Let's Talk About Soap....
And When it Fights Back!
So... you decided to make some soap. You gathered your fats, your butters, your oils, clays, lye. Now you might ask, how much lye do I need, and your internet is out, so a soap calculator isn't available to you. What happens if I add too much lye? What if I don't mix the batter enough? What if I mix the soap batter too much? Why are people dressed in hazmat suits to handle lye?
Let's Talk About Lye.
Lye. Sodium Hydroxide. The start of every Fight Club joke. This stuff is no joke. Lye+Moisture+Fats=Soap. That tells you everything you need to know, if some gets on your bare skin. So gloves, apron, and goggles are a necessity. 1 part water to 1 part lye. Lye to water. Never the other way around. EVER. EVER EVER. Say it with me. Lye to Water. Lye to Water. Now, you got a 50% solution. This is the magic potion. Pre-batch a quart. Equal parts. Set it aside.
Okay, so now you want to actually make the soap. For around 10 bars, you need about a kilo of oil. But depending on the oil, the amount of lye changes. Each oil has its own saponification value. This will tell you how much lye needs to be in the actual recipe. Soap calculators online exist, but as it was stated, the internet is down, and you NEED to make this soap. You take the weight of the oil multiply by the SAP value. You got five oils in the batch. Add up those products. That's how much lye needs to be in the batch. Easy, right?
What if you got the ratio wrong and your recipe ran lye-heavy — too much sodium hydroxide for the oils you've got. You stick blend it. Pour into the mold. Step away for a day. When you come back, SHOCK! Literally. See, the tried and true method of testing if all the lye has reacted is the zap test. Rub a bit of the soap on your finger, then touch it to your tongue. If it's soapy, you're golden. If it's battery acid, well, you got some free lye unsaponified. (In young soap batter, this is normal. A week later plus crumbly texture... that's a problem.)
So you came back, zap test, and the metallic shock is enough to blow your hair back. And the texture! The texture is crumbly. Chalky. What happened? There wasn't enough oil to eat all that lye! The oil and the lye water melded, but there was sodium hydroxide left over with nothing to react with. But hark, all is not lost! You can save this batch. Heat and more oil. Grate those crumbly pucks into a crockpot or a stainless steel pot, add the proper oil, heat it until it's melted, and let it cook for a few hours. It won't be as pretty as cold process soap, but hot process soap still does the job, and it's historically older, so not a loss.
Stick Blenders and Trace.
Aright. So, let's go back. You got your oils. You have your proper amount of lye mixed in. It's time to stick blend. You slowly add your lye water to the oils. The batter darkens immediately. You stick blend for a moment. It looks blended? Maybe? Is it thickening. Panic sets in. You pour the batter, but it's almost liquid. You fill the molds. Step away, come back the next day, and the soap is soft, and grainy. You take it out of the mold, and place it on the rack. You come back the day after that. Many a'beads are forming on the outside. You zap test it. 9-volt to the face. Well, that's a soap that didn't fully emulsify, and there may be loose pockets of unreacted lye. There may be separation in the soap, and unsaponified portions.
Luckily, you have a second batch ready to go. You add the lye water, but you know better this time. You stick blend the batter like it's your job. Up, down, and around. The batter quickly goes from light gravy, to pudding, to globs of raw soap batter (heavy trace). You try to pour it, but this soap is seizing on you. Add it to the mold. Let it set, and fix it in post.
Wow! A third batch? Here we go. Add the lye water. Blend it lightly. First is emulsion. Then comes light trace. This is when marks on the batter remain for a second. Maybe less. It's not thick yet, but it's getting to hollandaise texture. Now you pour. Pour quickly. Pour, pour, pour, as it begins to thicken itself into medium trace.
Okay. So now it's the molds.
You come back the next day. Remove the soap, place it on the rack.
Time for the cure.
The Cure.
Soap needs time. Six weeks is average if you aren't using palm oil, or a soap hardener. For olive oil heavy soaps, you need to allow the softer nature of the saponification process to have enough time to harden the bars. No one wants soap that melts in three uses.
On the racks for six weeks.
Lather, rinse, repeat.
Sometimes soap doesn't behave the way we want. Sometimes it weeps. Sometimes there is too much lye. Sometimes there isn't enough lye, where the soap is too oily, risks rancidity, and doesn't cleanse as well. If you don't mix enough, problems abound. If you mix too much, you gotta scoop it like ice cream. Every soap maker messes up a batch of soap at some point. It's how you react in a slippery situation that makes all the difference.