February 18, 2015

Making Soap with Goat Milk: Hot Process

This is Part Three in my series on making goat milk soap. You'll find Part One and Part Two here.

In Part One, I talked about lye safety, soapmaking equipment, and how I get ready to make soap. In Part Two I made a batch of cold process soap.

Cold process and hot process begin the same way; in fact, you'd do everything in Part Two up to the point of pouring the soap into the mold. That's where this post begins.

First, the legal stuff:


These are the safety procedures I use.
Please note that I am not responsible for accidents;
this post is for educational purposes only.

For cold process (CP), the raw soap is poured into a mold and left for 24 hours to saponify (this is the chemical reaction), then cut and cured for 6 weeks. Hot process soap (HP) is poured into a slow cooker and cooked, then put in a mold. HP soap is "done" after the cook, saponification has already happened, and as soon as it is hard enough it is removed from the mold and cut; it's ready to use at that point. The longer you let it cure, the harder it will be and the longer it will last, but if you're impatient hot process might be the way to go.

What additional equipment is needed to make hot process soap? A slow cooker. That's it. You might be able to find an older model at a thrift store or yard sale. I looked for quite some time but didn't find one, so I bought a new Crock-Pot (affiliate link) for my kitchen and dedicated my old one to soapmaking.

All right, let's begin at the end of Part Two when the soap reaches "trace" - the raw soap thickens and turns opaque. Instead of pouring it into a prepared mold, I pour it into my old slow cooker. I plug it in, turn it on and set it on Low, put the top on and leave it alone.

I check on it every 15 minutes or so. As the soap cooks, it climbs up the sides of the slow cooker and sort of folds over on itself.

More and more of the cooked soap is visible, and the uncooked center gets smaller and smaller.

Eventually there's no smooth, uncooked soap left in the middle. This takes about an hour. I stirred it up before taking the photo below.

The consistency is rather like waxy mashed potatoes. This is the time to add fragrance or essential oils if you're going to scent your soap.

The soap is spooned into the mold. There is no "pouring" of this soap, it has to be scooped up and plopped in the mold. Once it's all in, I do my best to pack it down and get rid of air bubbles. I gently bang the mold a few times on the table to help settle it in place. Any soap that was left in the slow cooker, on the spoon, or dropped on the top of the workbench has dried immediately. It's a good idea to cover your workspace with newspaper before this step.

Notice that the top of the soap in the mold doesn't have any resemblance to "smooth". It sets up really fast; there is no way to smooth it out.

As soon as the log of soap is hard enough, it can be removed from the mold and cut into bars. If you don't want this interesting-looking top on your bars, you'll need to cut the top off when you cut your bars.

It looks very different from cold processed soap. It's much darker in color and the top is crumbly-looking. There are color variations in the body of the soap. I think it looks rustic and it's beautiful in its own way.

It's unmolded and cut into bars in the same way as cold process; we'll do that in the next post. Hot process soap doesn't need to be cured for as long as cold process soap. It's ready to use right away, as soon as it's cut into bars, but it will be harder and longer-lasting if it cures for at least a week.

I prefer not to go through this extra step and I usually stick to the cold process method, but hot process does have its place if you're in a hurry. Which method would you prefer?

In this series:
Making Soap with Goat Milk: Safety, Equipment, and Getting Ready
Making Soap with Goat Milk: Cold Process
Making Soap with Goat Milk: Hot Process
Making Soap with Goat Milk: Unmolding, Cutting and Curing
Making Soap with Goat Milk: Random Thoughts and a Recipe

This post has been shared at some of my favorite blog hops.


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  1. Our plan is to do cold process. Kathi, we plan to use goat milk, but I don't want to freeze it or use ice water. I plan to use a sink of cold water with cold milk. Will this do anything besides make the soap a darker color? Will it keep affect the saponification process? I appreciate these posts. They have become part of my research.


  2. Kathi at Oak Hill Homestead8:28 PM

    It will work fine, Fern. You'll have brown soap but it will be soap. I've always frozen the milk before making the soap but if someone used water, they wouldn't freeze it first. Feel free to write me if you have any questions, ok?

  3. I have not tried this method. It does make an interesting looking soap.
    Great series!

  4. Kathi at Oak Hill Homestead6:08 AM

    Thank you, Sandra. It's sure different-looking, isn't it?

  5. I think the cold process is how I'll do it, I don't like extra steps! This is so helpful for me, thank you so much!

  6. Kathi at Oak Hill Homestead5:57 PM

    You're welcome, Jennifer. I agree with you, I prefer to do it the quick and easy way. :-)

  7. I bought a book about soap-making once with the intention of learning to do it, but I think the thought of lye made me nervous and I haven't thought about it since! I love all of your pictures. They're very helpful. And aren't crock-pots great for everything??? LOL Stopping by from misAdventures bloghop. Have a great week!

  8. Kathi at Oak Hill Homestead6:37 PM

    Hi, Quirky Homemaker. I hope you'll have the courage to try it someday if you really want to. Have a blessed week.

  9. Kathi at Oak Hill Homestead6:37 PM

    Hi, Quirky Homemaker. I hope you'll have the courage to try it someday if you really want to. Have a blessed week.

  10. Great post again. When I made soap it was via the cold pressed method but the woman who I got the recipe from said that I could use it in 3 weeks. I think if I was in a hurry I would use the hot process and it sort of looks cute with the rough top. Could I use my slow cooker for food after I used it for soap if I cleaned it well??? Thanks for linking up at Good Morning Mondays. Blessings

  11. Kathi at Oak Hill Homestead11:08 PM

    Terri, I've read of many people who use their crockpot for food as well as for soapmaking. When the soap is finished, it's "soap" and all the lye should have been incorporated. That said, I've dedicated my old crockpot to soapmaking only.

  12. Thanks for that. when I was telling my husband about it, he said "you don't use it for food again do you??" so I guess I might need another one. Blessings

  13. Kathi at Oak Hill Homestead6:00 AM

    I feel the same way your husband does, Terri. There are folks that use their soapmaking tools for food prep too, but I don't. :-)

  14. PINNED. Beautiful tutorial also. Best wishes, Linda at Crafts a la Mode

  15. Kathi at Oak Hill Homestead4:56 PM

    Thank you, Linda!

  16. You are so making me want to try making soap. Seriously, with each new post, I am like, hey I might be able to do this! Thank you for being part of the (mis)Adventures Monday Blog Hop!

  17. Kathi at Oak Hill Homestead7:43 AM

    Hmm, Mindie, maybe you should give it a try. ;-)

  18. Kathi at Oak Hill Homestead7:43 AM

    Hmm, Mindie, maybe you should give it a try. ;-)


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