Here's a post I made at the "liquidsoapers: discussion group at Yahoo in response to a soapmaker's question there:
So, when using this calculator, should I put in zero for superfatting if I want to react all KOH but not have any unreacted oils? I'm assuming yes, but just checking.
To clarify:
Yes, that is exactly true. I programmed and tested our SBM soap calculator to create potassium hydroxide (liquid) soaps that are as close as possible to 'neutral' pH values for LS's when the initial "superfat" input is set at zero.
To be totally precise, the result is in fact biased a very, very small amount toward providing a minuscule excess amount of lye, resulting in a finished product pH of approximately 9.5 to 10. This is to provide the smallest margin possible with the least process to avoid an excess fatty acid situation that could result in cloudiness in the finished soap.
The final produced soap should be clear and quite usable without any further 'neutralization' with borax.
Potassium (liquid) soaps made with just single oils can actually be 'neutralized' to lower pH values in varying degrees according to which oils are used. Coconut-only oil liquid soap can be very carefully 'neutralized' to as low as 8.5-9 pH, but it has to be done very, very carefully using an accurate electronic pH meter - a process that is way too 'persnickety' for the average soapmaker. LS made with other oils can also very carefully be nudged to lower pH values, but to a lesser extent than coconut oil LS. If you want to make LS with the lowest possible pH value, use our 'advanced' calculator with its recommended methods.
Our SBM 'regular' calculator and our 'advanced' SBM calculator versions use the same calculations to create potassium hydroxide liquid soaps with the Failor water-only process.
Our 'advanced' SBM calculator also provides a guided method to produce liquid soaps using the water-only Failor method OR our own water & alcohol method.
The 'advanced' calculator inputs automatically default to recommended values when input fields are left blank (ie: superfat defaults to zero) OR users can enter their own preferred values to override the default values.
The 'advanced' calculator also specifies a suggested process involving measuring the batch weight, etc to result in a 'standard' 50% soap-content in every finished batch of liquid soap base. This allows automatic calculation of water additions to achieve chosen final product dilution percentages and allows calculation of precise amounts of borax (powder or solution) to 'nudge' the final pH to the lowest value for maximum mildness. This suggested method is admittedly 'picky' (and a bit of a bother), but it allows production of multiple batches with exactly the same results every time without the guesswork of trying to manually adjust the final soap to the dilution and maximum mildness you want.
For adventurous experimenters, our 'advanced' SBM calculator also allows the use of mixed potassium and sodium hydroxides in liquid soap production. Liquid soaps can be 'thickened' by using a percentage of sodium hydroxide along with the usual potassium hydroxide. The math involved in figuring out how to use a specified percentage (by weight) of sodium hydroxide is a very complicated project (read that as "a ridiculously complicated PITA..."), but those calculations are built into the calculator, so you can accurately rely on our SBM advanced calculator to do it for you.
Our SBM calculator results and methods have been tested and verified with multiple batches using various oils from the soapmaking supplies that we provide at the SBM website using a sensitive electronic pH meter. Other oils from other sources may vary in SAP values a bit, so doing a test batch is suggested before committing to large and multiple batches for production if you are getting your oils from other sources.
The bottom line is this:
If you are a casual soapmaker wanting to reliably make liquid soaps with minimal hassle, use our 'standard' SBM soap calculator and don't worry about final 'neutralization' adjustments.
If you are a more advanced soapmaker wanting to reliably make multiple batches of the same liquid soap formulas with reproducibly same dilutions and maximum adjusted mildness, use our 'advanced' SBM calculator. Use it also if you want to use an easy alternative water-and-alcohol method or if you want to experiment with mixed potassium & sodium hydroxides.
[The advanced calculator will also work for those who wish to experiment with making cream soaps. Commonly accepted input values are set as override-able default values for cream soaps, but do realize that there is a wider variation of what is considered correct in making cream soaps than for making liquid soaps. One needs to be adventurous to venture into making cream soaps.]
This is a lot of 'soap geekiness', but I do hope it helps to clarify any questions one might have about our SBM soap calculators.
Thanks for the 'heads up' re the non-operative 'help' button links.
One of the downsides of having created a multi-faceted website like this one and being 'chief cook & bottle washer' for this and everything else is that I sometimes don't catch it when some links or other function goes awry and stops working (This can happen when I upgrade various parts of the website's 'backdoor' processes).
I really do appreciate it when someone points it out to me. Of course I do give myself a 'dope slap' later for not having caught it first! (In a dark room when no one is looking - It's a 'guy thing')
I just fixed the upload-your-image function for contributors' use to "Show Your Stuff" in new Topics posted at our forums. I am now posting specific directions for this and will turn to fixing the 'help' button links at the SBM calculator tomorrow.
Steve M.
Summer Bee Meadow
Site Administrator