How-to: Make Cold Process Soap

Posted by A69143a5 tiny Jen on nov 12, 2014 under How-To

Homemade soap is the perfect gift for the holidays or just about anytime, and, once you have the ingredients on hand, you can whip up a (large) batch in about an hour. It's also a project that really lends itself to experimentation and customization. I learned a couple of years ago in our soap-making class and find it's a project that really delivers - it's super satisfying, relatively easy, and makes for a great finished product. 

What's soap, anyway? 

When you're making soap, you're making a salt by combining an acid with a base. Your "acid" in this case is your oil, even though oil is barely acidic. Your (very strong) base is a lye and water solution, combined and then allowed to cool before being added to the oils

ACID: Base Oils = 28 ounces total 

For this recipe, we use a mix of canola oil (14 ounces), olive oil (6 ounces) and coconut oil (6 ounces). Coconut oil helps keep the soap solid since it's a solid at room temperature.   

BASE: Lye + Water = 12.5 ounces total

For this recipe, it's 8.5 ounces of water and 4 ounces of lye. 

Before making your first batch, you'll need one specialized ingredient: sodium hydroxide, also known as lye.

Lye can be ordered online, and this $14 bottle wil last for ages. It's always good to get food-grade lye, rather than lab-grade, and I like to use the microbeads, as they make it way less likely you'll inhale anything. You also may know lye as drain cleaner and the thing that gives soft pretzels their shiny, browned skin. 

Lastly, there are a couple other pieces of hardware you may need to track down - a thermometer, a hand blender, and a scale. 

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Mix lye solution

Safety first! Be sure to wear goggles, gloves, and a mask while you're working with lye and only do it in a well-ventilated area. Lye causes chemical burns and is incredibly nasty stuff. If you do get any on your skin, use vinegar (rather than water) to neutralize it. I'd recommend reading up on lye safety here before making soap at all. 

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The first thing you'll do is measure your water into a bowl: 8.5 ounces. Then add in your lye beads (4 ounces). Don't add water to lye, always add the lye to the water! 

Give it a quick stir with a wooden spatula and place in a well-ventilated area to cool. The mixture will become hot and milky colored (below). It will also release steam immediately, so be careful when you're moving the bowl to another location. When first mixed, the solution is too hot to add to the oil mixture, so you'll need to wait for it to cool down in order to safely add it to your oil. 

Mix base oils 

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Meanwhile, while your lye solution is cooling down, mix together your base oils.

This can be just about any combination of oils, but you're looking for 28 ounces total. Here, we used 12 ounces of canola, 8 ounces of coconut (warmed up to a liquid) and 8 ounces of olive oil. Using canola helps keep the price of the ingredients down, and I've actually used all canola when I didn't have other oils on hand. It's really up to you and how much you want to spend on your soap.   

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Mix oils with lye solution

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Now comes the fun part. Once your lye solution is cooled down to about 125 degrees (or lower) Farenheit, add the lye solution to your bowl of base oils and mix. You can do this by hand, but it will take ages, so we'd recommend using an immersion blender. I have a cheap immersion blender that I use just for soap - that way, you don't have to worry about cleaning it super thoroughly after each batch. 

Blend until you reach "trace"

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This part takes awhile. You'll want to mix the mixture with the blender until "trace" appears. Trace is, basically, when the mixture is thick enough that you can see a trace left behind when you move a tool through it. It always reminds me of making instant pudding; trace is the part where you put the pudding in the fridge to firm up. 

Add in fragrance oils and exfoliants

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Now's the part where you can really customize your soap. If you want scented soap, you'll add in 1.6 ounces of fragrance oil. I usually use orange oil because that's what we have on hand. If you want your soap to exfoliate, you can add in any number of exfoliants: oatmeal, dried herbs, and poppy seeds to name a few. 

Pour finished soap into your mold

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Once your mix-ins are thouroughly stirred, you can pour your soap into your molds. Using a waxy box is best because it prevents the soap from sticking too much. Above, I've used a quart size soy milk container, and it was just slightly too small to hold the whole batch. Cover the exposed area with a towel, and leave it all to sit for about 24 hours. 

Curing

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You're almost done! 24 hours after pouring your soap into the mold, you can remove it and cut into bars.

You'll then want to arrange the bars so that as much of their surface area is exposed to the air as possible. Each week, flip all the bars over so the other side gets exposed, and continue this for about four weeks. It seems like forever, but the soap needs time for the ph level to drop. If you use it right away, the harshness of the original lye mixture can irritate your skin. 

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That's it! Take a deep breath, order some lye, and get to it. You'll have plenty of bars ready in time for December's mad rush. 

Tagged with soap cold process

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