In honor of our 1000th post in October 2014, we are counting down our most popular posts of all time. Each has received over 100K hits, and some as high as 500K! This week, at #5, is Making Hot Process Soap in a Crock Pot!

I made famous soap today. Well, my soap isn’t famous, but the recipe is. Sort of. In a soapy kind of way.

It is a Hot Process Crock Pot, Oatmeal & Honey Castile soap recipe, known interchangeably as Kaleb’s Oatmeal & Honey Castile or Bunny’s Castile.

Soapers (people who make homemade soap) will understand what I just wrote, but for those normal folks out there who still haven’t nodded off, allow me to translate into English:

In (extreme) brief, there are two basic ways to make soap at home–cold process and hot process:

Cold Process: Combine oil(s) with a solution of water and sodium hydroxide (lye).

Hot Process: Combine oil(s) with a solution of water and sodium hydroxide (lye) and cook.

One method of hot process is the Crock Pot Method. Simply, you do the aforementioned cooking in a crock pot. A crock pot is desirable for this because it cooks slowly and evenly and is less likely to scorch.

Why one method over another? Many people do both, and some are strictly cp’ers only or hp’ers only. Cold process soaps tend to be smoother textured and take the fine details of a mold better than hot process. Hot process is favored by some because the cooking completes the saponification process and allows for a shorter cure time than cp soap. Some prefer the hp texture–rustic and handmade.

Finally, Castile soap is olive oil soap. That was easy. Well, not so fast. Castile also sometimes refers to soap made with vegetable oil only and no animal fat, especially if a high percentage of that oil is olive. Castile soap is mild, conditioning, and non-comedogenic. It takes a long time to cure (4-12 months), but once it is cured it makes a very hard, durable, and, in my opinion, superior bar.

Okay, back to the famous soap recipe. You can read all about it on the Latherings Forum, including the recipe itself and several soapers’ experiences with making it, including a few problems along the way. Suffice it to say that the word on soap street is that it’s great, and I had to try it. I am not quoting the recipe here because I think going to the forum with all its tips and caveats and anecdotal information is the best place to be when trying it out.

Here follows my first experience with this recipe:

These are the ingredients all spread out–olive oil, a little bit of castor oil, sodium hydroxide, water, oatmeal flour, & honey. That’s all it takes.

Gloves and Goggles! Don’t hurt yourself. Soap making is not rocket science, but it can be tricky and it has its safety issues. Here is one place to get up to speed on how to be safe. Here’s another.

I put the olive oil in the crock pot and added the castor oil to it.

The lye goes into the water, not the other way around or you may get a volcano/explosion. Visualize snow falling on a lake to remember. Stir to dissolve the lye completely.

Then the lye/water goes into the oils.

As I gave it a stir, the oil went from clear to opaque. The saponification process had begun.

I used an immersion blender to bring the mixture to trace. “Trace” is the point at which the mixture goes from liquid to pudding-y and a trace of the mixture will remain on the surface of the pudding for a bit when drizzled on the top. It took about 15 minutes. (Side note: If this were Cold Process, this would be the final step before adding the honey and oatmeal and pouring into the mold(s). But we are hot processing today, and so the story continues. . . )

I put on the cover and stirred occasionally.

After about 15-20 minutes it began to look like this:

I kept stirring periodically. It eventually went from foam on the edges to completely foamed-over:I stirred it back down and observed the separation phase. It looked like an oily, curdled soup. I let it
cook just a wee bit longer before turning off the heat and adding my honey and oatmeal.

In goes a slurry of 3 tablespoons of oat flour blended with a couple of tablespoons water (stir with fingers to make sure no lumps) and 3 tablespoons honey.

The mixture darkens a bit an thickens a little.

Now it was supposedly ready to mold. Never having HP’d before, I molded it up while it was still very liquidy. I am not sure how long I should have cooked it. Perhaps it was undercooked, perhaps it was overcooked. Perhaps the oil/lye ratio needed tweaking. Possibly the soap fairies were working a bit of mischief. All I know it was an oily, separated soup.

This wouldn’t do. I spooned it back out of the mold into the crock pot and did the only thing I could think of: I re-blended it with the immersion blender. And what do you know? The stuff set up immediately. A few short bursts with the blender and a bit of stirring to make sure it was homogenized and it went back in the mold.

Next day, it was solid enough to cut. I put it in my homemade Soap Guillotine:

It made 11 very thick, big bars. They will lighten up in color somewhat as they dry, but they are still probably darker than the perfect Bunny’s Castile, though I have never seen a photo of anyone else’s. If you have tried this and have a pic, I would love to see it and hear your comments on what I did wrong.

The soap was still oilier than I am used to in cold process. I would use this recipe again with caution. I think it is going to cure out very nicely, but it may take a while. Some people use their hot process soaps almost immediately, especially if they are not using olive oil, but I think this castile is going to need a good few months to reach its full potential. I can tell that it is already much milder than my cold process soaps at this point (day two)–the cold process soaps can be mildly caustic to the skin for weeks–this soap isn’t. For anyone trying out hot process (or cold process for that matter) for the first time, I would recommend starting with a recipe with no additives such as the honey and oatmeal in this case. They tend to complicate matters.
I must say, though, that this soap smells good enough to eat. It makes my mouth water every time I go near it.

This site has an excellent tutorial on how to line your soap molds. Basically, make a cardboard box the size of the inside of your mold and cover that with freezer paper. Voila, practically perfect mold liner.

This is also where I got the plan for the wooden log soap mold seen here. I like it a lot. It is the easiest thing in the world to unmold. Just take off the removable ends and lower the hinged sides.

Here are a couple of can’t miss hot process tutorials: Hot Process Soap Making by Gracefruit & Zensoaps Hot Process Double-Boiler method. And of course, my favorite spot for soapmaking in general is always Kathy Miller’s site.

One more thing. I picked up a crock pot at a thrift store for soap making only. If you get a second-hand one you might want to do this to make sure it is in working order.