What is the Safe Amount of Essential Oils?
A while back I was at a local market and was checking out one of the vendors handmade soaps. I picked up a peppermint scent and brought it to my nose. Wow was it strong! I asked the vendor if they had any tricks to retaining the smell in their soap and she said, oh we just keep putting more in until it smells strong enough! I cringed. This is a big no-no folks! According to the IFRA organization, fragrance and essential oil usage should be based off the weight of the rest of your base oils. For cold process soap, essential oils will make up anywhere between 1-5% of your recipe. Everything in soap making is highly calculated. Nothing is just thrown in until deemed enough. The only exception might be additives such as colorant, powders, etc.
The International Fragrance Association's (IFRA) mission is to promote the safe use of fragrance for everyone’s enjoyment. There are also online calculators such as https://www.eocalc.com that aim to do the same. The IFRA updates these standards periodically. It is important as a crafter to stay up to date on these changes and continue to monitor the usage of, any fragrance and oil compounds you use for your formulas.
Next time you pick up a bar of soap at your local farmer's market, ask the soaper what percentage of EO's they use! They may be caught off guard but an experienced soaper will know exactly what you are asking and should be able to provide you with that information.