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Hot-Process Soap Making Adventures (With Recipes)

Adventures in hot-process soap making

Adventures in hot-process soap making

Making Soap

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:

  • Oil or fat
  • Lye
  • 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 of 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 and 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.

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

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 every day 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.

This is 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 Recipes

The recipes! Here are 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 instructions 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.)

Simple Soap

  • Coconut Oil, 12 ounces
  • Lard, 36 ounces
  • Lye, 6.8 ounces
  • Water, 16 ounces
  • (3 pounds of oils)
Kelp powder - I swear it's green!

Kelp powder - I swear it's green!

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 vegetable 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!

Guess I'll have to find another way to make green soap! This kelp powder recipe turned out white-grey, with brownish flecks. David decided I should call it "Alpine Forest Soap" - smells like a pine forest, looks like winter.

Guess I'll have to find another way to make green soap! This kelp powder recipe turned out white-grey, with brownish flecks. David decided I should call it "Alpine Forest Soap" - smells like a pine forest, looks like winter.

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 temperature, 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!

The chamomile tea soap came out a tan color, which I didn't love at first - but it's grown on me! And two weeks later, I'm happy to report that the soap smells just as strongly of chamomile tea as it did the morning I cut it.

The chamomile tea soap came out a tan color, which I didn't love at first - but it's grown on me! And two weeks later, I'm happy to report that the soap smells just as strongly of chamomile tea as it did the morning I cut it.

Using Cinnamon in Hot-Process Soap to Make a Marble Effect

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 one 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 one pound of the soap and added about two 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 off with the rest of the cinnamon-less soap.

The result turned out better than I thought it would!

Turned out pretty nice! I was surprised at how the kelp powder colored the soap differently this time. It must be because I used more of it. And I was right about the marble affect being possible with hot process.

Turned out pretty nice! I was surprised at how the kelp powder colored the soap differently this time. It must be because I used more of it. And I was right about the marble affect being possible with hot process.

Pumpkin puree.

Pumpkin puree.

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 one 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 two hours of cooking, was a little different.

 It's pretty!! Somehow, it seems that the pumpkin color got cooked right out of the soap. Or, maybe I'm wrong about that, and this is what cooked pumpkin in soap looks like. Maybe, without the pumpkin, the orange oil would have turned the soap yellow

It's pretty!! Somehow, it seems that the pumpkin color got cooked right out of the soap. Or, maybe I'm wrong about that, and this is what cooked pumpkin in soap looks like. Maybe, without the pumpkin, the orange oil would have turned the soap yellow


GDPR Consent Management Solutions for Publishers, Advertisers & Agencies. on August 06, 2018:

HONselect - Eisenmenger Complex

Ana on May 13, 2018:

I know I came across your article a bit late. I am a soaper. I do only cold process but would like to start making rustic looking hot process soap especially salt bars. I enjoyed

reading your article and greatly appreciate you sharing the information so freely with us.

I just wanted to give my two cents on the safety subject. When you get lye on skin you should never put anything acidic such as vinegar to counteract/ neutralize the caustic effect, because an acid-base reaction will take place and it is quiet exothermic (meaning releases heat). So you may end up with a heat burn rather than chemical burn. The correct procedure in any chemistry lab is simply rinse, wash with mild soap, then rinse for at least 15 minutes under running water. In the lab we are not allowed to wear gloves( safety hazard for us, but for soapers gloves are recommended) and we deal with substances that are far more caustic than NaOH, and this is a standard procedure for us. You may not have noticed this due to small effected areas but if someone spills a good amount of NaOH solution on themselves, they might get a serious burn if try to neutralize with acid.

Another tip for soapers, if NaOH is accidentally spilled on the floor of any other surface, generously pour baking soda on top until fully absorbed, then swip, do not try to absorb using paper towels.

Rachel Koski Nielsen (author) from Pennsylvania to Minnesota on March 05, 2016:

The joke has been made once or twice ;)

Suzie from Carson City on May 15, 2015:

Congratulations on your HOTD! I have lost count of how many times I have tried to suggest to myself that I try my hand at making soap or candles or both! Seriously, because I love nice soaps (especially if they are scented naturally) and I also love candles. As you know, they're so expensive to buy.

This is such a useful and creative craft. Thanks so much for sharing these complete & easy to follow directions. Maybe you have been the one to finally encourage me to go for it!! ...UP+++ Peace, Paula

Candle Reviews on May 15, 2015:

I love the idea of making my own soap. Thanks for sharing.

Natalie from Miami, FL on May 15, 2015:

Very interesting article. Soap making is definitely on my "Things to Try" list.

Nicole Grizzle from Georgia on May 15, 2015:

This look really interesting, especially the vegan soap recipe. I'll have to try it sometime. Congrats on the HOTD!

The Gutter Monkey on May 15, 2015:

Congrats on Hub of the Day.

I bet people are always asking if you know Tyler Durden.

Thelma Alberts from Germany on May 15, 2015:

Congratulations on the HOTD! I enjoyed reading this fascinating and informative creation of soaps. Thanks for sharing. Well done.

RTalloni on May 15, 2015:

Congratulations on your Hub of the Day award for this neat soap making hub. Enjoyed your approach to the topic and the details you shared in your processes. I hope to return to this for another read when I can make plans to give this a try.

Deborah Demander from First Wyoming, then THE WORLD on May 15, 2015:

Fascinating and informative. I love your descriptions of different experiments with soaps, scents and colors. Thanks for writing.


Kristen Howe from Northeast Ohio on May 15, 2015:

Rachel, congrats on HOTD! This is an awesome and clever ideas to make your own soap at home. Voted up!

Jennie Hennesay from Lubbock TX on May 15, 2015:

I love the rush of trial an error scenting and coloring soaps. I've never done very much hot process except for a "mechanic" soap I made for cutting grease. If you want a green soap, parsley is the only herb I've found that stays green in cold process soap. I haven't tried it in hot process.

Venkatachari M from Hyderabad, India on May 15, 2015:

Great thing to know. It seems you are genius in this soap making. Wonderful hub. So detailed and awesome knowledge. Particularly those vegan soaps are funny to make, I hope.

Voted up and awesome.

Rota on May 15, 2015:

LOVE this hub! Thanks for including a vegan soap recipe..and pumpkin soap? What can I say? Marvellous!

poetryman6969 on April 30, 2015:

Pumpkin soap! You must live a fascinating life. It's good to know that lye is not instantaneously fatal. Voted up.

Lady Summerset from Willingboro, New Jersey on October 22, 2014:

Wonderful Hub! I've been flirting with the idea of making soap for years...However, the idea of using lye and having a grandchild living with us has constantly veered me away from trying it! I love the handiwork of those who are able to produce such lovely soaps with swirls, colors, and intoxicating fragrances!

Rebecca Be from Lincoln, Nebraska on October 22, 2014:

I have a friend that makes soap and sells it. The soap is so much nicer than what you get in a regular retail store. I did try to visit your Etsy store as you requested at the end of the hub. Once there I read it is closed until April.

Author Victoria Sheffield from Georgia on October 22, 2014:

I love making my own soap!

Dolores Monet from East Coast, United States on October 22, 2014:

I love the pumpkin soap - it's so beautiful! I haven't made soap for a year or so and am thinking about making some. Thought about doing the hot process again. I really like the chamomile idea.

SEXYLADYDEE from Upstate NY on September 25, 2014:

Great HUB! As a fellow soap maker I like the way you share your different experiences. I have had great success with all natural ingredients. My pumpkin soap sold well but one bar I had almost a year later started to mold. That worried me. Keep sharing. Voted up and useful. Come by and see my Soapmaking Hub. Dee

Susette Horspool from Pasadena CA on August 18, 2014:

This is cool. I just signed on to help a soap maker with her website publicity and then ran into your hub. I'm going to book it for future reference, if that's ok with you. Voted up.

Tori Canonge from North Carolina on June 02, 2014:

This hub is very well written! I have always wanted to make my own soap. The cinnamon and pumpkin soaps are especially appealing to me. Thanks to your directions, I feel like I could do this successfully!

Rachel Koski Nielsen (author) from Pennsylvania to Minnesota on February 24, 2013:

Homerevisor- thanks for your comment!

Rosie- thanks for commenting! Glad you enjoyed the hub, and I do hope you will try making soap some time. Very rewarding! I rarely experience anything with the fumes, but it's not a bad idea to work in a vetilatex space, prepare to open a windiw, or just hold your shirt over your mouth and nose. The goggles and gloves are vital though!

Audrey Surma from Virginia on February 02, 2013:

Voted up and useful! Very impressive hub, loaded with information. I've always wanted to make my own soap and should I find time, I will be referring back to your hub. I'm a little nervous about using lye inside my home - fear of fumes. Your precautions are appreciated. Awesome hub!

Home Revisor from New Jersey on January 29, 2013:

Awesome article, very detailed and a really interesting idea. Will definitely have to try this out at home! Looking forward to Following you and reading some more of your articles :)

Praveen P.V. Nair from Trivandrum on November 15, 2012:

Thanks rachel. Pls keep in touch with my hubs also. :))))

Rachel Koski Nielsen (author) from Pennsylvania to Minnesota on November 14, 2012:

Hi Lifetips, thanks for the comment! Glad you enjoyed the hub :)

Praveen P.V. Nair from Trivandrum on November 13, 2012:

Hi rachel, the way in which you explained this article is great and hats off for that and also pictures are great. Keep in touch. Voted up and awesome

Rachel Koski Nielsen (author) from Pennsylvania to Minnesota on September 23, 2012:

Hi Gail - Thanks for the comment! I'm really glad my hubs have been useful to you in your own soap making adventures. And you're right - without lye, it's just not soap! Just wear your gloves and goggles and you'll be plenty safe from lye burns :) Take care!

Gail Meyers from Johnson County, Kansas on September 17, 2012:

I'm just beginning my soap making adventures and I appreciate your hubs! I love the pumpkin idea. I think a lot of people are put off by the lye, but without lye it's not soap!

Rachel Koski Nielsen (author) from Pennsylvania to Minnesota on September 17, 2012:

diyomarpandan - Oh cool, so you have pure glycerin! Sounds like you could easily make liquid soap with it. I would look into mixing it with washing soda (sodium cardonate). I think there are a couple popular brands that make it.

I know that some soap-makers add glycerin to their homemade soaps, because the all-vegetable recipes that they use sometimes don't have enough saturated fats in the oils, and therefore the soap doesn't have as much glycerin as animal fat soaps do. (Which is why I like lard and tallow soaps best)

As far as melting bar soap from the store, maybe you didn't use enough soap for the amount of glycerin? That may be why it's not very bubbly. Try cutting back on the amount of glycerin and using more melted bar soap. :)

Rachel Koski Nielsen (author) from Pennsylvania to Minnesota on September 17, 2012:

diyomarpandan - Thanks for commenting :) Well, all soap has glycerin in it. Glycerine is produced with lye reacts with fat (triglycerides). So I'm not totally sure what you mean, but I think you're referring to "melt and pour" soap? Like, when you buy a block of soap base and melt it down, add some smelly stuff and herbs to it, and pour it in the mold? I've never made soap that way, personally. I think the soap bases often have chemicals and additives in them that I'm not interested in. Plus, when I want to learn to do something I go to the oldest possible method that I can find, haha. If you want a bubblier soap, I would suggest using one of the recipes that I provided that includes castor and/or coconut oil. Both make nice bubbles. But then again, plain old lard soap is pretty perfect on its on, as far as I'm concerned. Take care! And if you have any questions, feel free to contact me directly :)

Rachel Koski Nielsen (author) from Pennsylvania to Minnesota on September 17, 2012:

Dirt Farmer - Thanks for dropping in, Jill, it's always nice to see a comment from you :) I like the pumpkin soap too, just wish it had come out a little more orange!

Jill Spencer from United States on September 17, 2012:

Pumpkin soap. What a great idea! Perfect for an autumn gift basket, guest bathroom or just for fun. Another really good hub, Rachel. Enjoyed it and shared it. (:

Rachel Koski Nielsen (author) from Pennsylvania to Minnesota on September 17, 2012:

Carol - Thanks for commenting and sharing! You know, the lye really isn't all that scary. I just feel that I have to tell folks that it is caustic if I'm going to write about soap-making. I wear sunglasses and rubber cleaning gloves when I handle it. It really becomes a nonissue after you make soap a couple of times. And honestly, I don't think it's any more dangerous than what's under the hood of a car, or the hot oil that we cook with, or the chemicals that we spray all over our lawns. But I guess it's not for everyone, and that's okay :)

Rachel Koski Nielsen (author) from Pennsylvania to Minnesota on September 17, 2012:

Hi Bill! I get some views, yes. Not a ton, but I do pretty well for a "newbie," I suppose. Some people are actually offended that I write about making soap because it involved lye (and I don't mean you, Carol! I'm referring to a couple of people who commented on my soap HOTD hub!) So who can say? I like back to basics, and I write what I know :) Thanks for stopping in!

carol stanley from Arizona on September 17, 2012:

I think of soap everyday..However, I have to admit the lye part has sort of kept me away. I like the idea of having soap scented in favorite flavors. Thanks for sharing..So I am voting up and sharing.

Bill Holland from Olympia, WA on September 17, 2012:

I'm curious if you are getting a lot of views with these how-to hubs.....I would think that more and more people will want hubs like this one. Great job as always Rachel!