Water (and Water Discounts) in Handmade Soap

First off, let’s stop using the term “Water Discount”

I personally hate the term “water discount”  it’s so confusing! It’s basically saying “I used this percent or amount of water less than the recipe was written for”.

The confusing part is that not all recipes, or all calculators, use the same amount of water. So, when someone said they used a water discount, you have absolutely no idea how much water they used unless they first tell you how much water they were told to use! Or, maybe they were just talking about discounting from the default amount of water called for in a soap calculator. FYI: this default is usually a decent water amount for hot process.

So, who cares how much water some calculator, or some random soap recipe calls for? Not me, and you shouldn’t either.

Stop the water discount confusion now! 😂 Instead, let’s figure how much water you NEED to make soap, and how much water (or other liquid) you can add to your formulation while still ending up with a nice bar of soap.

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Here’s how water works in soap:

You need equal amounts of water and sodium hydroxide in order to dissolve your sodium hydroxide. Together they create a sodium hydroxide solution. Some call this a 50% solution (where 50% of the solution is NaOH). Some, like me, call it a 1:1 (one-to-one) solution. And FYI: You can’t use less water because the sodium hydroxide will not dissolve in less that it’s weight in water.

Once you have your 1:1 sodium hydroxide solution, you can add more liquid as desired for your recipe. Typically this additional liquid is calculated as a ratio based on your sodium hydroxide weight.

Here’s an example:

• If your recipe calls for 100 gr of NaOH, you need minimum of 100 gr water to suspend the NaOH into solution and use it to make soap.
• For various reasons you may or may not want to add more water, or fruit juice, or tea, or milk, or any other liquid you can think of.
• To calculate the amount of additional liquid we would use additional “parts” based on weight of your sodium hydroxide.

Let’s take that same recipe calling for 100g of NaOH and add some carrot juice in a 1:1:1 ratio (one part water, one part NaOH, one part juice):

• Measure out your 100gr of water (to dissolve your NaOH)
• Measure out your 100gr of NaOH and dissolve it in your water
• Measure out 100gr of carrot juice and add it to your oils.

Remember, the “carrot juice” could be water, or milk, or any other liquid you wanted to soap with. They key part is that we are consistently dissolving our NaOH in an equal part of WATER to create our NaOH solution which we use to saponify the oils.

Based on your soaping temperature, your oil formulation, and other factors, you may or may not want to add additional water above and beyond what is required to dissolve the sodium hydroxide. Additional water can effect the gel phase, could cause your soap to over heat, and will actually cause your soap to trace faster. All of those things can be desired or catastrophic events… depending on your soapy needs.

We cover this in more detail in The Ultimate Natural Soapmaking Course, as well as in this article all about adding food stuff (which is usually liquids!) to soap. Plus, here’s a fun demo I did showing how various water amounts affect trace with cold process soap.

Here’s some more great reading covering topics that effect the water in handmade soap:

• 7 Tips to Control Trace in Cold Process Soap Making
• Adding Food to Soap -a Guide for Soapmakers
• Why soap might still be soft after days in the mold.
• Why Did My Soap Crack? Understanding the Heat of Soap Making
• Understanding the Gel Phase of Cold Process Soap Making
• Controlling Soda Ash on Handmade Soap: Love it or Hate it (with 12 examples of soda ash on soap)

If you still have questions about water in soap, drop a comment below. And, you can always join the next Members Only Soapy Q+A session where we talk one on one about any soapy situation you want to talk about!