Measuring soap batch sizes

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Active Member
Oct 29, 2007
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Cary, NC
I have a question about batch sizes. I read in the forum where people talk about making a 4 pound batch of soap or a 2 pound batch of soap. Then I also read items, and ads for soap molds that mention sizes such as "just the right size for 40 ounces of oils".

When talking about the size of soap batches, is it the weight of all the ingredients or just the weight of the oils portion of the mix that people are talking about. Also when looking at molds, when they mention "can contain 40 ounces of oils" are they actually talking about the entire oil/liquid/lye mixture or strictly just the weight of the oils?
oils is just "oils" not total weight..

4lbs batch of soap (oils, and water combined) = 64 ozs
40ozs is a little under 3lbs of oils...

I think I am answering your question
I guess I am confused and maybe not asking the right thing.

I guess I am confused by why people refer to "30 ounces of oils" or "40 ounces of oils" or whatever the amount might be, when the size of the actual batch of soap could vary widely. Depending on how much liquid you use, how much lye is required, if you add fragrance oil or essential oils or other additives like salt, oatmeal, the size of the actual batch can vary quite a bit.

And how does one know that a mold that says it hold "30 ounces of oils" is the right size when one recipe will turn 30 ounces of oils into a batch of 40 ounces of soap and the next recipe will turn 30 ounces of oils into 46 ounces of soap.
The oils have different specific gravity weights, for example coconut oil is a lighter oil than say olive oil is. One cubif foot of coconut oil weighs less than one cubic foot of oilive oil. bBut, weight is weight in a recipe. :) All soap makers go by oils weights when talking. For example, my TOG 10" mold uses 32 ounces of oils, referred to as a "2 pound batch or recipe" even though the log will weigh about 48 ounces or so when you are ready to cut it into bars. I don't know who started the idea that a 2 pound recipe was "just" oils used, but I can understand why it is used since everyone uses different water rates, different additives, etc.

So if your mold says 30 ounces it means use 30 ounces when figuring the recipe in your favorite calculator!

Have fun is the main thing.... :)

Paul.... :) :wink:
My point exactly, Paul. So how do I know that all recipes that use 30 ounces of oils will fit in a mold that claims it fits a 30 ounce recipe? One recipe that uses 30 ounces of a heavy oil and 10 ounces of water and 4 ounces of lye might fit while another recipe that uses 30 ounces of a very light oil and 15 ounces of liquid and 2 ounces of fragrance and a few ounces of another additive will pour out over the top of the mold. Just doesn't make an sense to me why the weight of the entire recipe is not used since that would be a more exact measurement.