The Fugue

Previously on The Fugue, I told you how to make Castile Soap in 5 Minutes. Having been through the process a few more times since then, I have a couple of addendums.

First, on measurements. If you're at all serious about making soap you either need to do large batches or get a scale with 1 gram precision. With my old scale (which had 5 gram precision) I had hits and misses with the size of batch that I like. i.e. 1–2 bars worth. Most recipes you find on the internet are what I would deem "large batches", and are really more like medium batches. But when you're trying to nail down the perfect recipe, making 5–10 bars of soap is wasteful, or at least a really really slow way to go about it.

Second, on ingredients. Pure castile soap is great, but has to be treated with respect or it can get really slimy. Coconut Oil is easy to obtain and adds hardness and lather. Lard or tallow is cheap and also hardens the bar. So I've been doing 6 parts olive, 2–3 parts tallow or lard, and 1–2 parts coconut oil and others (like cocoa butter). I calculate the lye then use 2 parts liquid for 1 part lye (by volume). I like to use milk instead of water, because I made this one bar with milk and the caramelized sugars (from the lye heating up when mixed with the milk) made a bar that smelled divine.

Third, on measuring again. For the size of batch I'm doing (on the order of 80 grams fat) I figured out that measurement error gives me ±2%. So I round the lye and fats (check the total weight so the measurement errors don't compound), then add 2g (a bit over 2%) of fat. So I know I'm between just under 1% superfat and 5% superfat, which is acceptable. I don't want more than 5% but of course you really don't want less than 0%. The same idea would apply with a 5g precision scale, but you'd have to be doing batches about 5 times as large (I think).

Fourth, on temperature. I don't measure temperatures. I aim for "warm to the touch" on the outside of each container before bringing them together. Rather than wait for the lye to cool down to "warm", I start with really cold liquid, sometimes in the form of one or two ice cubes. The ice cubes melt, and the final temperature is much closer to the target and so there's much less waiting. Obviously, if you're using more solid fats you want the temperature to be above their melting points until you get a good mixture.

Which brings us to the final point, mixing and molding. I am more than ever convinced that shaking in a water bottle (or large soda bottle) is an excellent way to go. It is safe, convenient, cheap, and fast. However, it's not such a great mold. It will work as a mold, but it will take that much longer to set up (evaporate water). Usually you demold after 1–2 days, but getting cheese-consistency soap out of a water bottle without marring it is an exercise in futility. So now I use paper cups as molds, and I pour the soap in from the water bottle when it reaches trace. As a bonus, you can clean out the water bottle and use it again the next time. It's easy to extract the soap from the paper cups, and they're cheap and nice and round.

So here's an updated base recipe. Go forth and wash!