Making Hot Process Soap

A note about my soapmaking style

Herbal soap, vegan soap, castile soap, all-natural soap—call it any of those and it applies to my soapmaking style, which is from scratch with botanical ingredients. You can’t make soap without lye, although there’s no lye in the soap once saponification takes place. If someone says they made soap without lye, then they most likely used melt-and-pour, a pre-made soap, which means someone else had already used lye to make it. Soap is considered an all-natural product unless synthetics are added for fragrance or color. See About Hazelnut Grove Herbals for more info about my products.

When I made my first batch of soap back in 2001, I knew soapmaking would always be a part of my life. I built an herbal soap business and created more than 30 different formulas for moisturizing, soothing and healing soaps using unrefined, vegan carrier oils, organic botanicals and pure essential oils. I eventually sold the business in order to spend all my time with Lew during what became his last year. He has been gone 10 years now, and though I have not gone back into business I still make soap for my own use and for friends and family. I also enjoy teaching others, so here goes:

I’m looking to see what I have on hand today for carrier oils. My staples are olive, coconut, sweet almond and at least one nut butter. Today it’s shea butter, which I love for its nourishing and moisturizing qualities. I also love that it’s made by village women as a cottage industry in Africa. The women harvest nuts from the karite tree, and then render the butter over communal fires. They earn a living doing that when the butter is sold as fair trade. If fair trade means anything to you, check out Mountain Rose Herbs, where I buy (when I haven’t grown or wildcrafted) organic herbs and essential oils for my soaps and herbal products.

Note: It seems so strange that I am advocating plastic of any kind for any reason but it’s true, I am, when it comes to safety and hygiene. Yes, I can do it the primitive way but unless I absolutely must do it that way, I will use the easier and safer methods that I describe here.

Gather your supplies

Soapmaking is enjoyable and rewarding but things can go terribly wrong if you are distracted or you don’t have everything you need at hand. For hot-process soap you will need:

Crock pot

Stick blender

Large sheet of plastic to protect work surface. I have scraps of leftover 4-mil moisture barrier that works great. A vinyl table cloth would also work. Lay this down first thing on your counter or table, wherever you will be working. You may not realize you are splattering until later when you see the PERMANENT damage to your countertop or table. Plastic is the best protection from damage caused by lye (and essential oils, too).

Accurate digital scale, like a postal scale that you can buy at an office supply store

At least two liquid measuring cups, a 2-cup and 4-cup is best; plastic is safest (glass is heavy and slippery.)

A 2-qt plastic pitcher

Rubber spatula for stirring the lye and scraping the pan

Wax paper

Freezer paper

Protective gloves (vinyl, latex, etc) and shirt to cover arms

A large bottle of vinegar as an antidote in case of lye burn. Check the lid to make sure you can easily get into the bottle, then set it within reach.

And the ingredients:

Olive oil, 16 oz (Any olive oil will do; it does not have to be expensive, but it must be 100% olive, not a blend. Knowing the precise amounts of each oil in the formula is crucial when figuring out the lye.)

Coconut oil, 16 oz

Sweet almond oil 8 oz

Shea butter, 8 oz

2 oz essential oil (Some of the more affordable essential oils that also are great for skin care include lavender, patchouli, litsea cubeba and geranium.)

1 - 2 Tbs dried herb (I like to grind and sift lavender buds, which end up brownish in the soap, or use whole petals of calendula blossoms, which stay bright yellow.)

6.8 oz sodium hydroxide (lye) Used to be, you could buy it at the local hardware store. Not anymore, thanks to all the meth production out there because apparently lye is used in the manufacturing process. Nowadays you need to find a good soapmaking supply site for it.

13 oz water, either spring or distilled

This will make enough soap to fill one of my wooden molds, about 4 pounds, which makes 13 good size bars. This formula has 5% excess oil in the oil-to-base (lye) ratio to ensure a gentle soap.

Note: North America could have some beautiful vegetable oils but try getting any sunflower, soy, corn or canola that has not been gmo’d to death. The luxurious oils I use come from all around the world, which means expensive shipping unless I can find them locally. I use unrefined, organic and fair trade whenever possible… although if and when tshtf, I will take what I can get—might even be crying for some lard. I must say I’ve used soap made from tallow and it was nice. Bright white like you can’t get with vegetable oils, as well as silky smooth and very gentle. 

Before you start

The most crucial thing: Do not work with lye when children or pets are running around. Have no distractions, including company, and I’ll tell you why in a bit.

Mix the lye bath

The first thing you do is weigh and pour the water into the pitcher. Then, after donning vinyl or latex gloves, you gently scoop and weigh the lye in a dry measuring cup. Slowly pour the lye into the water, gently stirring with a rubber spatula as you go. Lye is extremely caustic (It dissolves gunk in drains!) The water gets flaming hot as soon as you stir i the lye (Oh and make sure to always add lye to water, NOT water to lye or you will have a volcano of sodium hydroxide on your hands.) Try not to breathe in the fumes. Once the lye is completely dissolved, set the pitcher somewhere safe where it can cool down, like on a ledge near an open window with absolutely no access for pets or children. A long time ago, I was cooling a pitcher of lye on the porch and got distracted when company arrived. We were sitting around the kitchen table gabbing like friends do, when a howl coming from the north porch shocked everyone. It was like nothing any of us had ever heard before. I suddenly remembered the lye and knew immediately what had happened, and it broke my heart. Thankfully my cat Willow was okay, although she disappeared under the house for a couple of days. She had a habit of dipping her paw into water and licking it off. That’s why I knew what had happened. Anyway, I was lucky because Willow was fine when she showed up again. It could have been so much worse. I vowed that nothing like that will ever happen again on my watch. So be careful. Ok, now that I’ve got you good and paranoid about making soap, I will lighten it up a bit and move on to the next step. Really, soapmaking is fun and rewarding. Just pay attention to safety and it will be fine.

Melt the carrier oils

So while the lye is cooling down, slowly melt the coconut oil and butters in the crock pot. I add a small amount of the olive oil to help this process. Turn off the heat, add remaining olive oil and let it finish cooling down while the lye is also cooling. The how-to books always say to use thermometers but that’s ridiculous. When the outside of the lye pitcher feels warm, not hot, it’s ready. The same with the oils. When they are just warm (you know, like a baby’s bottle) then they are ready.

As the carrier oils and lye bath are all cooling down, prepare the mold. Any kind of sturdy box will do, shaped like a square log or thereabouts, just large enough to hold about two quarts. I rub some shea butter or solid coconut oil onto the box interior, then line it with freezer paper with the paper side against the butter and the edges folded down outside the box. 

This is also a good time to weigh your essential oils if you plan on using any, and measure your powdered herb. Now everything is ready.

Blend, stir & cook

When both the oils and the lye bath have cooled down to warm, plug in the stick blender. Gently pour lye into oils while stirring with the stick blender without turning it on. Once the lye has been stirred into the oils, turn the blender on low and move it around gently until you reach trace. This usually happens within a couple of minutes. You’ll know it’s at the trace stage when the texture looks like a thin cake batter and it leaves a slight, raised ridge, or trace, across the top when you lift the stick blender. Can’t miss it.

As soon as your soap reaches the trace stage, stir in the essential oils if using any. Now turn the crock pot on LOW, cover and wait. Within a ½ hour you will notice the edge getting translucent. Gradually the entire pot of soap will turn translucent. That’s when it’s time to pull the plug and dump the soap into the mold. It will be very hot. Slam the mold against a sturdy table to help eliminate air bubbles. Set aside, cover loosely with a piece of wax paper. Hot process soap can be used as soon as it cools, although it becomes milder (lower pH) as it ages. I usually scrape the hardened soap from the crock pot with a butter knife and form it into a little ball.

If you’re interested in making additional soaps from scratch, learn about the qualities and chemical makeup of the carrier oils, including—especially—the saponification number. That number determines how much lye is needed to make a perfect soap. Mountain Rose Herbs is a great place to start because they offer an extensive selection of top quality organic herbs, essential oils and carrier oils, as well as excellent information on all the herbs and oils that they carry. I especially love their commitment to organic and fair trade, and their beautiful, informative little catalogs that even contain an occasional recipe for something like white chocolate candy or luscious body butter. 

Then, to actually formulate your own soap recipes check out this indispensable site: mms.lyecalculator.com