Soap 101 Making Lye

 

 

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A Timeline of Soap Making (from Soap Making Resource)

2200 B.C. - Although it is believed by many that soap's history actually began around 2800 B.C. in Babylonia (where historians found a barrel containing a soap-like substance) unarguable proof of soaps existence was first provided by a 2200 B.C. Mesopotamian clay tablet with an actual soap recipe inscribed on it. This ancient soap making technique described mixing potash and oils to form a cleaning agent.

1500 B.C. - Egyptian manuscripts describe a matter created by combining animal fats and vegetable oils to create a soap-like substance. The ancient documents go on to explain another type of soap that is used in the production of wool.

200 A.D. - The very first allusion to soap making in literature occurred by a famous Greek physician named Galen.

600 A.D. - soap making guilds were formed and the modern formula for soap that we use today was created.

900 A.D. - soap started to be produced commercially and sold for .3 Dinars per bar.

c1700-c1800 A.D. - During the industrial revolution, soap began its production in factories and stopped being produced in the home kitchen.

Currently - Soap is being produced in the same way as it was centuries ago after the industrial revolution. As almost all people in this modern age purchase and use commercially manufactured soaps, the history of soap making is at somewhat of a standstill.

 

 

 

What is Soap?

By chemical definition, soap is the salt of a fatty acid, a triglyceride, which are three molecules of fatty acids attached to a single molecule of glycerol (glycerin).

The bars we use for cleaning are simply animal or vegetable oils treated with a strong alkaline solution called lye (sodium hydroxide).

Lye catalyzes the saponification process, the hydrolysis of fats into free fatty acids, which then combine with alkali to form crude soap.

The liberated glycerin by-product is either left in the soap or collected, depending on which soap-making process is used.

 

 

What is Lye?
There is a difference between homemade, or original lye, and commercial lye.
 Homemade lye is Potassium Hydroxide and can be made rather simply at home from wood ashes. 

Potassium Hydroxide makes a softer soap, so the fat or oils used will need to be beef tallow (beef fat) or even lard (pig fat).   These are 'harder' fats.

You can use other fats, but the finished product will be much softer.
Commercial lye is Sodium Hydroxide, which is much more complex to manufacture, and is often used in drain openers.

In order for commercial lye to work properly in soap, it must be pure sodium hydroxide, which is becoming difficult to find in grocery stores.

If you are not sure if your lye is pure, you can look at the crystals. If you see flecks of gray or black, you should avoid it when making soap. You can also ask the manufacturer.

Sodium Hydroxide is more powerful that Potassium Hydroxide so its SAP (saponification) value is different. 

The weight of Sodium is 40/56.1 as opposed to Potassium.
   

 

Useful Resources!
Soap Making Safety Procedures
Lye Calculator™
Make Lye in a plastic bucket

Your 'Basic' Lye Machine
This illistration is from the Jan/Feb 1972 issue of MotherEarth News.
Lye in a pair of Plastic buckets.
Rough Wood bin Lye maker.

The 'V' is made from Shiplap boards.

The two ends are solid with on side haveing a small hole drilled thru to catch the liquid lye.


Once you have a strong lye water solution, you can dry the lye to a crystalline form.

In crystal form, lye is easier to store and it also works well for many soap recipe measurements.

Drying the lye can be accomplished by placing the lye water in the sun and allowing the water content to evaporate.

As with the lye water, use caution with the lye crystals.

Remember, do not use a metal container.

 

Two Sample Soaps
  Lard (Lye) Soap Castille Soap
16 oz Lard
2.06 oz lye
4 – 6 oz water
 


8 oz Olive Oil
4 oz Coconut Oil
4 oz Castor Oil
2.19 oz lye
4 – 6 oz water

 

WARNING: Always add your solid form lye, sodium hydroxide or potassium hydroxide, to the liquid. If the liquid were added to the solid form lye a violent reaction could result.

This means you could have a "volcano" erupt out of your container.   Believe me you DO NOT want this to happen!

Basic Soapmaking Instructions
  • While wearing safety goggles and neoprene gloves, combine solid lye and liquid, stir well. Set aside and allow to cool (100° F to 125° F). This is best done outside while you are standing upwind.
  • Combine oils and heat gently. Once the fats and oils are melted allow the temperature to drop to 100° F to 125° F.
  • Combine lye solution and melted oils. Be careful not to splash while combining the mixtures.
  • Stir until the mixture traces. If tracing takes more than 15 minutes, which it often does, stir for the first 15 minutes, then stir for 5 minutes at 15 minute intervals.
  • Tracing looks like a slightly thickened custard, not instant pudding but a cooked custard. It will support a drop, or your stir marks for several seconds.
  • Once tracing occurs...
    Pour raw soap into your prepared molds. After a few days the soap can be turned out of the mold. If the soap is very soft, allow it to cure for a few days to firm the outside.
  • Cut soap into bars and set the bars out to cure and dry. This will allow the bar to firm and finish saponification. Place the bars on something that will allow them to breathe.

 

Saponification Table
You take the weight of your Fat x the SAP factor to give you the weight of Lye for a batch of soap.
Base fat SAP  (Potassium) SAP (Sodium) Hard/Soft cleansing fluffy lather stable lather skin care
lard 0.1945 0.1387 hard good no yes fair
tallow 0.1971 0.1405 hard good no yes fair
soybean oil 0.1906 0.1359 soft good no yes fair
olive oil 0.1898 0.1353 soft good no no great
castor oil 0.1804 0.1286 soft fair yes yes great
coconut oil 0.2680 0.1911 hard great yes no fair
palm oil 0.1992 0.142 hard great no yes fair
peanut oil 0.1921 0.137 soft fair no yes great
jojoba oil 0.0975 0.0695 soft fair no yes great