1. GoTo   What do the "'Individual" and "Combined" columns on the left mean?


2. GoTo   What are the best values for Hardness, Cleansing, Condition, Fluffy and Stable?


3. GoTo   What is the right amount of water for any given soap recipe ?


4. GoTo   What is superfat or discount?


5. GoTo   Why is a minimum 5% discount recommended?


6. GoTo   What is milk fat (bovine)?

The "Individual" column displays the soap qualities and fatty acid percentages of the individual oil/fat selected in the center column. Notice that as you click on each oil, the numbers in the "Individual" column change to represent the qualities for that oil.  The numbers in the "Individual" column will always display the qualities of the oil currently selected in the oil list, even after clicking "Compute Recipe".

The "Combined" qualities display the soap qualities and fatty acid percentages of all the oils listed in your recipe (the right column). These are displayed after you click "Compute Recipe".  If you change an oil in your recipe or change a percent, "Compute Recipe" must be clicked again to update the numbers in the "Combined" column.

This is a tough question.  There is no one right answer. The explanations required a page of its own: Go to the Soap Qualities page.

The water in your recipe is required to separate the oils and fats into fatty acids and glycerine. This process, involving both the water and the lye is called hydrolysis and makes the fatty acids available to react with the lye and make soap. Most, but not all, of the water evaporates during the soap making process. More water is required for making soap at higher temperatures than at lower temperatures.

In SoapCalc, the percentage of lye is calculated beased on how much of each oil you have in your recipe - that lye amount does not vary for any given recipe. That leaves the question of how much water to use (BTW: ALWAYS add lye to water, not the other way around). There is no "right or ideal" number to choose for how much water. The amount of water can be calculated as: 1) a percentage of the total oil weight, 2) as percentage of lye in the water & lye solution - this is referred to as lye concentration. or 3) a water to lye ratio like 2.6:1

For the default water amount, SoapCalc uses:

• A default value of water as 38% of total oil weight.
• Lye as about 28 % of the water & lye solution. This will vary somwhat from recipe to recipe.
• A water to lye ratio of about 2.6:1. This too will vary somwhat from recipe to recipe.

A default value of water as 38% of total oil weight is a safe starting point and will make a decent bar of soap for both CP and HP. You can experiment from there.

Caution: Lye solutions with higher concentrations of lye will speed up the chemical process.  Your oil and lye solution mixture could easily bubble out of the pot and spill over your stove or table (or you). This happens quickly.   It is commonly called the volcano effect.  Beginners might want to start with the default 38% "Water as % of Oils".   more information...

When lye is greater than 40% of the water and lye solution, the hydrolysis process may not be complete and your soap may end up with some small areas containing unused lye. It is possible to go higher than the the 40% limit - but only for experienced discount water soapers. SoapCalc will pop up a warning if the lye concentration is greater that 40% - but the calculation will continue anyway.

If you use all the lye necessary to exactly saponify all of the fatty acids in the oils, the soap would have no excess lye or excess oil (next to impossible without a chemistry lab). It would have a zero discount and there would be no superfat.  If you discounted the lye (let's say by 5%) 5% of the soap would contain oils that have not chemically reacted with the lye.   i.e. all the lye was used up in reacting with 95% of the oils. The soap would have a 5% superfat. These unsaponified oils are good for conditioning the skin. A soap with no discount or superfat will clean better. However, other than conditioning the skin, there are other important reasons to discount the lye (or superfat the soap).  Please see the next question.

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The SAP values used to calculate the amount of lye - in this calculator and in others - is an average. If you purchase oils/fats that have been assayed by a chemical lab, you will know the exact SAP value of the oils/fats. (Your wallet will be much thinner too).  If you weigh these oils, and the lye, on very precise labratory scales, you can confidently make a zero discount soap.

One of my references gives the Potasium Hydroxide (chemical symbol KOH) SAP value for coconut oil as 250-264.   The SAP for other oils is specified similarly as a range of values. Why? There are many variables that contribute to the chemical qualities of a carrier oil. Here are a few to give you the general idea:

• Species of the botanical used to make the oil.
• Geographical location of the source botanical. i.e. variable climate.
• Varying types of processes used to create the oil.
• Seasonal differences in when the botanical was harvested.
• Maturity of the botanical when it was harvested.

The minimum 5% discount/superfat is recommended to allow for these variances so you do not end up with soap that contains unused lye.

It is not butter, half and half, or heavy cream. It is the pure cream contained in those products.  It is made by spinning natural whole milk (straight from the cow or other bovine animal) in a centrifuge like device.  Some soapers have access to natural whole milk and can buy a cream separator or can buy milk fat from a local dairy.  Heavy cream has a fat (cream) content of between 36% and 40%.

Check these links for more info:

Cream Separator
Butter Manufacture
Cream Separator
What is Heavy Cream?