Castile Soap Revisited

Almost a year and a half ago, I made my first batch of Castile soap. Traditionally, Castile is made with only one oil - olive. Just olive oil, lye, and water. This simple recipe creates a creamy, luxurious bar of soap.

Castile soap benefits from a long cure. Typical soaps are ready to go after about 4-6 weeks, although I think they get better, too, with age. As you can see from this post about my Castile's progress over weeks and months, I wasn't quite sure what to think of it at first. The soap had to sit for quite a while before I started liking it. I wasn't particularly impressed at weeks 6 and 12 - the lather was minimal and slimy. I started to notice a change in the lather around week 18, though. By then, the lather seemed less slippery and a bit more bubbly. After six months, it was even better. And now that the batch is over a year old, it is fantastic. Castile may never have big, fluffy bubbles, but the lather does become creamy and dense over time. (I like to use a  mesh shower poof to help kick up a nice lather.)

Swirling mica/oil drizzled on top.

Because Castile requires a very long cure time and I have only a few bars left from the last batch, I figured that I better make more now so it can sit for a while.

I made this batch with a classic olive oil, lye, distilled water, and essential oils of lavender and peppermint. (I have a difficult time leaving things unscented.) And because the soap recipe is so simple, I decided to jazz things up by attempting a technique that I have been wanting to try for a while now - mica oil swirled tops. To make mica oil swirls, mica is mixed with a small amount of oil, drizzled over the soap, and then swirled. The oil saponifies along with the rest of the soap, leaving the shimmery mica swirls behind.

 Here is a video I made of the process:


I had some challenges with this batch. As you can see in the video, the soap turned out really soft. Even after sitting for a week, it was like prying room-temperature butter away from the mold. I tore the side of one bar trying to slide the side away, and bits of the soap stuck to the bottom. When I made my first batch of Castile, I used a log mold. The soap was soft when I went to cut it, but I don't remember it being as soft as this new batch was.

Could be a couple of things. First, I probably need to do a much steeper water discount with Castile batches. I usually use full water in my regular recipes, with the water being 38% of the oil weight (which gives me a lye concentration of about 27%). For the Castile, I bumped the water down to 33% of the water weight - which, honestly, isn't much - and I think I need to bump it down even more. My first batch did okay at these ratios, although it was a bit soft initially. I don't know why this batch seemed so much more softer. Maybe it didn't gel in the slab mold? I'm not sure that my first batch of Castile gelled, though. I didn't see either batch gel. (I usually peek after insulating and often catch my soap gelling. It's so cool-looking!) Methinks the water is the problem, though. I've been doing some reading and it seems that a lye concentration that's closer to 40%-50% would be better. Regardless, it should still cure into nice, hard bars, especially since I'm going to let it sit for 6-12 months!

I also wonder if the additional oil for my mica swirls had anything to do with it. Probably not, since I used so little oil to mix the micas. I doubt it was enough to dramatically alter the soap.

Overall, I am happy with how this batch turned out, although I wish that my swirls were prettier. I still need some practice with that. But I do like how the oil/mica mixture worked out, leaving the shimmery mica behind on top. It's such a fun and easy way to dress up bars! The mica swirls can give lots of fun color to a bar, or give some personality to a batch that discolors dark brown due to the fragrance oil.


I'm glad that I have another batch of Castile waiting for me! It will still take some time to get through my last batch. And I've got other soaps besides the Castile to use, too! It's always so fun to go into my soap room and pick out a new bar!