Benzalkonium chloride and zinc oxide cream

Avoid mixing air into emulsion. Emulsify under vacuum to minimize air entrapment. Use jacketed tank with vacuum with high-speed agitator and an adjustable slow-speed anchor type with Teflon sweep blades. 

If necessary, mill zinc oxide in a Fitz mill or similar impact-forward, maximum-speed mill, fitted with a 250-pm aperture screen. Repeat three times. Heat 800 mL of water to 75°C in a steam-jacketed mixing tank and dissolve methylparaben. 

Maintain temperature at 75°C. Disperse milled zinc oxide in solution of stepabove. Maintain temperature at 75°C. 

Dissolve benzalkonium chloride and glycerin in solution maintain temperature at 75°C. 

In a separate steam jacketed tank, add Polawax, cetostearyl alcohol, acetylated lanolin, oil-neutral vegetable triglycerides mixture, and propylparaben, and carefully melt at 70°C. 

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