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Guest Post! Make Your Own Soap

I’m part of a like-minded Facebook group of zero-wasters in NH and recently saw a post where Amy Lamb generously offered to give away some of her homemade soap. Of course, I jumped at the chance to learn more and asked Amy to share her recipe with us on GreenLifeNH. Amy graciously accepted and wrote this thorough and interesting post for us. I think this project would be fun to do on your own or with older kids. Thanks, Amy! I’m excited to try it! – Rachel

Hi All! Amy here, member of the Zero Waste NH facebook group, avid DIYer, and guest blogger today on GreenLifeNH! I have been making my own soap on and off for several years now, and I must say that every time I dust off the supplies and make a batch from start to finish, I remember how easy and inexpensive it is. I wonder why I don’t do it more often.

Like many hobbies, the biggest investment is the supplies; to make your own soap, you will want to have a set of designated tools that you use for soap-making and soap-making only. One of the ingredients in soap-making is lye, which is very caustic and can damage materials and utensils over time, and is also something you don’t want to consume! But, don’t worry! Once the chemical reaction of saponification, or creating soap, is complete, no lye remains. It is just better to take precautions and be safe when working with and handling lye.

The supplies that you will need for this recipe are:

  1. Old crockpot (or extra ceramic liner) that is no longer used for food

  2. Tempered glass measuring container such as an old coffee pot, Pyrex measuring cup, or Mason jar (I have only used the coffee pot method, but any glass that is tempered to handle hot liquids should work.)

  3. Wooden spoon (must be a non-reactive material; avoid metal)

  4. Kitchen scale (this doesn’t have to be designated for soap-making only)

  5. Immersion blender

  6. Thermometer

  7. Gloves, mask, and goggles

  8. Soap mold (This is the fun part! Raid your recycling bin for OJ or milk cartons, boxes, cardboard tubes, and plastic containers. If the material is not waxed/shiny, you will want to line with parchment paper. You can also use a loaf pan or proper soap mold.)

Once you have your soapmaking kit, you’re ready to get started! Creating soap requires three key ingredients:

  1. Oils and/or fats

  2. Lye (or more scientifically, sodium hydroxide)

  3. Water

Lye is first combined with the water, which makes it dissolve and also gives off heat. Then, the fats/oils are melted. Once the ingredients are about the same temperature, the lye-water solution is added to the fats/oils. A chemical reaction occurs, which is sped-up by an immersion blender, and the mixture starts to get a puddling-like consistency, called “trace”. In “hot process” soap recipes, the mixture is cooked in a crock pot to further speed-up the chemical reaction, and the resulting soap does not need to sit before using. With “cold-process” recipes, the resulting soap has to cure so that the chemical reaction completes, which can take several weeks. I like hot process soap because it is ready to use almost immediately.

The recipe I am sharing today is for a utilitarian soap: it’s great for washing dishes and creating your own powdered or liquid laundry soap (recipe at the end!). It’s not recommended as a body soap, since it is only “superfatted” to 1%. That means that the recipe has very little excess fat, which is what gives soap its skin conditioning properties. Instead, most of the fat reacts with lye during saponification, making this a great cleaning bar. That said, it is the only bar next to my kitchen sink and I have used it to wash hands with no adverse effects. I also like that this recipe uses what is often thought of as a waste product – lard (pork fat) – which can be obtained from local farmers.


2 lb lard

4.4 oz lye

10 oz distilled water

***Note: You can also use tallow, lard, or a solid vegetable oil, but you MUST run the recipe through a lye calculator since different fats require different amounts of lye and oil.

Steps: (For more detail, see this recipe!)

  1. Measure ingredients using kitchen scale, each in separate containers. (Lye is best measured in an item rescued from the recycling bin, or a paper cup.) Important: measure as exactly as you can. Err on the side of less lye rather than more.

  2. Add the water to the tempered glass container. Using goggles, gloves, and eye protection, carefully sprinkle in the lye, and stir with the wooden spoon until dissolved (DO NOT add water to lye, ALWAYS add lye to water, or else there may be a strong reaction!). Allow to cool so that mixture is warm but not hot.

  3. Add fat to crock pot and allow to melt over low heat.

  4. Add cooled lye solution to melted fat, and stir to combine.

  5. Use the immersion blender to thoroughly mix fat and lye solution for 3-5 minutes until mixture begins to thicken, or “trace”.

  6. Cover crock pot and allow mixture to “cook” for one hour. You can stir occasionally to make sure that mixture cooks evenly. When done, mixture should look like the image below, a bit chunky and soap-like. It’s a bit odd, but you can test for doneness by touching a tiny bit of the mixture to your tongue; if you feel a slight “zap” sensation, soap needs to continue cooking. If you just taste soap, then it’s done! Spit profusely.

  7. Prepare your molds (line with parchment paper if using). Spoon soap into molds and smooth over top. Work quickly because soap begins setting as it cools.

  8. Allow to sit for 24 hours, then slice into bars.

  9. You can use immediately, and/or store remaining bars in a cool, dry place and spaced well to allow for good air flow. Use for doing dishes or you make your own laundry soap – recipe below. Enjoy!

DIY laundry soap powder:

Grate soap using a microplane zester (works best and easiest to clean). Mix equal parts grated soap with Super Washing Soda. Add essential oils to your taste – I like lavender especially.

(As always when working with chemicals and hot water, please do so cautiously and at your own risk. Thank you!)

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