Hot-Process Soap Making Adventures, with Recipes
Pros and Cons of Hot Process Soap Making
Faster cure time
Limited ability to make affects such as swirls, shapes, etc.
Harder, longer-lasting bars
Process takes longer due to cook time
If you sell soap, you can make product available for sale sooner
More essential oil needed, sometimes
To make soap, regardless of the process you're using, you need three basic ingredients; leave out one of these ingredients, and you don't have soap:
1. Oil or fat
3. Something to dissolve the lye in, usually water
There are a few different ways to make soap: Full-boil (the most "old-fashioned" method, and also the common commercial method), cold process, and hot process. I've been making cold process soap for a while now, but recently, I learned to make hot process soap.
In any process, a couple things happen in order to make the soap. Lye is dissolved in water. Oils and/or fats are melted and heated up. When the lye solution and the oils are around the same temperature, they are mixed. The raw soap mixture must be stirred and tended to until it reaches a state called trace, which describes a pudding-like consistency, and indicates that the ingredients are mixed properly.
The major difference between the methods is that in cold process soap making, the soap is poured into the mold after the raw soap mixture reaches a state called trace. And that's it for cold process soap - you're pretty much done! The raw soap "cooks" in the mold, continues saponifying (turning into soap) and 24-48 hours later you can cut it into bars.
But you can't use your cold process soap yet; you have to let it cure. Curing cold process soap can take three weeks to two months.
Kind of anti-climatic, don't you think?
In hot process soap making, rather than pouring the soap mixture into the mold at trace, the soap is instead poured into a cooking dish (not metal!) and cooked in the oven at 180-200 degrees Fahrenheit for up to four hours.
Soap that is made using the hot process method is fully saponified (totally soap!) after it hardens in the mold, and you only need to let it cure for a few days, just long enough for it to mellow out a bit and for what's left of the water to leave.
What to do if you get lye on your skin
Don't panic! You'll probably first notice a slight itching sensation. You will not suddenly have a gaping hole in your skin! This has been my experience every time I've gotten lye or raw soap on myself. Here's what you do:
- Douse the affected area with vinegar. This will neutralize the lye and turn it into a harmless salt.
- Rinse the affected area under cold running water.
- Wash the affected area with soap.
Soap Making Safety Precautions
Lye is sodium hydroxide, sometimes called caustic soda. It's the base agent in the soap making process that turns oil or fat into soap. When all's said and done, your bar of soap won't have any lye left in it, which is why it's safe to wash with soap.
Historically, lye was produced for soap-making by leaching it out of the ashes of burned-up hardwood firewood. Some people still do this today. The rest of us probably know lye as a popular drain cleaner and opener. You can purchase lye at any hardware store, and just about any grocery store. When making soap, you have to make sure that your lye product is 100% lye.
CAUTION: Lye is a chemical that will burn you if it comes in contact with your skin, blind you if it gets in your eyes, and likely kill you if you ingest it.
However, people handle lye literally everyday without killing or maiming themselves. They achieve this feat by wearing goggles, gloves, and long pants and sleeves, or other protective clothing like an apron. When working with lye, the trick is to avoid allowing your skin to come in contact with it. It's also not a bad idea to work with lye in a well-ventilated area, as the fumes that are released when lye is dissolved in water can smell bad and probably aren't something you want to breathe a lot of.
A great source for calculating soap recipes, including lye amounts.
"Another Lard-Based Soap"
Lard, 32 ounces
Coconut oil, 8 ounces
Crisco, 8 ounces
Castor oil, 3.2 ounces
Lye, 7 ounces
Water, 17 ounces
(3.2 pounds of oils)
"Vegan Soap (No Lard)"
Crisco, 16 ounces
Olive oil, 12 ounces
Coconut oil, 12 ounces
Castor oil, 2.4 ounces
Lye, 6 ounces
Water, 14 ounces
Now, on to the fun stuff!
The recipes! Here's three basic and very good soap recipes. I've used them all myself, and continue to use them or some slight variation of them. For each recipe, you should follow the intructions for cold process soap making. Once the soap has reached trace, you will cook the soap in the oven at 180-200 degrees.
Check on the soap and stir it regularly, every 20 minutes or so. When the soap has reached a state that is like mashed potatoes, where you can see that portions of it are beginning to become translucent, and the whole mass of soap is very thick and stiff, you should stir it thoroughly again. It usually takes my soap 1 to 2 hours to cook. You can now press it down into the mold and let it cool (I let it cool overnight). Once cool, the soap is ready to cut and cure for a few days, then it's ready to be used!
(All measurements are by weight, not fluid ounces.)
Coconut Oil, 12 ounces
Lard, 36 ounces
Lye, 6.8 ounces
Water, 16 ounces
(3 pounds of oils)
Using Kelp Powder in Hot Process Soap
For this soap adventure, I decided to experiment with kelp powder. I was looking to make a green bar of soap that I could scent with cedarwood essential oil. The kelp powder is green in the bag, so I reasoned it would make green (or at least greenish) soap - made sense to me!
Kelp powder is made from various types of algae, and is often eaten or added to food because it's a good source of iodine and vitamin E.
This batch of soap is one of my basic recipes, using lard, various vegetables oils, and castor oil (for extra bubbles in the lather). I decided to add the kelp powder at a rate of about 3% of my total oil weight. In this case, my total oils weighed 56 ounces (3.5 pounds) so I added 1.7 ounces of kelp powder. I added the kelp powder to the oils while they were warming up on the stove. I reasoned that it would be easier to mix the kelp powder directly into the oils, rather than into the raw soap once it had reached trace.
Everything seemed to be going just fine. The kelp powder mixed into the hot oils pretty nicely, making the mixture look green. I figured I was on my way to green soap!
I followed the basic soap making procedure from this point forward: I added my water and lye together, let the lye solution and the oils cool down to around 115 degrees Fahrenheit, then stirred them together.
During stirring, the raw soap continued to appear to be green. Cool! The soap mixture reached trace, and I added my cedarwood essential oil at a rate of 1 ounce per pound (3.5 ounces, in this case).
With visions of pretty green soap that smelled like a pine tree floating in my head, I poured the soap into my glass baking dish, shoved it into my 200 degree oven, and went about my business.
When I came to check on the soap 20 minutes later to give it a stir, I was quite surprised to find that the soap had turned white!
Using Chamomile Tea in Hot Process Soap
For this adventure, I decided to try out using tea in hot process soap. I've used teas as natural soap colorants in cold process soap before, but was always kind of disappointed that the final product didn't retain much of the aroma of the tea. At first the aroma is there a little bit, but quickly fades. I wondered if hot process soap made with tea leaves would still smell like the tea, or if, like in the cold process method, the aroma would be pretty much destroyed.
I chose chamomile tea for this experiment, since it's what I had in abundance.
Again, I used one of my basic soap recipes. I wore my gloves and goggles, mixed the lye and water, heated the fat and oils, and at the appropriate tempterature mixed the lye solution with the oils.
I stirred and stirred, and decided to add the chamomile tea leaves at trace. In went the tea leaves, and it looked like I was going to get a white bar of soap, flecked with little greenish-brown tea leaves. I figured it would be really pretty!
I didn't add any essential oils to this batch of soap, because the point was to determine if I could scent soap using tea leaves during the hot process method.
Into the oven went the soap mixture. I came back to it 20 minutes later to stir and take a look, and to my delight I was blasted with hot air from the oven that smelled just like a cup of chamomile tea! It seemed I was on my way to chamomile-scented soap, thanks to the tea leaves.
Well, ultimately I was right about the aroma of the tea sticking around in the hot process soap. I think it's because tea leaves are meant to be brewed in what's basically boiling water, which obviously isn't too hot to destroy the aroma.
What I hadn't counted on was the color of the soap - but when I really think about it, I should have known!
Using Cinnamon in Hot Process Soap to Make a Marble Affect
For this adventure, I decided to try to find out if I could make cool-looking multicolored soap using the hot process method, just like I could using cold process.
I've used cinnamon in soap before, so I figured that was a good place to start. I also decided to give kelp powder another try, figuring maybe I'd somehow done something wrong with it the first time around. I thought, hmm, brown and green marbled soap might be nice, and if the kelp powder leaves the soap white again, it'll still look good!
As always, I followed my standard lye solution-making procedure, heated my oils, and mixed everything together at the proper temperature. Again, I added the kelp powder to the hot oils before adding the lye solution, but this time I added the kelp powder at a rate of 5% of the total oil weight (remember that last time I added the kelp powder at 3% of the oils).
I held off adding the cinnamon. Because I wanted a multi-colored soap, and I only have one cooking dish that I use for soap-making, I had to cook the soap before I could add cinnamon to a portion of it.
The soap cooked for about 1 hour, looked like mashed potatoes, and was translucent in places.
The surprise this time was that the kelp powder turned the soap tan! Just my luck, considering I was planning on adding cinnamon to the soap, which makes soap brown.
I added my essential oils when I took the soap out of the oven.
I decided to continue on with my plan to add the cinnamon, despite the fact that I pretty much already had brown soap. I stirred the hot, cooked soap, and quickly separated out about 1/3 of it. I added cinnamon as slowly as I could, making sure I didn't overdo it. I'd say that I added cinnamon to about 1 pound of the soap, and added about 2 tablespoons of cinnamon.
I transferred the soap into the mold by first pressing down a layer of cinnamon-less soap, then the cinnamon soap, then finished of with the rest of the cinnamon-less soap.
The result turned out better than I thought it would!
Using Pumpkin Puree in Hot Process Soap
For this adventure, I wanted to make soap scented with orange essential oil, and I wanted to color the soap orange (very original, I know). I did a little looking around on the internet, and found some instructions for using pumpkin in soap. I figured that a pretty orange bar of soap that smelled like an orange would be a cool thing, and the pictures of the cold process soap made using pumpkin puree were just beautiful.
Like always, I used one of my basic soap recipes. I adhered to safety precautions for handling the lye, and started heating my oils while the lye solution cooled down.
I decided to add the pureed pumpkin to the oils right after they were melted and hot, but before I added the lye solution. I reasoned that it would be easier to add the pumpkin to the hot oils, rather than to the raw soap at trace.
This may have been a mistake, but I'll let you decide when you see the final product. Experimentation is the best way to learn, as far as I'm concerned!
When everything was at the right temperature, I added the lye solution to my oils and stirred. At trace, I added orange essential oil at a rate of 1 ounce per pound.
And to my surprise, I saw that the orange essential oil was already, well, orange!
Actually, the oil was kind of yellow-orange, and I thought, "Well, isn't that interesting." It looked as though I could have achieved an orange soap without the use of the pumpkin puree.
The raw soap before going into the oven was a deep orange, like the skin of a pumpkin. But the final product, after almost 2 hours of cooking, was a little different.