Soap is important to our society today and it has formed the integral part of the society. However, the current widespread use of soap is only a very recent occurrence, despite the fact that it has been in used since 2600 years ago. The first recorded manufacture of soap was 600 B.C.E. However, during that period , the people used soap medicinally, and it was until 200 B.C.E that it was used for cleaning and not until 1900 C.E that it began to be commonly used in the Western world. Early during the 21st century the first synthetic detergents were manufactured. Soaps are the products of the reaction between a fat and sodium hydroxide:
Fat + 3NaOH Glycerine + 3 Soaps
Basic Steps for Making Soaps Industrially
Soap is produced industrially in four basic steps:
- Glycerine Removal
- Soap Purification
STEP 1: Saponification
During this process, a mixture of animal fat (tallow) and coconut oil is mixed with sodium hydroxide and heated. The soap produced is the salt of a long chain carboxylic acid.
STEP 2: Glycerine Removal
The nature of glycerine is that, it is very valuable than soap. Some is left in the soap to help make it soft and smooth. Soap is not very soluble in water, whereas glycerine is, so salt is added to the wet soap causing it to separate out into soap and glycerine in salt water.
STEP 3: Soap Purification
Any remaining sodium hydroxide is neutralized with a weak acid such as citric acid and two thirds of the remaining water is removed.
STEP 4: Finishing
Here at this step additives such as preservatives, color and perfume are added and mixed in with the soap and it is shaped into bars for sale.
On the other side, detergents are commonly related in structure and function to soap, and for most uses they are commonly efficient than soap. The actual ‘detergent’ molecule, detergents usually incorporate a variety of other ingredients that act as water softeners free-flowing agents.
CHEMISTRY OF SOAP AND DETERGENTS
Soaps and detergent contain a surfactant as their active ingredient. Mainly, we know this as an ionic species consisting of a long, linear, non-polar ‘tail’ with a cationic or anionic ‘head’ and a counter ion. The tail is water insoluble and the head is water soluble. This process results to the following;
- The surfactant molecules becomes a wetting agent
- The oily dirt particles are allowed to form an emulsion with water
The Soap Manufacturing Process
The main essence of soap production is the saponification reaction:
This reaction is exothermic and progresses quickly and efficiently at around 125oC inside an autoclave type reactor.
The most popular fats and oils used are beef or mutton blend (tallow), coconut oil and palm kernel oil. Different oils used produces soaps of varying hardness, odor and lathering, so the ratios of the oils used are closely monitored to produce a blend with the most desirable characteristics for the most reasonable cost. However, pure soap is hard and easily oxidized, so various additives are added to correct this and to make a more aesthetically pleasing product. The first of such addictive is glycerine, which is produced during the saponification stage. Glycerine makes the soap smoother and softer than pure soap.
Four Methods of Making Soap
There are four basic methods for making soap at home:
- Melt and Pour- melt pre-made blocks of soap and add your own fragrance
- Cold Process- the most common – making soap from scratch with oils and lye
- Hot Process- a variation of cold process where the soap is actually cooked in a crockpot or oven
- Rebatching- grinding up bars of soap, adding milk or water, and re-blending them
To start with, we’ll discuss the two most popular methods of soap making, Melt and Pour and Cold Process Soap Making.
Melt and Pour Soap Making
Making soap with a “melt and pour” base is sort of like making a cake with a cake mix. What you lose in control of your ingredients and customization of your recipe, you make up for in safety, ease, and convenience.
With melt and pour soap making, you buy pre-made blocks of uncolored, unscented soap “base” from a craft store or soap supplier. You melt the soap base in the microwave or a double boiler. When the soap is fully melted, you add your fragrance, color and/or additives. Put it in a mold, and voila, you’re done. The soap is ready to use as soon as it hardens.
To get started making melt and pour soap you only need:
- A countertop or other clean workspace with a microwave or double boiler
- A heat-resistant bowl for the microwave
- A couple of spoons or whisks
- Some melt and pour soap base
- Fragrance, color, or additives, as desired
- Something to mold the soap in
- A set of measuring spoons
Pros of Melt and Pour Soap
- It is an easy and inexpensive way to making soap
- No need to deal with dangerous/wrong lye mixture
- A lot of ingredients to start
- As soon as it hardens, the soap is ready to use
Cons of Melt and Pour Soap
- You don’t have control over your ingredients
- Melt and Pour are not quite as “natural” as other methods.
- Your soap is only as good as the base you purchase
Cold Process Soap
If making melt and pour soap is akin to using a cake mix, “cold process” is making your cake from scratch. You control everything that goes into the pot, and you can make it as “natural” as you want. However, your setup is a little more complicated, and you’ll need to learn a few techniques of the craft first.
To make cold process soap, you heat the oils in your soap pot until they’re approximately 100 degrees. Slowly add the lye-water mixture and blend the soap until it thickens to “trace”. After the mixture reaches trace, you add your fragrance, color, and additives and pour it into the mold. The raw soap will take about 24 hours to harden, and about four weeks to cure before it’s ready to use.
To get started making cold process soap, you’ll need:
- Some animal fats or vegetable oils
- A soap pot and some other easily found tools and equipment
- Natural or synthetic colorant, as desired
- A cool, dry place to let the soap cure
- A flat, uncluttered workspace with a heat source and access to water
- A pitcher of lye-water
- Fragrance or essential oil, as desired
- A mold to pour the raw soap into
Pros of Cold Process Soap Making
- The soap is truly made from scratch
- You control all of the ingredients in the soap
- You can tailor your recipe into unlimited variations
Cons of Cold Process Soap Making
- You need to learn how to safely work with lye
- You’ll need more ingredients and tools to start
- It takes longer to make and there is more cleanup involved
- You need to wait several weeks before your soap is ready to use
Step-by-Step Instructions to Making Cold Process Soap
Whichever method you choose, you can make great soap. Work patiently, and follow the instructions closely to start with. Once you’re familiar with the basic steps, you’ll be able to let your creative inspirations flow and make all sorts of wonderful soap creations.