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!

Castile Soap

A couple of weeks ago, I made a Castile soap.

So, what the heck is Castile soap?

Traditionally, the oil used to make Castile soap consists entirely of olive oil. Oftentimes, soaps are made with a blend of oils. I tend to use a high percentage of olive oil in my soaps, but I also typically use coconut oil, palm oil, avocado oil, and/or shea butter in every batch, too.

My Castile soap

Castile soap in its purest form is simply olive oil, sodium hydroxide (lye), and water. That's it. No other oils, no fragrance, no colorants. This simple formulation creates a creamy, white bar with many reported benefits - it is gentle on the skin, naturally moisturizes, and supposedly helps combat acne, dry skin, eczema, and psoriasis.

So where did this "Queen of Soaps" come from? Castile soap enjoys a long, rich history. It was first made sometime around the 13th century in Castilla, a medieval kingdom in modern-day Spain named after the large number of castles in the region. Most soaps at the time were made with animal lard or tallow, but because Castilla had such a vast abundance of olive groves, they used olive oil instead. This luxurious soap quickly became a favorite among royalty and the wealthy in Europe. In fact, Louis XIV of France was so enamored of Castile soap that he demanded in 1688 that all Marseille soapmakers exclusively use olive oil in their soaps.

I've never used pure Castile soap before, and my interest was piqued after reading some discussions about it on a couple of soapmaking forums I belong to. I decided to take a stab at making my own. I did veer a bit from tradition, though - I am a total fragrance junkie and I just couldn't stand to leave it unscented. I kept things natural by using lavender and tea tree essential oils to lightly scent the soap. Honestly, I don't like tea tree on its own (I think it kinda smells like motor oil) but it is wonderful when used sparingly with other essential oils. Lavender and tea tree is one of my new favorites.

Sadly, this soap is nowhere near ready to use, so I must exercise patience. I normally let my soaps cure for about six weeks before I use them. (During the curing time, the water in the soap evaporates, creating a harder, longer-lasting bar. The soap also becomes milder as it cures.) Castile soap can be used after 4-6 weeks, but it benefits greatly from a much longer cure time. Ideally, Castile soap should be cured for at least four months, and it is even better after a year.

It seems like people either love Castile soap or hate it. I've heard some folks say that they don't care for it because it can feel slimy. I am told not to expect a fluffy, bubbly lather - Castile's bubbles are small, creamy, and slippery. Other folks love this about Castile, praising how it leaves their skin feeling soft and nourished. I hear more positives than negatives about Castile, so I have high hopes and I am excited to try it. I guess I'll just have to wait a few months to see if this soap lives up to my expectations!

Until next time ...