Tuesday, March 27, 2012

How I make cold process soap

I talk about making soap so much. No really, I talk about it a lot. Usually I end up being asked, "How do you make soap exactly??" Either my friends are just being nice and humoring me through conversation, or a lot of people are really interested to know how it's done! So I thought I'd put together a short little post covering exactly how I make cold process soap, aka lye soap or handmade soap. 

A few weeks ago I walked my mom through making a batch of soap, then a day or two later turned her loose to make her own, while I stood by for questions, to take pictures, and omg wait don't do thaaaattt!! Here are some photos and basic descriptions of what's going on in a sort of step-by-step process.

The Recipe:

Most CP (cold process) soap recipes have a basic recipe of lye+water (lye solution), solid oils (that need to be melted down) and liquid oils. More advanced and luxurious recipes can include some natural butters (cocoa, shea), herbs, exfoliants and extracts as well. 

Here is the basic "Lots of Lather" recipe we used for this batch of soap, from a lye calculator app I got for my iPhone that came with a few preformulated recipes. All measurements in this and other soap recipes are by weight, not by volume.

In this recipe, our solid oils are Coconut and Palm, the liquids are Olive and Castor, and we substituted plain water for actual brewed tea (made with distilled water). Below are all our ingredients and the equipment we used: oils, lye, tea, bowls, measuring cups, digital scale and thermometer (not pictured), spatulas, fragrance oil, and stick blender (also not pictured). 

Safety first!:

It's important when working with lye to take safety precautions like wearing rubber or latex gloves and protecting your eyes from splashes. Long sleeves, pants, and shoes are also recommended. Always use utensils and containers you have set aside specifically for CP soapmaking, do not use them for food or cooking after they've been used for soaping. Do not use metal containers or utensils, heat safe glass and plastic are best. I like to use paint mixing buckets. They come in a variety of sizes and you can get them for less than two dollars each at Ace Hardware or Wal-Mart. 

my mom, ready to soap!
Also, keep kids and pets out of your workspace!

Make sure you are working in a well ventilated area. I usually just stay near the open window in our kitchen, and stand at arm's length from the lye I am working with to avoid breathing it in.

Lye Solution: 

Carefully measure out the amount of lye listed in your recipe. It's important to measure this out exactly as it can change the result of your batch. Measure out your distilled water (in our case, brewed tea, and I have also used coffee in another batch too!!). Slowly pour the lye into the water, not the water into the lye!! Unless you like corrosive explosions.... Mix with a long spatula or spoon until all the lye has dissolved. 

Now, this solution gets really HOT while it is being mixed. 

After it's mixed, you'll want to set it to the side to cool down to at least below 130 degrees. I put mine in the windowsill, again to avoid fumes, and recently have started setting the container inside another larger paint bucket full of ice water to speed along the cooling process. 


While your lye solution is cooling, start measuring out the solid oils in your recipe. You will need to melt this down to a liquid form, either in the microwave or a double boiler. (Some oils or butters will only melt properly in a double boiler slowly over very low heat, but the ones I used here melt just fine in the microwave.)

Then measure out your liquid oils, very simple. I weigh them on my scale directly in the larger bowl I will be using to mix up the whole batch in the end to cut back on cleanup. Oils are a pain to wash out!

Go ahead and measure out the fragrance or natural essential oils you will be using to scent your batch of soap, as well as any colorants or other additives. We used a Chai Tea fragrance oil at around 1.8 ounces, and no dyes as the tea acted as it's own natural colorant to the soap.

Now it's a waiting game, keeping a check on the temperature of your lye solution and heated oils. You'll want to combine them when they are both under at least 130 degrees (F). The cooler these mixtures are when you combine them, the less the chances of it acting up (superheating, thickening up too much, etc) as you are mixing the batch. It's a learning process for sure, figuring out the temperatures that work well for different recipes, but right now I have started combining my two mixtures at closer to 100 degrees (F) for easier pouring and smoother finished soap.

Mixing your batch for real:

Once you've reached the desired temperatures, mix your melted solid oils with your liquid oils in your larger bowl, then slowly pour in the lye solution, being careful not to splash it everywhere. Plug in your stick blender (if you think you are going to stir this up by hand, rethink---it can take in excess of two hours to mix fully---and my stick blender only cost me eleven bucks on Amazon.com!), set to lowest setting, and "pulse" blend the mixture until it reaches what is called trace. Be sure the mixer is reaching all the way to the bottom of the bowl while you are  mixing, and be careful not to lift it in and out of the mixture too much because you will get a lot of air bubbles.

Simply put, trace is the stage at which your mixture is completely incorporated with no oils floating near the top, and when you lift your blender out of the bowl and shake it off, the droplets should leave a pattern on the top of the mixture. Kind of like a thin pudding. 

It's really easy to over mix the batch, so be careful. It literally takes only a few seconds (10-20) of pulsing with the stick blender to reach trace. If you mix too much, your batch will be very very thick and hard to pour evenly into molds. 

Pour it up!:

Now you are ready to pour your soap into molds. 

You can use molds made specifically for soap, or you can make your own with household products like pvc pipe (upright and capped securely on the bottom end), or even shoeboxes lined well with parchment paper. 

Pour from your bowl into the mold(s) and be sure to scrape the sides and bottom of the bowl with a spatula too, to get it all in there! You can lightly tap or shake your mold to make sure it all settles in well too, especially if your mixture is fairly thick. 

You want to keep the soap well insulated while it is setting up. Cover with plastic wrap and then again with a towel over the top. With this particular mold I also put a towel underneath because of all the individual cavities, to keep air flow from getting in there and cooling it down too quickly. 

The insulating is to ensure that your soap will go through the saponification process, or gel phase, where it superheats and... well, turns into soap! Here is a picture of our batch after it had been covered for a couple of hours, in almost full gel phase. 

It's not a huge big deal if your soap doesn't "gel." It will still turn out just fine, although it can develop a little bit of a powdery coating on the outside, called soda ash, from cooling too quickly. It can be easily cleaned off or shaped up by scraping with a knife, soap cutter or vegetable peeler. 

Let the soap stay in the molds covered and insulated for at least 24 hours before you remove it. 

Here are our finished soaps. We had a little extra mixture that we put into a separate mold that didn't superheat (gel), and you can see the ash on those in the picture (the round ones). The soaps that gelled turned out a darker color as well. CP soaps will need to "cure" for 4-6 weeks before they are ready to sell or use. During this time, the soaps will release moisture (and lye) and harden up a good bit. 

and they smell amazing!!

While the soap is curing, you may even find that your fragrances or colorants fade or even change completely. Most soap supply websites do intensive testing on their products and will note problems or changes to expect individually on each fragrance and colorant. 

And that, my friends, is how soap is made! 

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