Tool
HLB calculator guide
The Apothecary Os is the first formulation OS built for melanated skin and hair — the HLB calculator is how you stop your lotion from splitting the second week.
Why HLB matters
A lotion that separates isn't just cosmetic — it's a signal the preservative distribution is off too, which means bacterial risk. Getting HLB right is the difference between a 3-day emulsion and a 12-month shelf-stable product.
Typical rHLB by product type
- Light face lotion — rHLB 7–10
- Body lotion — rHLB 8–11
- Rich cream / balm — rHLB 6–8
- Sunscreen (mineral) — rHLB 8–12
- Hair conditioner — rHLB 5–7
Frequently asked
What is HLB?
Hydrophilic-Lipophilic Balance — a 0–20 scale that describes how water-loving or oil-loving an emulsifier is. Every oil blend has a 'required HLB' to emulsify stably. Match your emulsifier to that number and your lotion won't split.
How do I find the required HLB of my oil phase?
Weight-average each oil's rHLB by its percentage. Our HLB calculator does this automatically and suggests emulsifier blends that hit the target.
Which emulsifiers work for cold-process formulas?
Olivem 1000, Ecomulse (Ritamulse SCG), and Emulsimulse are the most popular cold-process picks. Cetearyl alcohol pairs well with all three as a co-emulsifier and thickener.
Why did my lotion split anyway?
Common culprits: HLB mismatch, insufficient shear during emulsification, phase temperatures more than 5°C apart, or a preservative added too hot. Use the stability tool to isolate which one.