# Using IRFA percentages for fragrance oil

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#### maxine289

Supporting Member
My question is about the percentage of fragrance oil that can be used. I sometimes purchase fragrance oil from Lonestar Candle Making and their bottles have the IRFA categories listed, including Category 9 which is for soap. The usage rate is stated as a percentage. My question is, a percentage of what? The total weight of the batch, which would include water/liquid, lye and oils, or the total weight of oils in the recipe? As an example, if a fragrance oil said Category 9 usage was 11%, and I was making a batch that will weigh 46 oz. (total weight of liquid, oil and lye and include 32 oz. of oils), would the amount of fragrance oil I could use be 11% of 46 oz, which would be 5.06 oz, or 11% of the 32 oz. of oils, which would equal 3.5 oz? In reality I would not use that much fragrance oil (either 5.06 oz or 3.5 oz for a 2 lb. batch), but based on the stated Category 9 usage percentage, COULD I use those amounts safely? I generally use 1 oz. of fragrance oil per pound of oils. I'm just trying to understand how to calculate the fragrance oil based on the IRFA percentage.

#### CaraBou

Supporting Member
In my opinion it would be total batch weight because that's what would determine concentration of the fragrance oil in the finished soap. But many calcs just use oil weight, possibly in part because they don't track all of the additives (though they would know water since that's part of the calculations). Brambleberry's FO calc is one that does use total batch weight - though of course they only have their fragrances loaded.

#### Millie

##### Well-Known Member
It would be okay to calculate fragrance based on fully cured soap weight (I think DeeAnna has a tutorial on her website to figure out what that would be), but not based on raw batch weight. A great deal of water evaporates, and how much we use to begin with is based on personal soaping style - yikes. I prefer to go by oil weight. Even then, 11% seems like too much. One oz ppo as you mentioned seems reasonable when IFRA guidelines indicate that would be safe.

#### shunt2011

##### Moderator Emeritus
Supporting Member
And the usage rate listed is the max recommended. I generally use 6% of the oil weight (1 oz. PPO) unless it's a super strong scent then I use less. It totally depends on the fragrance/EO I'm using. I use mostly FO's and don't use many that carry extremely low usage rates. I try to avoid those.

#### DeeAnna

##### Well-Known Member
Huh. I thought I'd responded to this one yesterday, but my post is absent. I'll try again!

For lotions and other potions, you'd use the total batch weight to calculate the fragrance amount. For soap, I think most people calculate their fragrance amount using the total oil weight. I don't think there's any particular magic to that -- I think this method is used because other additives are based on the oil weight in the soap recipe. Why not be consistent and do the same for fragrance?

I don't use oil weight to calculate my fragrance weight -- I base my fragrance on 90% of the total batch weight from the recipe. I don't use 100% of the total batch weight, because that includes water that will evaporate from the soap during cure. I want my fragrance % to be correct for cured soap, not freshly made soap. A loss of 10% of the weight due to evaporation is pretty reasonable, so that's where I come up with using 90% of the batch weight.

Even if the IRFA max is higher, my rule of thumb nowadays is that I never use more than 5% to 6% max for any fragrance. Some might be plenty strong at a lower %. I know from experience that rates above that will increase the risk of the soap separating a bit in the mold and/or the fragrance weeping out of the soap during cure and storage. On top of that, I want my soap to be mostly soap ... not soap with a ridiculous % of non-soap additives.

If the scent isn't strong enough or lasting enough at 6%, then I look for another fragrance that works better -- I don't bother to keep fiddling with a scent that isn't good enough at a reasonable %.

#### IrishLass

Staff member
Moderator
If the scent isn't strong enough or lasting enough at 6%, then I look for another fragrance that works better -- I don't bother to keep fiddling with a scent that isn't good enough at a reasonable %.

I'm the same way-- 6% ppo (1oz ppo) is my personal maximum usage rate for FOs. If they aren't strong enough to stick around in my soap at that rate, I look for a different version of the FO that will.

Most of the FOs I use, though, are plenty strong and long-lasting enough at 4.69%/.75oz ppo (I very carefully vet them and weed out the weaklings). Some are even strong enough to be used at 3% (.5oz ppo) or even less.

FOs are the most expensive ingredient in my soap- so the least amount I can get away with using in my soap, all the better for my purse.

IrishLass

#### DeeAnna

##### Well-Known Member
I want to also add that if the max IRFA % is less than 6%, I'm leery of using that fragrance -- I would rather use a scent that has a higher margin of safety that is implied by a high IRFA %.

For example, I have Nature's Garden Black Raspberry Vanilla that has a Cat 9 IRFA of 3.5%. It's way plenty strong at 3.5% or less, but I'd rather not see the IRFA % that low given my druthers.

#### josianeg

##### Well-Known Member
Question: how is it possible for a class 5A (ex: body lotion) IFRA max % to be greater than that of a class 9 (soap)?

According to this quality and regulatory information sheet

the max usage rate for the NDA Neroli fragrance oil is 5.7% for class 5A products ans 2.5% for class 9 products.

I haven't soaped or made lotions in a while, so maybe there is an obvious explanation that I'm missing...?

#### DeeAnna

##### Well-Known Member
The difference between the categories seems to depend on whether the product is normally applied to normal, unbroken skin or whether it's applied to irritated skin (shaving) or sensitive skin (underarm, gentialia) or is an aerosol product (cat 9).

I have more thoughts here -- IFRA guidelines | Soapy Stuff -- but I do agree the differences sometimes seem arbitrary to me too.

#### lucycat

Supporting Member
I would like to get back to the original question. If I see an IFRA of 3.5% for bar soap, I am assuming that the calculation was a number given to each of the fragrance components then divided by a total; but what was the total?

Was it based on the weight of finished cured soap? Since IFRA isn't just for handmade products was the total used based on more commercial soap production methods of soap noodles? Is there any way to know?

#### Faubush Farms

##### Member
I read once that it was because soap comes in contact with our private bits, whereas lotion will not. This made sense to me, but there could obviously more to it than just that.

#### bwtapestry

Supporting Member
Isn’t percentage of fragrance based on a wash off product vs a leave on product?

#### TheGecko

##### Well-Known Member
I think it's based on Oil Weight, which would be logical due to water evaporation.

I have a bit of a love/hate relationship with the IFRA. On one hand I am in the business of making a product that people are going washing their man/lady bits with and would prefer not getting sued, but on the other I think it's racket...especially since their latest recommendations cut the usage rate of one of my top selling soaps by almost 75% (from 8% to 2.6%) which is a bunch of horse feathers as my Grandma was fond of saying. At that rate, I might as well not use it because you barely smell it when the soap is freshly cut and it's just brown soap at six months.

I test all my FOs at 1oz PPO (6.25%) which is pretty standard. Doesn't always mean that I use it as some scents can be pretty strong; my goal is to create a pleasant bathing experience, not chase people out of their bathrooms.

#### DeeAnna

##### Well-Known Member
@lucycat -- IFRA rates are based on the finished product weight -- the product the consumer actually receives.

IFRA recommendations are not based on oil weight. Even though I know this is how many handcrafted soap makers calculate fragrance -- basing it on just the weight of fats in the soap -- this basis makes no sense for any other product other than handcrafted soap.

@bwtapestry -- Leave on versus wash off doesn't matter. IFRA is based on various categories and each category may have leave on products AND wash off products in it. Read my article -- you'll see a listing of the various categories and examples of products in each one.

#### bwtapestry

Supporting Member
@lucycat -- IFRA rates are based on the finished product weight -- the product the consumer actually receives.

IFRA recommendations are not based on oil weight. Even though I know this is how many handcrafted soap makers calculate fragrance -- basing it on just the weight of fats in the soap -- this basis makes no sense for any other product other than handcrafted soap.

@bwtapestry -- Leave on versus wash off doesn't matter. IFRA is based on various categories and each category may have leave on products AND wash off products in it. Read my article -- you'll see a listing of the various categories and examples of products in each one.

#### TheGecko

##### Well-Known Member
I would like to get back to the original question. If I see an IFRA of 3.5% for bar soap, I am assuming that the calculation was a number given to each of the fragrance components then divided by a total; but what was the total?

Was it based on the weight of finished cured soap? Since IFRA isn't just for handmade products was the total used based on more commercial soap production methods of soap noodles? Is there any way to know?
Good luck figuring out their "IFRA/IOFI NCS Complex Ingredient Constituent Compendium formerly called the IFRA-IOFI NCS Matrix".

It has nothing to do with production methods...soap is soap. Doesn't matter if it is made via Hot Process, Cold Process or Continuous Process...doesn't matter if you take soap and shred it with a grater in your kitchen or turn it into a noodles in a factory...it's soap.

##### Well-Known Member
IFRA have begun separating out leave on from rinse off categories, the latest sheets have way more categories than before including .. socks and cell phone covers. (!?)

IMO they also need to separate out the in-bath categories as currently one could use a single bath bomb and get the same exposure as in all the baths it would take to use up a bar of soap, without violating IFRA guidelines.

If one has questions though, really please ask your supplier to double check. I've seen some mentioned here that surely look like typos and I'd rather inquire of the supplier and their preparer than guess.

#### DeeAnna

##### Well-Known Member
IFRA have begun separating out leave on from rinse off categories....

Thanks for explaining that, Paradisi. I stand corrected.

##### Well-Known Member
Thanks for explaining that, Paradisi. I stand corrected.
No need! They're an ever-moving target. Gone are the days of years between changes, or even yearly. It's a scramble now.

Add that to the reformulating going on and it's like trying to rake leaves in a windstorm to keep up.

#### lucycat

Supporting Member
@lucycat -- IFRA rates are based on the finished product weight -- the product the consumer actually receives.

IFRA recommendations are not based on oil weight. Even though I know this is how many handcrafted soap makers calculate fragrance -- basing it on just the weight of fats in the soap -- this basis makes no sense for any other product other than handcrafted soap.

@bwtapestry -- Leave on versus wash off doesn't matter. IFRA is based on various categories and each category may have leave on products AND wash off products in it. Read my article -- you'll see a listing of the various categories and examples of products in each one.
Thank you for the response,

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