,573 similar w/o systems in the knowledge base. Three likely causes, ranked by probability:

Emulsifier concentration insufficientHIGH

Polyglyceryl-3 Diisostearate at 3% is below the recommended 4–6% for a 30% oil phase w/o system. The HLB demand of your oil phase exceeds the emulsifier capacity at elevated temperature.

→ Increase to 5% and re-test. Consider adding Polyglyceryl-2 Sesquiisostearate at 1% as co-emulsifier.

Shea Butter melting point interferenceMEDIUM

Shea Butter melts at 32–38°C. At 40°C the oil phase viscosity drops sharply, reducing the physical stability of the interfacial film.

→ Replace 2% Shea Butter with Hydrogenated Shea Butter (mp 55–60°C) to maintain oil phase structure at test temperature.

Electrolyte interference from water phaseLOW

If water phase contains electrolytes (NaCl, preservative salts), these can destabilise the interfacial film in w/o systems.

→ Check water phase electrolyte load. Reduce if >0.5%.

Cross-reference: 94% of stable w/o systems in this oil load range use emulsifier concentrations of 4.5–6%. Your current 3% is at the 8th percentile.

Formulation Partner has access to 51,780+ ingredient records, 8,000+ reference formulations, and 550,000+ marketed products.

Failure Diagnosis

Emulsifier ConcentrationHIGH

3% Polyglyceryl-3 Diisostearate insufficient for 30% oil phase at elevated temperature. Recommended: 4.5–6%.

→ Increase to 5% + Polyglyceryl-2 Sesquiisostearate 1% co-emulsifier

Shea Butter Melt PointMEDIUM

Solid Shea melts 32–38°C, destabilising oil phase structure at test temperature.

→ Substitute Hydrogenated Shea Butter (mp 55–60°C)

Electrolyte LoadLOW

Check water phase electrolytes — >0.5% can destabilise w/o interfacial film.

→ Reduce electrolyte concentration if applicable

Cross-Reference

2,573 w/o emulsion systems analysed

94% of stable systems at this oil load use 4.5–6% emulsifier

Your system: 8th percentile for emulsifier concentration

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