Do oils evaporate while warm on stove?

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lindsycarter

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So I had a big soap making weekend. I decided to do my first master batch of oils since I was making around 10lbs of soap of various scents and additives. I measured all the oils out before adding to the main pot on double boiler, measured them again right before actually adding to the pot. Once all melted and the first lye solution mixed and cooling I measured out my first amount of oil needed. Once I got down to the very last batch, I was nearly 13 ounces short on oils so, based on my percentages I had to run a lye calculator again in order not to waste the oils but my last batch ended up very small. Is there a limit to how much time is recommended for oils being warmed? I didn't think they would evaporate so much (or at all).
 

DeeAnna

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No, they should not evaporate. The molecules of fat are very large and they do not want to turn into a gas easily.

A loss of about 10% (13 ounces out of 160 ounces) is pretty high. But I'm betting on measurement error. Here's what I'm wondering -- Does your scale weigh to whole ounces or 1/10th of an ounce? If it weighs to whole ounces, there's most of your problem. There can be around a 0.5 ounce error, over- or under-weight, when using a scale with that kind of accuracy. And since we tend to over-pour, the likelihood is you were pouring a little bit too much for every batch. After making however many separate pours that you made, the extra little bit from every pour added up to a lot.

Just a guess....
 

shunt2011

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I agree with DeeAnna that it's likely a weighing error. I master batch my oils all the time 8-10 5lb batches and don't have that kind of error. I measure in grams always, and if anything I'm usually over a bit by the last batch due to a bit of overpour.
 

dixiedragon

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No, they should not evaporate. The molecules of fat are very large and they do not want to turn into a gas easily.

A loss of about 10% (13 ounces out of 160 ounces) is pretty high. But I'm betting on measurement error. Here's what I'm wondering -- Does your scale weigh to whole ounces or 1/10th of an ounce? If it weighs to whole ounces, there's most of your problem. There can be around a 0.5 ounce error, over- or under-weight, when using a scale with that kind of accuracy. And since we tend to over-pour, the likelihood is you were pouring a little bit too much for every batch. After making however many separate pours that you made, the extra little bit from every pour added up to a lot.

Just a guess....
But wouldn't the OP have ended up with MORE oil, not less, in this scenario?
 

DeeAnna

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No, she would be short at the end.

Say I make up a master batch of 50 oz.
I want to use this oil to make 5 batches that contain 10 oz of oil for each batch.
I unintentionally overpour each batch of oils by 0.5 oz -- in other words, I pour 10.5 oz per batch, not 10 oz.

After 4 batches, the total accumulated shortage of oil would be (4 batches) X (0.5 oz too much oil per batch) = 2 oz.
So my last portion of oil would weigh only 10 - 2 = 8 oz.
The error would be 4 / 50 X 100% = 8%.
 

lindsycarter

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I specifically set my recipe to weigh in ounces by 1/10 oz since my scale is only accurate to that degree. I measured several times since this was my first time master batching the oils. So I am nearly positive that everything was weighed accurately (several times). I figured the recipes the day before, recalculated through the lye calculator then reweighed oils before adding them. Still don't know what I did wrong. Thanks for all the suggestions!
 

DeeAnna

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For that much error, there's something not right. I'd have to be there and see what you're doing to help you further. Maybe others will have some suggestions.
 

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