When a recipe says use a preservative as directed: Every preservative has its own directions as to what percent it should be used at. Our Geogard 221 is used at around 0.5%. If you use another preservative, use it as directed by the supplier.
At small quantities, mls and grams are similar.
Scales that measure in increments of 0.1g are the best. Buy ones that measure in no more than 3g increments.
A stick blender (or blender of some sort) is essential and a thermometer is invaluable for making these recipes.
60 drops = 1 tsp = 5ml
3 tsp = 1T
2T = 1 fl oz = 30ml
215g = 1 cup oil
240g = 1 cup water
Our experiments so far have shown the following: Light lotion: water phase 80%; oil phase 16-18%; Emulsifier O 2-4%. Initially this is very milky but it firms up over 48 hours. Face cream: water phase 80%; oil phase 14%; Emulsifier O 6%. Body cream: water phase 75%; oil phase 15%; Emulsifier O 8%. Body cream or butter: water phase 60%; oil phase 34%; Emulsifier O 6%.
If a skincare recipe contains only oils, butters, waxes, essential oils or fragrant oils (this is called a balm), it will not require a preservative.
Vitamin E can be added to balms to delay rancidity.
If any water (extract, juice, glycerin, gel, etc) is used, the recipe will need an emulsifier to combine the oils and water. (This is a cream.) A preservative MUST MUST MUST be used or the cream will go mouldy within a few days.
Vitamin E will not preserve creams.