Industrial Chemistry

Part IV 

Soap & Detergent Manufacture

2011

Soap & Detergent ManufactureingProcess

Hot Process

Soap (Natural)

Home MadeIndustrial Manufacturing

Cold Process

Batch Process Continuous Process

Making the Right Soap

Fatty Acids (Structure and Prosperities)

Iodine Number (Value)

Saponification Number (Value)

Amount of Base needed

Base Discount

Lauric Acid will add hardness to your bar, promotes a fluffy lather and cleans very well... almost too well. Large amounts of lauric acid will create an excessively drying product as your natural skin oils will be stripped because of its amazing cleansing abilities.

Lauric Acid

O

OH

Linoleic Acid will add conditioning and moisturizing properties to your soap bar. The only thing to really watch out for is DOS (dreaded orange spots) as it tends to go rancid more quickly then the other fatty acids.

Linoleic Acid

O

OH

Linolenic Acid will add conditioning properties and moisturizing properties to your soap creating a very mild finished product.

Linolenic Acid

O

OH

Oleic Acid will also add conditioning properties and moisturizing properties to your soap. It will not produce a very good lather though. Oleic acid gives your bar the slippery feel.

Oleic Acid

O

OH

Palmitic Acid will add hardness to your bar and a creamy/stable lather.

Palmitic Acid

O

OH

Ricinoleic Acid will add conditioning properties, a fluffy lather and some creamy/stable lather! This fatty acid is prominent in castor oil and is great for adding a luxurious lather to the finished product even if only used in small amounts.

Ricinoleic Acid

OH O

OH

Stearic Acid will offer many of the same characteristics as palmitic acid. Once again, you'll gain hardness to your bar and add a creamy/stable lather.

Stearic Acid

O

OH

Myristic Acid will add hardness to the bar, offer good cleansing properties and adds a nice fluffy lather. Again, because of its cleansing abilities, too much myristic acid will produce some what of a drying product.

Myristic Acid

O

OH

Fluffy Lather : A fluffy lather is thick and bubbly but washes away easily.

Stable Lather - A stable lather hasvery little substance but is harder to wash away.

In general, you want a combination of ingredients that produce both fluffiness and stability to your soap's lather.

What is the iodine number? The iodine value is the measure of the number of grams of iodine that will react with exactly 100 grams of the oil in question.

As a broad rule, the higher the iodine value the softer the bar and the more conditioning properties it will have. Alternately, the lower the iodine value the harder the bar and the less conditioning properties it will have. This is just a general rule as there are some exceptions.

The Saponification value (SAP)

How many milligrams of base is required to completely saponify 1 gram of an acid (oil or fat).

Example 1: The saponification value of palm oil is 142. This means that it takes exactly 142 milligrams of lye in order to saponify 1000 milligrams of palm oil.

Example 2: Avocado oil has an SAP value of 133.7. This means that it takes exactly 133.7 milligrams of lye in order to saponify 1000 milligrams of avocado oil.

Take the SAP value in the saponification table, divide it by 1000 and multiply it by the weight of the oil being used.

How to calculate the amount of NaOH ?

Example 1: Say your recipe use 2 pounds of coconut oil. To find out how much NaOH you need you must Take 191.1 (the SAP value for coconut oil)/1000 = .1911 x 2 pounds of coconut oil = .3822 pounds of lye required to saponify 2 pounds of coconut oil.

Example 2: Say your recipe calls for 9 pounds of jojoba oil. Take 69.5 (the SAP value for jojoba oil)/1000 = .0695 x 9 pounds of jojoba oil = .6255 pounds of lye required to saponify 9 pounds of jojoba oil.

How do you calculate the amount of lye needed for an entire recipe with multiple fats and oils?

Example 3: Say your recipe calls for 12 pounds of olive oil. Take 135.3 (the SAP value for olive oil)/1000 = .1353 x 12 pounds of olive oil = 1.6236 pounds of lye required to saponify 12 pounds of olive oil.

Just add the cumulative amounts of lye needed for each acid together to reach a sum total of lye needed

Superfatting and Discount

Superfatting is where you allow a certain percentage of fats and oils within your recipe to remain unsaponified by discounting your lye by a certain percentage.

completely saponify"? Each SAP value on the saponification table tells you exactly how much lye is needed in order to turn 100% of the fats or oils into soap.

What is the meaning of 5% Discount?

Example: If my recipe said 12 g would perfectly saponify the fats, I would multiply 12 g X .95 = 11.4 g

Example 2: Your recipe consists of 4 pounds of coconut oil, 1pound of avocado oil and 3 pounds of castor oil. How much lye is needed for this recipe? Use 8% lye discount

Take 191.1 (SAP value of coconut oil)/1000 = .1911 x 4 pounds = .7644 pounds of lye to completely saponify 4 pounds of coconut oil. Now multiply .7644 pounds x .92 = .7032 pounds, which is the discounted amount of lye to use in order to saponify coconut oil in a recipe.

Solution

Now take 133.7 (SAP value of avocado oil)/1000 = .1337 x 1 = .1337 pounds of lye to completely saponify 1 pound of avocado oil. Now multiply .1337 pounds x .92 to get .1230 pounds, which is the discounted amount of lye needed in order to saponify avocado oil in a soap recipe.

Now take 128.6 (SAP value of castor oil)/1000 = .1286 x 3 = .3858 pounds of lye to completely saponify 3 pounds of castor oil. Now multiply .3858 pounds x .95 (because you only discount castor oil by 5%) to get .3665 pounds of lye to saponify castor oil in a recipe

Now add your totals together: .7032 pounds + .1230 pounds + .3665 pounds = 1.1927 pounds of lye. This is the amount of lye that you will use in this example soap making recipe to saponify your fats and oils at a discount so that for skin care purposes some of your fats and oils remain unsaponified.