Neem oil, like most other oils, will not mix with water. An emulsifier allows the oil to mix with water for use in sprays etc. Whilst you could use a conventional 'chemical' detergent we recommend Neemteam Eco-friendly gentle emulsifier for use with neem oil.
Eco-friendly gentle emulsifier is an effective mix of two of the most gentle & eco-friendly plant derived biodegradable detergents available.
98% biodegradable & recommended by the Swedish Environmental Protection Agency.