Terms & Definitions
Before you begin to make soap you will need to understand some of the terms that are used in soap making, for example, do you know what Trace is? Or maybe SAP? If not do not worry because, when you are done reading this post you should be able to explain what those two terms mean plus many more that are used in soap making.
What is lye? You probably have heard of lye, lye is a caustic ingredient that when mixed with oils and fats make a new substance called soap.
There are several kinds of lye, the chemical name for lye always has the main element and hydroxide in it. In soap making we use two kinds of lye their chemical names are Sodium Hydroxide and Potassium Hydroxide.
- Sodium Hydroxide – (NaOH) Is used to make solid soap
- Potassium Hydroxide – (KOH) Is used to make liquid soap
When you mix the two together, along with the right combination of oils and fats you can create a cream soap.
Grades of Lye
In addition to being different kinds of lye there are also different grades of lye, in soap making we will only be concerned with two grades.
Technical Grade – Most soap makers use technical grade lye, it is less than pure and is cheaper than food grade.
Food Grade – Is used to make things like pretzels, olives or bagels, some soap makers prefer to use food grade to bring a higher quality to their soap making. Food grade lye is more expensive than technical grade lye.
While I have used both grades I prefer to use food grade, it is said to be stronger and more predictable, and with less impurities.
Forms of Lye
Lye comes in both dry and liquid forms, in soap making dry is usually the preferred form, and the form most soap makers use. Dry lye in my opinion is safer to store than liquid lye. Dry lye is hydrated before use and until it is mixed with a liquid is inactive. Storing active liquid lye is a safety hazard in a home environment.
Most people know what vinegar is and probably use it, but what does vinegar have to do with soap making? Vinegar is an acid, Lye is a alkaline or base and the opposite of an acid. Vinegar is used in soap making to neutralize lye spills and accidents and while not used in the recipe is a very important part of keeping you safe.
Oils, Fats & Butters
What do you think of when you hear the words oil or fat? In soap making the most important thing to know about Oils & Fats, is one is solid and the other is liquid at room temperature.
- Oils – Are liquid at room temperature, the most popular oil used in soap making is olive oil, but any liquid oil can be used. Oils do not need to be melted before using in soap making.
- Fats – Are solid at room temperature, the most popular fats used in soap making are coconut and palm oil, and while they are called an oils they are fats at room temperature and need to be melted before using to make soap.
- Butters – Are fats that are solid at room temperature, they include Shea & Cocoa Butter.
Saponification is the process that turns oils, fats and lye into soap.
SAP or Saponification Number
The acronym or word SAP is used in soap making and is a shortened form of Saponification, usually it is used when talking about what is needed to turn oils, fats and lye into soap. Each and every oil and fat has its own requirement of lye to become soap, and that requirement is its SAP value or Saponification number.
The saponification number is the number of milligrams of lye necessary to turn 1g of oil, fat or butter into soap. When creating a soap recipe we need to find the sap value or saponification number for each oil and fat we will be using then add them up to come to the total amount of lye that is needed.
If we were chemist we would use our knowledge of chemistry to determine SAP values for each oil or fat in our soap recipe. But because most soap makers are not chemists instead of making our own determination, we use industry recognized standards for SAP Values.
Places To Find Sap Values
There are many places online to find Sap Values, especially on soap making sites. Here is one I found after a quick search, From Nature With Love Saponification Chart. You can also find them in some soap making books.
But do you really need to do your own calculations? Many soap makers like doing their own math, but not me I would rather leave it up to the experts. You see some smart soap makers got together with smarter programmers and came up with a tool to do the calculations for us.
The “Lye Calculator”
The “Lye Calculator” is the tool that soap makers use to calculate the sap values and determine how much lye they need to make soap. It is such a useful tool that I do not know many soap makers who still do their own math.
Online Lye Calculators
Lye Calculator Software
Superfatting is when you make soap with leftover oils, the leftover oils help make the soap less drying and more moisturizing. Remember when we talked about the SAP value or number, that number tells us how much lye to use to turn the oils and fats into soap? When we follow that equation we get a 0 percent super fat, leaving our soap without any leftover oils, this would be great in soaps designed for household cleaning chores, but for soap we want to use on our skin it would be too drying.
To create a soap recipe that has left over oils we have to factor that into our formula. Many lye calculators will give you the option to enter the percentage of super fat if any you would like in the recipe. Advanced soap makers will often experiment with a recipe to determine how much superfatting would make their soaps that special something. New soap makers are often taught to only super fat 6 percent. That 6 percent builds in a measure of protection to prevent any miscalculation and excess lye in the finished bar.
There are two ways to add excess fat, one is to add extra oils and fats after trace, or you can lower the lye, which is what I do, that is actually called Lye Discounting. When you add the super fat using a lye calculator you are actually discounting the lye. In some circles lye discounting is considered an advanced soap making technique and has the same outcome as superfatting a recipe, you end up with leftover oils making a less drying bar of soap. But instead of increasing oils you decrease the lye. I often call lye discounting superfatting, but there is a slight difference between to two.
Water discounting is an advance soap making technique that is used to reduce the amount of water in a recipe. Reducing water causes the lye water to be stronger, the soap batter to saponify quicker, the soap bars harden and dry out faster because less water is in the recipe means less water in the soap.
Trace is what happens when your soap batter begins to saponify and the sign that your soap batter is ready to be poured into molds.
You know your soap has reached trace when you can move a spatula across the surface and the marks left behind remain for a time. The thicker the batter gets and longer the tracings remain.
- Thin trace is when the batter is still thin, but still leaves a trace.
- Thick trace is when the batter is thick and the tracings to stay on the surface.
Gel is a stage that takes place after the soap batter is poured into the mold and becomes hot and translucent. It is part of the saponification process, a good long hot gel stage helps to fully saponify the soap batter into soap, making a harder, longer lasting and milder bar of soap.
Curing is what bar soap does after it is made, it is left undisturbed to cure for 4 – 8 weeks before use. Curing allows the soap to fully saponify and for some of the extra water to evaporate making a harder bar of soap. I personally think curing makes a milder soap.
Making Handmade Soap Post Series
If you would like to learn to make handmade soap, follow me for the next few months as I show you step by step how to make natural non-toxic soaps from scratch. This tutorial will cover everything you need to know to make your own handmade cold process bar soap, hot process bar soap, and liquid soap.
Posts In The Series
- Making Handmade Soap – Soap What Is It?
- Making Handmade Soap – How To Make Toxic Soap
- Making Handmade Soap – Terms & Definitions
- Making Handmade Soap – Safety
- Making Handmade Soap – Equipment
- Making Handmade Soap – Supplies
- Making Handmade Soap – Recipes
- Making Handmade Soap – Cold Process
- Making Handmade Soap – Liquid Soap
Let Me Know What You Think
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- Soapmaker Software
- The Sage Lye Calculator
- Bramble Berry Lye Calculator
- Handcrafted Soap Makers Guild
- Estimation of Saponification Value of Fats/Oils