How to calculate the quantity of emulsifier needed in a formula

Emulsions are dispersions of liquid droplets in a liquid or semi-solid matrix. If the droplets consist of oil dispersed in an aqueous liquid it is oil-in-water (o/w) emulsions, and water-in-oil (w/o) emulsions are water dispersed in an oil matrix. The surfactant system stabilizes the interface and allows two phases to exist as a stable emulsion. This is achieved by stabilizing the aqueous (hydrophilic) and oil (lipophilic) components together as an emulsion formulation using the hydrophilic-lipophilic balance (HLB) system.

Creams and lotions are examples of emulsions. The term emulsifiers refer to any ingredient that helps to keep unlike substances (such as oil and water) from separating.

How to calculate the quantity of emulsifier needed when using a self-emulsifier

For most nonionic emulsifiers like emulsifying wax NF, silky wax, and tegocare 165,  the general rule of thumb is to use an emulsifier at 20-25% of the total oils in the formula.

These oils include fragrance, oil-based actives, butter, carrier oils, and essential oils.

1. Add up the oils in the oil phase and cool down phase to get the total oil
2. Calculate total oil divided by 100*20
3. Total oil divided by 100*25
4. Use emulsifying wax between the range gotten in 2 and 3 above

Total oil phase (rice bran oil, almond oil, d alpha-tocopherol, and fragrance ) = 18

18/100*20=3.6

18/100*25=4.5

The emulsifier can be used between 3.6-4.5% in your formula

Note:
Distilled water % is written as  QS (Quantum satis) which means the quantity of water that is enough to make your formula total  100.  Add up the total percentage and subtract from 100 to get the distilled water percentage usage rate for the formula.
For 4.5% emulsifier:
Total percentage = 27.5
100-27.5 = 72.5
Distilled water 72.5.

4.0% emulsifier :
Total percentage = 27
100-27 =73
Distilled water 73%

Tip:

One or more emulsifiers can be used in formulations. you can decide to use tegocare at 3% and silky wax at 1% to make up the 4% needed in the formula