Scary Old Soap Recipes (Halloween for a soap maker)

 The idea for a post on scary old soap recipes was inspired by a recipe my grandpa found for me several months ago. It really made me curious about other bizarre soap recipes from the past that I could analyze. 

Before we dive into these recipes, I want to make it very clear that you SHOULD NOT make them! I think that will become pretty clear as we go along, but I wanted to add this disclaimer from the start. 

Recipe #1: Laundry Soap?

My grandpa photo-copied this recipe for me from an old family cookbook. Let's talk about why this recipe is so scary: 


The first thing that obviously stands out is the ammonia and gasoline! Hot oil and lye require safety precautions on their own. Adding ammonia and gasoline to that combination would require A LOT of skill and safety. This recipe was probably made outside in a vat, and not in the house because the fumes from this mix would be terrible! 

The other issue with this recipe is the generalized measurements. Modern soap makers measure ingredients in ounces and grams in order to prevent making a lye-heavy (caustic) soap. Too much lye, and you have a soap that can burn your skin. 

So why use the gasoline and ammonia?

Long ago, both of these ingredients were actually a very practical addition to the recipe. Ammonia helped to make the soap more soluble in water, and after saponification, the smell wouldn't linger in the soap. It was also really effective at removing oil and grease from really dirty clothes and hands.  Gasoline wouldn't have saponified in the soap like the ammonia, but it was also an effective ingredient for cutting grease. Maybe in a future blog post I'll also go into the purposes behind using borax, and rain water instead of well water. The chemistry of soap making is so fascinating!! Let me know if this is something you'd be interested in reading! 


Despite the shock factor this recipe creates today, it was genuinely a practical, and effective cleaner for a farmer's wife in the decades and centuries past. She would have used what was available to her, and the engineering of this soap for optimum cleaning properties is impressive. However, there are so many safety risks in the process of even making this soap that it's just not worth it to me. There are MUCH safer soap recipes to be made that are also effective cleansers. 

Recipe #2: Medieval Soap 

A year ago, I stumbled across a collection of soap recipes from the Middle Ages through the Renaissance compiled by Susan Verberg. I've been obsessed with these recipes, and wanted the perfect time to debut this research. 

The following recipe is one of the more specific recipes in this collection. Let's break this one down!

The first thing to note is the word "capitellum." This referred to a highly concentrated lye solution made by filtering water through wood ash. At the time, lye was something that the common person had to make at home. There were different tests one could perform to determine the strength of the lye solution, but none that were as accurate as what our tools and measurements can do today. Just like the previous recipe, we are working with fairly vague measurements that won't allow us to know exactly how caustic our soap is.

But wait! You can taste it! That's what makes this recipe particularly scary. Not sure how concentrated your lye solution is? Taste it. The best capitellum will be "strong" on the tongue. (yeah, because it's an extremely caustic solution). The recipe also seems to imply that the soap maker is tasting the soap along the way too, and once it's less strong, then the oils/grease and capitellum have made a nice soap. This is my interpretation of the recipe. Let me know if you think the instructions are explaining this differently! 


This "taste-test" would have been helpful in the medieval era for helping a soap maker know the strength of their lye solution, and allow them to adjust the recipe to create a nice bar of soap. However, this is NOT a safe method. I will not be encouraging any taste testing during the soap making process. 

Bonus Recipes: Some dubious medical advice and remedies

Regular bathing was not a common practice in the 15th and 16th centuries. People kept their bodies clean by regularly changing their undergarments, and scrubbing themselves with linen cloths. I highly recommend Ruth Goodman's book "How to be a Tudor" to learn more about life and hygiene during this era.

However, soap was important for laundry and medicine. Used both internally and externally, soap is found in many recipes from apothecaries of old. Below I've included a few of my favorites from Susan Verberg's compilation: 

External medicine: 

 Internal medicine:


My transcription: "Take white Spanish soap and a little stale ale in a cup and rub the soap against the cup's bottom until that the ale be white, and then shave in a half penny weight of ivory and let the sick drink it at morn and even till he (be healed?) it hath be often proved and found true." (Morphewe refers to sores and possibly also leprosy)

Final Takeaways: 

Though I certainly can't recommend any of the above recipes, I really enjoyed learning more about the history of soap making and the purpose behind some of the ingredients and methods.

If you're interested in reading the soap compendium for yourself, here is the link for the free download:

 And here's a link to Ruth Goodman's book:

Until next time!


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