I made a mistake in my soapmaking this past Saturday that I’m really looking forward to seeing how it turns out.
Let me provide a bit of background. When I’m setting out to make several batches of SunSoap, I do a fair bit of prep work. I mix up a giant vat of the relevant oils and heat them together, and measure out lye in the appropriate quantities to make the assorted batch sizes to fit my various molds. Then for each individual batch I weigh out the right amount of the mixed oils, add the relevant lye allotment, and color/fragrance as desired.
Well, on Saturday I got a bit too caught up in what I was doing and measured out too much oil for one batch – basically, I measured out enough oil for a five-pound batch despite using a four-pound mold. This wouldn’t have been a significant error if I’d also grabbed a five-pound allotment of lye; I’d’ve had too much soap for the mold, but I could have put the extra somewhere else. But no; I used the four-pound allotment of lye, and didn’t realize the mistake until the soap was colored, fragranced, and poured into the mold. Which means this batch of soap is now about 30% superfatted instead of the desired 3% or so.
What is superfatting? It’s a technique used by many artisan soapmakers to provide an extra moisturizing bar of soap by including some excess in the oil phase which will remain unreacted with the lye and remain in the finished soap. Often, carefully-selected oils are added very late in the soapmaking process in an attempt to make these oils more likely to be among those unreacted with the lye and present a particular profile in the moisturizing aspect. I’m not 100% convinced that doing this actually does have any significant effect on which oils remain behind in the finished soap, but this doesn’t stop me from adding the avocado oil late in my soaping process. After all, it can’t hurt, right?
The technique of superfatting very likely arose not primarily as a means of making soap more moisturizing per se, and more as a way of allowing for inaccuracies of early soapmaking methods and ensuring that no lye remained unreacted in the finished soap. Without accurate scales – or, even earlier in soapmaking history, without lye of known strength – it was difficult to know one had added the correct amount of lye, and if it is virtually certain there will be unreacted ingredients in the finished product, it’s better and safer that they be oil rather than lye. Hence, superfatting. This is rarely a problem with modern methodology, but sufficient other benefits are forthcoming that a modest percentage of superfatting is almost universally used.
It’s not a technique without shortcomings, however. Highly superfatted soap doesn’t lather as well. Also, if too much excess oil is used, it can create large enough deposits in the soap that it can oxidize and create what is known in the trade as the Dreaded Orange Spots. This is not the necessarily kiss of death for soap, but it is rather unsightly, and in extreme cases the afflicted soap can actually go rancid. Yuck! So I try to keep my superfatting percentages below 5%, as a compromise between moisturizing and lather, and to stay well below the DOS threshold.
So what does this mean for my accidental 30% superfatted soap? Well, obviously it won’t be leaving my hands; if ever a soap were likely to go off in interesting ways, this would be it, and I don’t want that to happen out in the wild. But I’m fascinated to watch how it behaves, once it cures a bit. Will it be too soft to hold a bar shape? Will it lather at all, or just sort of sit there greasily? Will it develop Dreaded Orange Spots within the month? I have no idea! But despite dumping the batch out of the mold and replacing it there with a properly-made batch, I kept this around in a plastic box to let it progress as it will. For Science!, don’tyaknow. If I learn anything remotely interesting, I’ll let you know.