Recipe or Formula?

How do you decipher between a recipe or formula? Everyone loves sharing a recipe, but unfortunately in skincare this could be an error. Recipes are measured in weight, cups, tablespoons, teaspoons or drops. However, this is not a skincare formula. A formula is carefully calculated and measured in weight, and yes, even liquids including the minute amounts of essential oils. Not many would give away a formula that has been written by a natural cosmetic formulator. I have come across many recipes both on the internet and in books or other reading material, which surprised me with the amount of misguidance given.
A formula is carefully calculated and ingredients are checked to comply with international regulated standards. Because essential oils are potent and concentrated, complying with regulators is a necessity. Oils may have contradictions or allergens that need to be taken into account when formulating.
Anhydrous products are products that are formulated using oils, butters or waxes. Products that contain water must have a preservative included as harmful bacteria may grow with the inclusion of water. Some recipes indicate vitamins or certain essential oils (e.g. Rosemary essential oil) are the preserving system, but these do not function as preservatives. They are typically included to assist in lengthening the shelf life of the carrier oil as some oils can go rancid very quickly.