One of the first tools one needs in making soap, if they deviate from a specific recipe or try to develop their own, is a lye calculator. Soap making requires a bit of precision, it is very important to use the right amount of lye and the amount of lye varies depending on the types and proportions of oils and fats that are used. Most people use a piece of software to do these calculations for them and help develop their recipes. You can tell it how much of various oils you want to use, what percentage superfat you want (the amount of excess fat you want unreacted when the lye is used up), and how much water (or other liquid) you want to use relative to the oils or the concentration of the lye, and it tells you exactly how much lye and liquid to use to achieve this.
In my experience, by far the most popular lye calculator is a web-based app called
SoapCalc. People frequently screenshot their recipes in SoapCalc to request advice. Most new soapers are immediately directed to this resource. I initially developed my recipes in SoapCalc as well. But I soon began to look for a free software option. I was particularly interested in the idea of a Linux-compatible desktop application, but I found another web-based application that was open source,
Soapee. I was intrigued and wanted to know how the two compared. But most people seemed to have never heard of it and nobody could offer much of a comparison. So I dug in and did some research myself. I shared my findings with a
Soap Making group on Facebook and asked for input. So what I am sharing here is an updated version of what I shared there.
Layout and design
SoapCalc is more rigid and compact. Soapee
has a newer, more fluid design, but doesn’t fit as much information in
the same space. SoapCalc has sponsor ads on both sides while Soapee just
kind of fills the screen.
Lye options
Both offer options
for NaOH or KOH. SoapCalc offers a check box for KOH that is 90% purity
(although it does not make it clear what it assumes if this box is not
checked). Soapee allows you to specify the percentage purity of KOH and
also has a dual lye feature to use any proportion of NaOH and KOH. This is commonly used to make shave soaps that are soft and whip up a rich, creamy lather. Smaller amounts of KOH are used by some soapers to adjust the lather of their general purpose soap bars as well.
Soapee also helps the beginner by listing NaOH as being for solid soap
and KOH for liquid.
Measurement options
Both offer similar
units of measure. Soapee offers kilograms, in addition to grams, but
that seems trivial. Soapee also offers percentage for fragrance oils, in
addition to g/kg, but that also seems trivial. Soapee has an option to
specify total weight of oils and water, rather than basing the recipe on
oil weight. Both support specifying water as a percent of oils, lye
concentration, or water to lye ratio. Soapee also has an option to
specify a water discount, but I don’t really understand the point of
this and haven’t found anyone who could explain why you would not just adjust your water amount to begin with. Soapee also has an option to superfat after cook, for hot process
soapers, in which case it calculates a 0% superfat recipe and tells you
how much oil to add at the end for your superfat. You don’t specify what oil to use for your superfat because it does not matter to the lye calculations since won’t be reacting with the lye anyway (but you can, and should, include this in your notes when you save the recipe).
Oils and properties
Soapee has a longer list of fats and oils, but both have all of the
fats and oils I have commonly seen used, plus plenty of exotic options.
But I guess if you don’t find an oil you want to use in SoapCalc, you
may find it in Soapee. They both show properties and fatty acid profiles
for individual oils and the recipe as a whole. They both calculate properties in the same way. Soapee only lists fatty acids
that are present in the recipe, while SoapCalc always presents the same
list and those that are absent will show 0. The “creamy” property in SoapCalc is called “stable” in Soapee. Soapee has a “longevity”
property that is not in SoapCalc. (Stable/creamy is the total of palmitic, stearic, and ricinoleic acids; longevity is palmitic and stearic acids.)
Saving recipes
SoapCalc allows
you to save a limited number of recipes as cookies. They can only be
referenced by number and are gone when your cookies are cleared. Soapee
allows you to create a login, save recipes long-term, and reference them
by name.
Calculating Recipes
SoapCalc requires you to
click one button to calculate the recipe and another to view/print it
(which opens the calculated recipe in a new tab or window). Soapee
calculates the recipe automatically and displays it below the calculator
as you tweak it.
Names and notes
SoapCalc allows you to
name a recipe and include additives and notes on the recipe view/print
page. These are lost when the tab or window is closed. Soapee allows you
to name the recipe and include a description and notes/method, which
can include rich text and pictures. These are saved with the recipe.
Conclusion
Overall, I have found Soapee to be the superior app, both for beginners and advanced soapers, in spite of being lesser known. I think that SoapCalc is more widely known in part because it has been around for a long time. But my personal recommendation would be to give Soapee a try.