In a nutshell, soap is made when oils are combined with sodium hydroxide (lye). That's really about it.
Let's expand a bit on that, though. Here's where I lay some chemistry on you. I promise it won't hurt much. To make soap, a chemical reaction has to take place between an acid (the fats and oils in a soap recipe) and a base (a lye solution of sodium hydroxide and water). This chemical reaction, which is called saponification, produces soap and glycerin, a natural by-product of soapmaking.
|The chemical structure of a typical soap|
See, each molecule of sodium hydroxide combines with a molecule of oil. During saponification, triglycerides in the oils break down into fatty acids and glycerols. The fatty acids react with the sodium ions, creating sodium compounds that are better known as soap. (So soap is chemically a salt. Cool, huh?) And where does all of that skin-loving glycerin that I mentioned earlier come from? The newly liberated glycerols react with the hydroxide ions to create glycerin.
Of course, you can't just dump some sodium hydroxide into some oils and get soap. There is a process.
|Dig my look?|
Here are the basic safety rules: Suit up with goggles, gloves, long sleeves, long pants, and close-toed shoes. Take care to not breathe the lye fumes. Standing back and running the exhaust fan is usually enough, but wear a painter's or dust mask if you want to. If you get lye or raw soap on yourself, rinse thoroughly with water and then rinse with vinegar. (I always have a spritzer of vinegar handy.) Protect your countertops and appliances, too. I take a tip from Dexter and cover everything with plastic drop cloths. I also lay down paper bags so I have a place to rest my soapy utensils.
A few words about equipment: I use either heavy-duty plastic (polypropylene is my plastic of choice - the kind with the recycling code with the "5" and "PP" on the bottom) or stainless steel for making soap. Never use aluminum, tin, copper, teflon, or any other metals, as they will react badly with lye. I also do not use glass - over time, lye can etch tiny cracks into the glass and one day it may decide to just shatter.
|Kitchen prepped for soapmaking|
|Adding lye flakes to water (inside a dishpan in case of any spills); stirring lye solution in ice bath|
|Adding lye solution to oils; emulsifying lye and oils with stick blender|
|Look closely. See the trails of soap on the surface? That's trace.|
Soapmakers look for something called "trace." Trace occurs when the soap batter is completely emulsified and will not separate into a watery, oily mess. How do you test for trace? Dip a spoon or spatula into the soap and dribble a bit on top. If the dribbles leave a trail of soap that stays on the surface for a couple of moments before sinking back into the batter, that's trace. Trace can be light or heavy, depending on how long you mix it and what consistency you want. Lighter trace is good for swirling, heavier trace is good for layering.
Once I've reach my desired level of trace, I pour my soap into my mold. Some molds (like silicone, plastic or acrylic) don't need to be lined, but others (like wooden molds) do. To line a mold, I use freezer paper with the shiny side facing in.
|Freshly poured soap in the mold|
After about 4-6 weeks of curing time, the soaps are ready to use!
And that's pretty much it! Now you know the basics of soapmaking. I hope it was interesting!
Until next time ...