# Help with math, adding FO's to diluted LS

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#### nsmar4211

##### Well-Known Member
After finally getting a decent thickness to my LS, I've started down the road of adding FO's.

I have my base unscented soap in 2oz bottles. I ended up diluting at 2x, so, 2 oz of paste required 4oz of water. That was split into three bottles. To each bottle I started with 10 drops of my desired FO. One FO (dragon's blood) was fine at 10 drops so I decided to try and figure out what percent that was....and my brain is frozen.

From what I can tell, 10 drops is 0.022 ounces. So, if I went by finished dilution rate, that's 1.1% (2oz divided by .022 ounces times 100 for percent), right on the money. BUT, the FO rates are per pound of oils...so, since I had to dilute with 2x the paste, I'm really dealing with 1/3-1/4 of that in oils...so it's really .3% -.25%???

So the other two that are not happy with 20 drops may not be that far off and the 10 drop one is just realllly strong?

Help.......

I assume you're using fl oz and not a weight measurement when you say 10 drops is .022 oz? What are the recommended usage rates for your fo? When I do LS, I use the whole product weight to figure my fo usage. LS is different that bar soap because it contains a lot more water and it doesn't evaporate like it does in bar soap. So your original 1.1% figure is correct in that situation. A lot of people use 1 oz ppo in bar soap, and that translates to .06% So it may be simply a matter of 1 fo having a stronger scent, and the other 2 a lighter scent. Find out what the recommended usage rates are for YOUR fo's and then scent to what pleases YOUR nose.
Basically, your math's are fine. You just have to relax on the figures a bit and make a soap that smells as lovely as it works

Yes, definitely use the diluted soap weight to calculate your scent weight. There's no point in worrying about scenting a diluted soap based on the starting oil weight.

Start with 0.5% to 1% of scent by weight (0.5 to 1 gram of scent per 100 grams of diluted soap). You can always go up in dosage so 0.5% is a good place to start if you're not confident about the strength of the scent. Don't do drops -- they're really not too handy unless scenting a tiny batch of product and your scale won't weigh that low.

Tip: If you use two fragrances to scent your soap, the 0.5% to 1% guideline is for the TOTAL amount of scent, not for each individual fragrance.

Another tip: Can your scale be set to give you the weight in grams? That's going to give you numbers that are easier to remember and work with.

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Ok so the brain isn't broken! Thank you for the replies! I will just work with the diluted number...much easier... and yes, for the drop amount I used Google and that's fluid ounces.

I'm using such small amounts because I'm testing the reaction of the LS to the FO's I have (I'm looking at you Lavender....I now have gel?!). Once I figure out what will and won't cause weirdness, on to larger quantities!

My scale does do grams, but the FO amounts are so small it won't go that far so for now drops it is to give me a general idea on how much to add. Great reminder that I should try grams for the next dilution (which will be 8oz vs 2oz quantites).

One issue is my Peppermint FO is now up to 4% based on diluted weight...and I don't smell mint. That may have to go to my work with me to see if my nose has just quit smelling mint. The rest are nowhere near their recommended amounts so I'm safe

I'm using such small amounts because I'm testing the reaction of the LS to the FO's I have (I'm looking at you Lavender....I now have gel?!). Once I figure out what will and won't cause weirdness, on to larger quantities!

Blue Sugar did that to mine! Or at least I thought it did. Now I'm pretty sure I didn't have my soap quite diluted enough and the PS80 I added with it was just enough to thicken it back up. But the Blue Sugar isn't completely off the hook yet lol

Blue Sugar did that to mine! Or at least I thought it did. Now I'm pretty sure I didn't have my soap quite diluted enough and the PS80 I added with it was just enough to thicken it back up. But the Blue Sugar isn't completely off the hook yet lol

I used an ocean type scent from candle cocoon in LS and got Dippity Do.

I used an ocean type scent from candle cocoon in LS and got Dippity Do.

I haven't seen Dippty Do in years! I remember it being green though.

Dippty Do came in different colors depending on strength of the gel if I remember correctly. but I do not always remember correctly...

Just an FYI: I decided after seeing your thread to weigh the 60 or so FOs that I aliquoted today in small tubes to be used for 1 oz testers. I pipeted exactly 1.5 ml which translates into about 30 drops. For a reference, 1.5ml of water weighs exactly 1.5g. I expected FOs to be lighter than water. To my surprise, most of them weren't. The majority fell between 1.4g and 1.6g. Only one citrusy FO weighed 1.35g. Some of the vanilla FOs weighed 1.7 to 1.8g. This is my long way of telling you that you could ignore the weight and use volume instead. You can just use measuring spoons.

Soapmaker: Wow, thanks for that information! Great to know .

Just an FYI: I decided after seeing your thread to weigh the 60 or so FOs that I aliquoted today in small tubes to be used for 1 oz testers. I pipeted exactly 1.5 ml which translates into about 30 drops. For a reference, 1.5ml of water weighs exactly 1.5g. I expected FOs to be lighter than water. To my surprise, most of them weren't. The majority fell between 1.4g and 1.6g. Only one citrusy FO weighed 1.35g. Some of the vanilla FOs weighed 1.7 to 1.8g. This is my long way of telling you that you could ignore the weight and use volume instead. You can just use measuring spoons.

But when a scent states "usage rate =x%" to what does it refer? X% by weight or by volume?

THAT should be the decider in whether or not someone uses weight or volume to measure their scents

But when a scent states "usage rate =x%" to what does it refer? X% by weight or by volume?

THAT should be the decider in whether or not someone uses weight or volume to measure their scents

You can measure by weight or volume as it suits your purposes and get sufficiently consistent results. Conforming to a supplier guideline really strikes me as being of minimal importance.

Maybe it's because I originally come from the candlemaking side where nobody would take that seriously. In that realm, the only meaningful decision about usage rate would come from testing in a particular application. There are too many technical factors.

Even if I stipulate that FO performance in soap is a simpler and more predictable matter, it's still the furthest thing from an exact science. Most suppliers can't even demystify colorant usage rates for their customers, so it's hard to believe they do such a brilliant and conscientious job with a more difficult subject like fragrance.

I think maybe the main point of soapmaker's post is that there actually isn't much difference between weight and volume when the density of a liquid approximates that of water. 1 fl oz of water weighs a shade over an ounce -- maybe an extra .05 g that most people can't even accurately measure. Variations might throw you off by a few grams.

TOMH said it much better than I did. As usual, I was as clear as mud.

TEG: the usage rate is by weight not volume. I spent some time reading some of the information on the IFRA website. I think this booklet is worth reading: http://www.ifraorg.org/Upload/Downl...A Information booklet V7.1 (July 9, 2015).pdf

They have something called maximum pragmatic level which restricts any one chemical in an FO to no more than 5% regardless of the overall usage rate. They specifically target methyl eugenol, estragole and citral which are components of most essential oils. This document pretty much guaranteed that I would be purging most EO from my own collection. Usage rates in parts per million and 0.01% is too low for comfort.

FWIW, I like to use FOs at half of the maximum usage rate or 5% whichever is lower. It gives an additional margin of error beyond what is built into the IFRA.

Nsmar, I didn't mean to derail this thread.

Soooo according to that booklet, there are a ton of EO's not safe...wow...

Another source said: Commonly used oils with more than 0.1% of methyl eugenol include calamus, rosewood, elemi, ylang ylang, cymbopogon, star anise, lovage, verbena, nutmeg, basil, pimento, bay leaf, rose and clove.

....which, when combined with the booklet's info, means usage rates would be so low to be almost unusable...fascinating!

*****
Some of my FO's have usage rates of 20%....I can't even imagine putting that much into a soap! I like the "half or 5%" idea.... I may steal that.

Soooo according to that booklet, there are a ton of EO's not safe...wow...

Another source said: Commonly used oils with more than 0.1% of methyl eugenol include calamus, rosewood, elemi, ylang ylang, cymbopogon, star anise, lovage, verbena, nutmeg, basil, pimento, bay leaf, rose and clove.

....which, when combined with the booklet's info, means usage rates would be so low to be almost unusable...fascinating!

Some of those might be pretty usable. For instance, if you don't have an analysis of your ylang ylang you have to assume 0.5% eugenol according to IFRA, so that's the worst case scenario. If the limit is 0.01% eugenol, you can use 2% ylang ylang by final product weight, or about 2.7% relative to oils -- almost 1/2 oz ppo. With ylang ylang that should be enough to impart a pretty good stink. Probably it's just part of a blend. If you have an analysis of the lot your EO is from, you might be able to use much more.

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