Many people use use the default "water as % of oils" method to calculate the amount of water for their soap recipes. In my article "Full water and other drippy myths", I explain this method is not the best to use if you want consistent results in your soap making.
So when and why did "water as % of oils" become the default way to calculate the amount of water? It appears that calculating the water based on the amount of fats in the recipe is a relatively recent invention, compared to calculating water based on the amount of alkali in the recipe.
Booklets and pamphlets for home soap making dating to the early to mid 1900s do not explain how to calculate soap recipes. They just provide pre-made recipes.
When I checked soap making books published in the 1990s and 2000s, nearly all the authors based the water weight on the alkali weight, not on the weight of fat.
I have had no luck finding who first used the concept of "water as % of oils." I strongly suspect the "water as % of oils" method was popularized by one of the early online soap recipe calculators. Soapcalc is the most likely possibility, in my opinion.
Soap recipe calculators first appeared on the internet in the early 2000s. I checked the Wayback Machine for archived copies of the SummerBeeMeadow and SoapCalc recipe calculators, the oldest online calcs I know of.
The archves show the basic SummerBeeMeadow (SBM) recipe calculator (6) was first available on the company's website in mid 2002. The advanced SBM calc was added in early 2010.
I cannot tell if the very earliest versions of the SBM calc used the "38% water as % of fats" rule, because websites archived on the Wayback Machine cannot do calculations and queries. When I first wrote this article, however, the basic and advanced SBM calcs were still active and available for use, so I tested both. Neither version permitted the user to change the the water content, but it appeared in my testing that both calculated the water weight based on a 30% lye concentration (2.3:1 water:lye ratio.)
The popular SoapCalc (7) was first archived on the Wayback Machine in 2009, so I presume this is when SoapCalc first became available on the internet. Even in its early incarnation, SoapCalc allowed the user to define the water content based on "water as % of oils" as well as lye concentration and water:lye ratio. The default setting for SoapCalc was and still is "38% water as % of oils."
Calculating water based on the alkali weight has been in use at least as long -- and probably longer -- than the "water as % of oils" method.
In 1995, Susan Miller Cavitch published The Natural Soap Book. She does not clearly explain how to calculate the amount of water, but she does say the water content should be based on the amount of alkali:
"...Too little water won't bring the [sodium hydroxide] into solution, causing the final soaps to be brittle and dry. Too much water will add unnecessary moisture to the soaps, making them less lasting and too soft. ... Keep in mind that a formula is somewhat flexible with respect to the amount of water required to dissolve an amount of sodium hydroxide; acceptable amounts need not be exact, but rather fall within a range...." (4)
This book has no information about internet resources for soap making except for the website addresses of some suppliers.
In her 1997 book The Soapmaker's Companion, Cavitch provided more detailed advice for calculating the water amount based on the alkali weight:
"...Most turn-of-the-century soap formulas use a 30 percent lye solution. Though the soapmaking process was very different then, 30 percent is still a good starting point.... First you calculate the amount of sodium hydroxide that you need, which depends entirely upon the amount of fats and oils and their SAP values.... Then you calculate the amount of water by dividing the weight of NaOH by three-tenths (.3). (9)
Dividing the NaOH weight by 0.3 is equivalent to a lye concentration of 23% (water:lye ratio of 3.35.) That would be fine for hot process (HP) soap making, but is more water than is ideal for cold process (CP) soap making.
Companion, published just two years after The Natural Soap Book, is very much a child of the internet era. It contains an entire chapter about internet soap making forums, supplier websites, and online chat groups.
Companion offers no information about online soap recipe calculators, however, which implies online calcs were not available in the late 1990s. (10) This is consistent with the information gleaned from the Wayback Machine about the SoapCalc and SBM calculators, both of which debuted on the internet a few years after Companion was published.
In her book Making Transparent Soap, published in 2000, Catherine Failor explains how to calculate the amount of water based on the weight of alkali. She recommended using a 32.5% lye concentration (2.08 water:lye ratio) in her book:
"...all the recipes in this book have been calculated on the basis of a fairly standard-strength lye solution: 32.5 percent caustic soda to 67.5 percent water. Dividing 67.5 by 32.5 equals 2.08. That’s the constant you’ll use for the [caustic] soda/water solutions. If you multiply 13 ounces of dry caustic soda by 2.08, you’ll need 27 ounces of water (or a total of 40 ounces lye solution)...." (8)
Making Transparent Soap has a long list of suppliers including websites, but makes no mention of soap recipe calculators.
In 2007, Anne L. Watson published Smart Soapmaking. Although the book gives clear, common sense instructions and recipes for making soap, the book is vague about how to calculate the water weight for a soap recipe.
Watson does list five online recipe calculators in this book -- SoapCalc, Bramble Berry, Cranberry Lane, Majestic Mountain Sage, and Pine Meadows -- which shows there were a variety of online calcs available in the mid-2000s. (10) All of these calculators are still available for use as of the time of this writing.
Elizabeth Letcavage and Patsy Buck originally published Basic Soapmaking in 2009. Like Cavitch and Failor, these authors also advised soap makers to calculate the water based on the alkali weight.
"...multiply the weight of the lye by 2.5 to get the weight of water to be used. This is the mathematical formula: Lye x 2.5 = H2O. ... The 2.5 value is somewhat flexible, however. You may choose to use more or less, but remember that you must have enough water to dissolve the lye. Do not go below a multiplication factor of 2.0..." (5)
The water:lye ratio of 2.5 is the same as a lye concentration of about 28%. The water:lye ratio of 2.0 is a lye concentration of about 33%.
Although Basic Soapmaking includes a list of suppliers complete with website addresses, the book does not mention any online recipe calculators.
The Soap Making Forum got started in late 2006 and the first question about "water discount" was asked in March, 2007 (https://www.soapmakingforum.com/threads/water-discounting-question.459/)
Discussions on this topic since the beginning clearly show the water-based-on-alkali method was often used by soapmakers to determine the water content in their recipes. Many of these soapmakers are as skeptical as I am about the usefulness of "full water" and "water discount" as well as "water as % of oils" --
A comment in a 2008 thread: "...Most soapers consider a 33% lye solution a discount...." https://www.soapmakingforum.com/threads/water-discount.2614/
A comment from a 2009 thread: "...I like talking in terms of lye solutions over the term 'water discount' because water discounts are quite a hazy, inconsistent animal in comparison to lye solutions for me...." https://www.soapmakingforum.com/threads/water-discounts.9501/
A second poster in this same thread explained, "...saying something like "I use a 34% water discount" could be interpreted several different ways...."
A comment from another 2009 thread: "...I recommended to ... that she try not using the default - Water as a % of Oils - on SoapCalc, but rather try a batch using a Lye Concentration of 33%...." https://www.soapmakingforum.com/threads/is-there-any-adverse-effect-in-water-discounting.13152/
And here is a gem from a third 2009 thread: "...'Full water' is a nonsense term - it simply means using the default amount of water recommended by the calculator, and different calculators recommend different amounts. 'Discount' is the other nonsense term - because it means discounting (as in reducing) the amount of water, and the % discount is impossible to know unless you know the starting point, but since different calculators have different default amounts..." https://www.soapmakingforum.com/threads/water-discount-table-for-c-p-soap.11193/
References
(4) Cavitch, S M. The Natural Soap Book. Storey Publishing. 1995. pg 53-54.
(5) Letcavage, E, and Buck, P. Basic Soapmaking. Stackpole Publishing. 2009. pg 98-101 and 126.
(6) SummberBeeMeadow soap recipe calculator. Now defunct, this calc was available from 2017 through 2022 at this URL: https://sbmcrafters.com/content/soapmaking-calculator-and-recipe-resizer. The calc was active from 2001 through 2017 at this URL: http://www.summerbeemeadow.com/content/lye-calculator-and-recipe-resizer
(7) SoapCalc soap recipe calculator. This calc has been active from 2009 to the current day at this URL: http://soapcalc.net/calc/SoapCalcWP.asp
(8) Failor, Catherine. Making Transparent Soap: The art of crafting, molding, scenting & coloring. Storey Publishing. 2000. pg 75 and 178-190.
(9) Cavitch, S M. The Soapmaker's Companion. Storey Publilshing. 1997. pg 240-243 and 326-330.
(10) Watson, Anne L. Smart Soapmaking. Shepherd Publications. 2007. pg 63 and 110.
Copyright © 2002-2025 - All rights reserved by Classic Bells Ltd.
Template by OS-templates.com
