Great explanation of the different methods!! I started with Melt and Pour but soon moved on to Cold Process which is what i use to make my soaps now.
Contrary to what most people believe, soap making isn't that hard to do if you are equipped with sufficient information about it. As chemists would put it, soap is what you get when you combine oils or fats with a strong alkali solution (more popularly called lye). This process is what soapmakers call saponification.
So why is soap fit for cleaning dirt off our bodies you ask? Ask yourself this question. What happens when you use soap on a soiled surface? The soap "loosens" the dirt particles and makes it easier for rinsing. By analogy, soap molecules are like two-poled magnets. One end holds on to water molecules, the other end holds on to grease particles. The latter end makes it possible for those grease molecules to be dissolved in water, which under normal circumstances would be near impossible because water and oil don't mix.
Back to saponification. When people hear the phrase "soap making" they immediately associate it with lye. Quite frankly, essential soap making does involve the handling of lye but there are actually 4 basic methods of crafting soap. Two of which will require you to handle lye solution while the other two won't. Allow me to give you a quick overview of those methods.
Cold Process
This is probably the most commonly used soap making method. This involves making soap from scratch using fats or oils, and lye. It takes more time to create cold process soaps than it is to make soaps through the other methods. This method provides for a certain degree of freedom when designing recipes. The following are the Pros and Cons of cold process soap making:
PROS
- You have control over which ingredients to use in your soap.
- Your soap is made from scratch.
- You can create recipes that serve various purposes, like anti-acne soap or whitening soap, since you are allowed a bit of flexibility in the choice of ingredients.
CONS
- This method requires that you handle lye. You'd have to learn how to create lye solution and how to handle or store it safely.
- May not be so appealing to beginners since this process requires a LOT of utensils and materials to start.
- This method takes time to complete. Especially since you will need to wait for 2-6 weeks before it's safe to use your soap.
- More cleanup to do afterwards.
- Requires exact measurements of lye and fat amounts and computing their ratio, using saponification charts to ensure that the finished product is mild and skin-friendly.
- You need to use EXACT measurements of fat and lye and you also need to compute the right ratio between them. You'll need to learn how to use SAP charts and lye calculators to make sure that your soap is skin-friendly.
Hot Process
This is where the saponification stage in cold process is sped up by boiling lye and fat together at 80 to 100 degrees Celsius. The mixture is stirred as it is "cooked" until it goes through the various stages of saponification. Once ready, excess water is evaporated and the soap is poured into molds.
PROS
- Less cleanup to do afterwards (compared to cold process)
- The soap you make is ready more quickly.
- You use less amount of fragrance than you do with cold process.
CONS
- It's difficult to take out of plastic molds. You would have to modify your recipe and method in order to make your soap work well with plastic molds (i.e. use more oils).
- Again, you have to learn how to handle lye safely.
- Really requires attention to detail since you will have to be more careful as you "cook" the soap.
- You will have limited time to add colorants, additives and fragrances, and to pour soap into your molds.
Melt-and-Pour
This comes next to cold process in popularity among soapmakers since it is probably the easiest to make. Note that the term "melt and pour soap making" is in actuality a misnomer, since no actual saponification is observed in this method. In this process, pre-made bars of glycerin soap are melted in either a double broiler or a microwave oven in 30-second bursts. Once melted, colorants and fragrances are added then the soap is then poured into molds.
PROS
- No lye involved.
- Easy and inexpensive, it's a method that's great for soap making beginners.
- You only need a few ingredients to begin.
- No curing necessary. Your soap will be ready to use immediately after it hardens.
- You are given lots of freedom when it comes to aesthetics - in casting your soap and in adding fragrance to it.
CONS
- You have limited control over the ingredients in your soap. Your final soap is only as good as the soap base you buy.
- Some soap base manufacturers add chemicals to the glycerin soap you're using to make it melt better or to increase its lather. Your soap may not be as natural as you think it is.
Rebatching
This method is also called hand milling. It is technically another form of cold process soap making. Rebatching is frequently used by soapmakers as a workaround for adding fragrance or essential oils that cannot withstand the high temperatures involved with cold or hot process soap making. This is also another technique used to salvage "failed soap experiments" or soaps that may have cracked or separated while being saponified. Just like in melt and pour soap making, there is no saponification observed in rebatching. In this method, solid soap is finely grated and then remelted with liquids (either water or milk) using various techniques. The choice of liquid affects the texture of the melted soap later.
PROS
- Helps you get the most out of fragrance or essential oils since the additives aren't affected by the harsh lye (since rebatching is done post-saponification).
- This method can be used to test out fragrance blends.
- You can use this to save your "failed experiments".
CONS
- Oftentimes, the soap never really remelts completely. Most of the time the soap ends up being a gloppy, chunky, thick and opaque mass of soap that's hard to get into molds.
- It's likely that air bubbles will get trapped in the bars and it will be hard getting a smooth surface for your soap bars.
- You have to exert a whole lot of effort getting your soap mixture to get squished into the molds. Some soapmakers prefer to put on gloves and really force the soap glob to fit in the mold. Others prefer to bang the mold against the solid surface of a table or counter to get rid of any trapped air bubbles.
