ROE revisited

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Feb 25, 2019
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Goldsboro, North Carolina
I've read as many of the ROE posts here as I could find before prevailing upon your forbearance and I know this is going to sound like a grade school math story problem, but my calculating skills have not progressed much beyond 5th grade. So I need some help.

I have a 35-pound bucket of pre-mixed soaping oils (35 pounds=560 ounces=15875.73 grams) and a 2-ounce (56.69905 gram) bottle of Lotion Crafter's ROE with 7% Carnosic Acid. (Yes I plan to call them in the morning, but thought someone here might chime in before then.) Their Formulation guide says:
-add 0.2 - 0.5 grams of ROE per 1000 grams of soaping oils
-on the same formulation guide it also says the usage rate is 0.02-0.05%.

After doing the math for both methods several times, using the low end of the recommended range of 0.2 - 0.5 grams/1000 grams of oil, I came up with 3.948 grams of ROE to add to my bucket of pre-mixed oils. Using the 0.02% recommended usage rate for a 15875.73 gram bucket, I came up with 3.175 grams. Can anyone tell me if I calculated correctly and if so why they would differ so much? Also, since these amounts are so tiny, would it be possible to dilute the 2-ounce ROE bottle with a portion of my soaping oils in order to have a larger, more dilute ROE solution that would be easier to dose from? Thanks in advance. Kari


Grandmother & Soaper
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Apr 30, 2016
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Western Illinois, USA
Zany_in_CO mixes ROE in jojoba oil; she describes how she does it in this post: ROE and DOS

Regarding the math:
0.02% of oils and 0.2 grams per 1000 grams of oil should be the exact same measurement, shouldn't it? In fact it is if you use this calculator (I like to double check my math, too.)

As for usage rates, it depends on the application for which ROE is used. ROE is used in other things besides soap. (Here is a link to food applications and other usage rates, just as a matter of interest.)

For me, when I determine usage rate for soaping oils, I prefer to follow the recommendations for amounts that Kevin Dunn found effective in his research and DeeAnna's article on her classicbells ROE page. I find that more informative than the all the different vendor information, with all of them including either more or less and often confusing information.
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