An IFRA is a specific document supplied by a fragrance manufacturer, that states the safe percentages that the fragrance can be used at in different products.
Typically there are around 11 categories or classes in an IFRA, with most consumer products slotting into at least one IFRA category.
Understanding percentages of an IFRA
Each IFRA for each different fragrance, will show a 'level of use' percentage. It is this percentage that causes a lot of confusion.
In a nut shell, the 'level of use' percentage means 'how much of that fragrance you can safely use in a product'. It DOES NOT then also equal how much you can use and that is where the confusion lies.
Some fragrances, for some categories, can be listed as 100%. This technically means the fragrance is extremely skin safe and could be classed as a finished product in itself.
You must, however, take into account, your maximum loading that your product you are creating, can hold.
For example: Angelic whispers lists 'level of use' for candles as 100% This means its extremely safe to use in candles. HOWEVER, the maximum amount of fragrance most soy waxes can handle is between 10 and 12%. You cannot add, say 25% of Angelic Whispers to your candle as it simply will not burn and will leech out of the wax.
Category 3C states the level of use for body creams and lotions is safe up to 10.71% Great! However, the maximum amount of fragrance body creams and lotions can hold before they separate like curdled milk, is around 4-5%.
In summary, the IFRA percentages tell you how much of a fragrance you can use in your finished cosmetic/air freshener products safely. It is then up to you to understand how much 'loading' or how much fragrance, your product can hold, before it falls apart, seizes or is completely wasted.