The classic cold process soapmaking method

Please notice these suggestions are made available as general information only. Soap making from scratch implies working with dangerous substances, such as caustic soda in its pure form (NaOH - sodium hydroxide, or KOH - potassium hydroxide). We do not assume or accept any responsibility for, and will not be liable for the accuracy or inappropriate application of any information whatsoever in any material on this website.
If you prefer to avoid working with strong lye solutions, you can choose the easy road and purchase a natural soap base for hand milling, also known as rebatching or, less appropriately, as remilling.

Overview
I am placing this set of instructions on my Website basically because it has become difficult to obtain on the Internet reliable information about the basic cold process (CP) method of soapmaking. While there is nothing new in the general concept, I have attempted to describe the process in a way that even beginner soapmakers can understand.

It is however important to note that soapmaking is not suitable for everyone and all. Safety considerations are paramount when working with "lye", and we assume the reader is 100% aware of the risks, and can take total responsibility for the consequences.

Before attempting to make soap for the first time, you might like to check out some basic safety considerations for a run down of the precautions required when working with strong alkalis. For further and general background information about soap and soapmaking, please refer to my soap methods overview and my versions of hot process soap and discounted water cold process methods.

What is CP soap making?
In short, CP (cold process) method is a way to make soap without applying any extra heat. By definition, it is impossible to make really "cold" soap. This is because soap is the product of a chemical reaction (called "saponification") where fatty acids, combined with an alkali, give a salt (=soap) as the final product. You probably remember from your school days that this type of chemical reaction is exothermic - in other words, it creates heat.

It should be noted however that for saponification to occur, oils, fats and the alkali must all be in liquid form. For this reason, water is needed to dilute the alkali, and oils or fats that are solid at room temperature must first be placed on a heat source to melt.

The alkalis used for soap making are sodium hydroxide (chemical formula: NaOH), and potassium hydroxide (chemical formula: KOH). In their pure form, both NaOH and KOH are solid (powder or flakes). When we talk of "alkali", we refer to sodium or potassium hydroxide, in general. When we talk of "caustic soda", we usually refer to the same thing - whereas a "caustic solution" or "lye solution" is the strongly alkaline liquid made by dissolving pure NaOH or KOH in water.

In case you're wondering, there is no way for making soap, and even less natural glycerine soap, without an alkali. For the fatty acids (fats and oils) to turn into soap, caustic soda must be used - no alkali, no chemical reaction, no salt and no soap. However, properly made natural soap contains some extra fatty acids (which are very good for your skin), plenty of natural glycerine (which, too, is good for your skin), and no free alkali - which is quite the opposite to what happens with factory soaps... even the mildest!

Temperature considerations
There is no general agreement as to which is the optimal "starting" temperature for a successful batch of soap. The suggestions that follow come from my personal experience and observations, but I am not setting any "laws". Different soapers have different opinions, and I respect them all.

Double check and make notes!
Saponification calculators, pen and paper are a soaper's best friends. Whichever the source of your recipe, always run the amounts through a SAP calculator and make sure the amount of caustic soda is within the safety threshold (from 3% to 10% superfatting, 0% superfatting for laundry and cleaning soaps only).
Also.... don't forget to make notes. Troubleshooting a problem batch is impossible, unless we know exactly what we did, how we did it and in which order. No notes also mean replicating a successful batch might be very difficult. So don't be afraid... and write :-)

My personal preference is to work at medium to low starting temperatures, and to measure by weight all ingredients, including water, and only excluding the essential oils, which I measure in milliliters. Also, I use a stick blender, which cuts down enormously on stirring times. In detail, here is what I suggest you do:

1. After choosing the recipe and calculating the amounts of the ingredients (oils/fats, caustic soda, water, fillers and fragrance), prepare your working space - i.e., put away things that might become contaminated and cover the surface with a layer of old newspaper.
2. Collect all the equipment, the ingredients, and the containers and tools you will need for this batch of soap.
3. Find a few old towels, or a blanket, or some heavy rags for insulating the moulds. If you're planning to fill the moulds to the brim, you'll also need a roll of baking paper (or plastic film, or some heavy duty plastic).
4. Prepare the lye solution: measure the required amount of cold water in a heat resistant container. I use a heavy plastic (HDPE) jug, which has a fitting lid.
5. Place this container in the sink, and fill the sink with enough water to reach the level of the water in your container or more. Just make sure the container doesn't float too much (it will get heavier when you add the caustic, anyway).
6. Wear your protective clothing (gloves, mask etc.)
7. Measure the required amount of caustic soda in a clean, dry container.
8. Add the caustic soda to the water a little bit at a time, but not too slowly, and stirring continually with a long handled tool (I use a paint stirrer).
9. Avoid breathing in the fumes. If you can, I suggest you mix your lye solution outside (wind at your back, if any ;-). Make sure there is a water tap close by, in case of accidents.
10. Cover the container with the lye solution.
11. Measure your oils or fats directly in your soap pot. I start with the solid oils/butters to avoid splashes.
12. Place the soap pot on medium heat.
13. While the oils/fats are melting and the lye is cooling down, assemble, measure and organise your extra ingredients.
14. Line the mould (if you're using a log, slab or divider mold), or otherwise prepare your moulds (some types of plastic tray molds require greasing)
15. Determine where to place the moulds, and place a towel or thick layer of newspaper under the moulds. Remember you will not move the moulds for the first 12 to 24 hours - so choose a spot where the soap can be left undisturbed!
16. When the solid oils/fats are melted, turn the heat off under the soap pot and measure the temperature.
17. As I mentioned, I like working at medium to low starting temperatures. I suggest you start getting ready to mix your soap when the oils are around 45º C / 110º F.
18. If the fats/oils are warmer than this, just go and do something else while you wait - or you can place the soap pot in a sinkful of cold water to speed up the process.
19. When the oils are at the desired temperature, check the temperature of the lye solution. Typically, this will be lower than the temperature of the oils - which is perfect!
20. If the lye solution is still much warmer than the oils, I suggest you try and cool it down by adding more cold water to the sink.

Read More : Process soapmaking method

source : aquasapone.com.au