Making Shaving Soap

[Raissermesser]

File this under "Like I Need Another Obsession."

The recent talk on soap making had me looking into it to the point of reading public domain books on soap making. These were geared toward commercial and not amateur or small level batches. There's been a century on average of technological advances, though the basic chemistry is likely the same. But I still have questions. Lots and lots of questions.

For instance, hot process vs cold process. Hot process speeds saponification allowing for curing time measured in weeks vs months, and in some soaps the separation of glycerin from the batch and things like whipping to include air. But pouring can be lumpy and heat and constant attention is involved. At least, it would be on my fish cooker. I don't think my wife would want me to appropriate the crock pot. Cold process uses the heat of the reaction of the caustic with the water and fats to help drive saponification. No extra heat, besides melting the fats and oils together, is needed, and it pours smoother. But because there's no extra heat, curing can take months for the caustic to completely react with the fats and oils.

Since according to one source, the addition of "potash lye" prevents the separation of glycerine, does this mean there's no benefit, other than curing speed, of hot process over cold for shaving soaps? Looking at the nice, plastic, container than seems to have doubled as a mold for Van Der Hagan, does this mean cold process is used in industry?

One weird question: Since one type of soap can be used for a number of fragrances, is it possible to produce a large batch of soap, then, after it cures, mill it down and rebatch to add essential oils and other niceties?

 

[JBLA]

Here's a few answers:

Properly done, hot process soap does not need to be cured. That's the whole point of the hot process, in that the added heat speeds the reaction so that by the time the soap is cooked, it is safe and ready to use. (Once it's cooled down, obviously, do not apply soap lava to your face.)

Cold process soap takes some time to cure, but this tends to be days or possibly weeks. Some companies (MDC I believe, among others) let their soaps cure for months, because it allows more moisture to evaporate and makes for a harder bar.

The purpose of Potash Lye (aka Potassium Hydroxide aka KOH) is to turn the base oils into soap. Without lye, there is no soap. (Some soapmakers use Sodium Hydroxide (NaOH) to make a harder bar. You'll have to experiment to see which works better for you. (I've found potassium hydroxide makes for a slicker lather. YMMV.)

The benefit of hot process over cold process for shaving soaps is that it makes the process faster and easier. Shaving soap typically contains a large amount of stearic acid, which tends to "seize" almost immediately when the lye water mixture is added, making it very hard to properly mix in the absence of a heat source. (You are correct though, that for making bath soap, the cold process method using other oils does tend to pour more smoothly and allow for detailed moldings.)

Industrial makers of soap typically use industrial cooking/soapmaking processes for making shaving soap, that are beyond the basic hot process / cold process methods, but the traditional cold process would be much too inefficient for industrial production.

You can certainly make a large batch of plain soap and then mill it and rebatch it to add essential oils and other goodies.

Good luck with your soapmaking!

 

[eyebright]

To answer the last question first, yes, you can add fragrance to an unscented soap base, by cutting/shredding/melting the soap and rebatching it with the fragrance (not to be confused with milling, which is a process requiring commercial machinery and specific types of soap).

 

[Raissermesser]

Industrial makers of soap typically use industrial cooking/soapmaking processes for making shaving soap, that are beyond the basic hot process / cold process methods, but the traditional cold process would be much too inefficient for industrial production.

Thanks. Even with hot process, I'd let my hypothetical first batch set because, well, it would be my first batch. I've been toying with ideas of constructing a double-boiler for the fish cooker, looking at iron, though I'm dubious of rigging a cast iron double boiler because cast iron is brittle, and the pots are apt to have some age on them.

I didn't ask what is potentially the most important question. I was looking through some old soap fragrance recipes, and noted Oil of Bitter Almond as an ingredient. But . . . well, Bitter Almond is toxic.

The reason this fragrance-free guy is looking at essential oils is part of my notion is to try to recreate 19th Century style shaving soaps. It'll probably go much of nowhere, due to the cooker - I'd really like to do this outside - but it's fun learning about it.

 

[kingfisher]

You should be able to find a cheap, used crockpot at a garage sale or on craigslist or something for about 10 bucks. No need to appropriate your wife's crockpot.

 

[Fordfather]

You should be able to find a cheap, used crockpot at a garage sale or on craigslist or something for about 10 bucks. No need to appropriate your wife's crockpot.

+1. Thrift stores are a great place to look, also!