We love using our homemade soap and recently made enough to last us a couple of years. We made one batch using used cooking oil and animal fat we had stored in the freezer. The other batch is made from coconut and olive oils. I took pictures of the batch made from used cooking oil and animal fat. (See instructions at end of article)
I am including the recipe we use for the coconut/olive oil soap which is excellent as a bath soap and makes a lot of lather. There are many good recipes on the internet and in soap-making books.
We buy commercially-made lye which makes it easier to determine the formula to use. However, lye can also be made from wood ashes if commercial lye is unavailable. The varying strength of homemade lye will lead to unpredictable results. That is one reason homemade lye soap has a reputation for being harsh.
Tools and supplies
- Stick Blender (Less than $20 at Walmart.)
- Molds for the soap. They need to be made of silicon (or other heat tolerant material) if you’re going to oven cure the soap. Glass will work but it’s very hard to get the soap out. Silicon loaf pans work best.
- Measuring scale accurate to at least 1 gram. Some recipes are given in ounces but it’s easier to work with grams than hundredths of an ounce. (1 gram = 0.035 oz)
- Thermometer : glass or infra-red.
- Goggles for eye protection, Rubber gloves (optional)
- A bottle of vinegar, and a wash cloth wetted with vinegar. Lye causes chemical burns to skin, counter tops, and flooring–vinegar will neutralize it. If you start to feel a burning sensation on your skin, wipe it with the vinegar-cloth.
- Newspaper to cover counters and floor
- Parchment paper cut so it will contact the soap in the molds.
- Sheet pan covered with foil or parchment paper. (To hold soap while curing.)
- Rubber spatula
- A container to make the soap in. It can’t be made of aluminum–the lye will react with it. Plastic is ok as long as it can handle temperatures of about 150°. Stainless steel works. A tall container is better than a squat one to avoid splashes from the stick blender. The container should be approximately twice as large as the batch you’re making–again to minimize splashing outside the container.
- Use a recipe or a Lye Calculator
- Lye—Make sure the container says “Pure Lye” and/or 100% Sodium Hydroxide.
- Preservatives–if used. Food grade BHT and Food Grade Sodium Citrate. Amazon or some health food stores.
- Scents–if used. (Best bought from stores or web sites that specialize in soap making –some such as clove oil, can cause the soap to solidify too quickly. Soap making specialists will warn you of the problematic ones.)
- Cover your work area with newspapers and arrange all your equipment.
- Weigh a 50/50 mixture of water and ice cubes per your recipe in a heat proof container. The container needs to be at least twice as big as the amount of water to contain splattering and have room for the lye.
- Water: __________ grams
- Note total weight of container and liquid. (So you can double-check the amount of lye added.)
- Goggles! Weigh the Lye per your recipe into a non-plastic container. (The Lye crystals will stick to plastic)
- Lye: __________ grams
- Put the heat proof container with ice water on the scale and zero it.
- Goggles! Very slowly add the Lye while constantly stirring. It will get cloudy and very hot, melting the ice cubes. Stir until the solution is clear again and there are no undissolved crystals.
- Let cool to about 110-120 degrees.
- Check the weight–you may need to add a little more lye if any stuck to its container.
- Rinse and soak any lye containers, spoons, etc.
- Check the work space for any errant lye crystals.
- Weigh your oil into a non-aluminum container at least twice as large as the amount of oil plus the lye solution.
- Heat or let cool until it’s between 110-120 degrees. If your lye water or the oil is outside this range, the soap will gel too slowly or too quickly.
- Oil 1 kind: ________ ___________ grams
- Oil 2 kind: ________ ___________ grams
- Oil 3 kind: ________ ___________ grams
- Add preservatives to the oil (probably not necessary if you’re using fresh oil and won’t be storing the soap for a long time.)
- 1 part per thousand of food grade BHT
- .001 X total weight of oil, lye, and water: _______ grams
- 1 part per thousand of food grade Sodium Citrate
- .001 X total weight of oil, lye, and water: _______ grams
- Preheat your oven to 175°–as low as 150° is better if your oven goes that low.
- Oven curing is optional–it speeds up the curing process. If you’re making fancy soaps, slower curing at 70°-80° for several days may give you better looking soap–although it may not be useable for a month or two.
- Cheap plastic soap molds may melt or distort with oven curing. Silicone molds are the best.
- Goggles! Slowly pour the lye solution into the oil, while stirring with the hand blender powered off. Stir for a minute or two until the oil becomes cloudy, then power on the hand blender.
- Fill the now empty lye solution container with water to soak.
- MAKE SURE THE BLADE IS ON THE BOTTOM AT ALL TIMES.
- You don’t want Lye flying through the air
- You don’t want air in your soap. (Unless you’re trying to make a soap that floats.)
- Mix, alternating manual stirring and power stirring every 30 seconds or so. You don’t want to burn out the tiny motor. When the mixture takes the appeareance of a thin custard, power off your blender and check for trace. “Trace” means the soap is thick enough that drippings from the turned-off blender make a semi-permanent trace across the surface.
- Getting to trace can take a few minutes or over half an hour. It partly depends on the starting temperature of your oil and lye. Colder = slower, warmer = faster. It also depends on the types of oils you used.
- Add any essential oils, and quickly stir a little more to get everything mixed up together. Some essential oils will accelerate hardening.
- Quickly pour the mixture into your molds and cover with parchment paper in contact with the soap.
- Place the molds in the preheated 150-175¡ oven. (Optional)
- After one hour, turn the oven off and leave the soap inside to slowly cool for at least 12 hours. Don’t peek, poke, jiggle or otherwise fiddle with the soap. Just walk away and leave it alone.
- Wrap soap molds in old towels or rugs, etc. to retain heat. Place in a warm room temperature spot for 24 hours or so.
- Clean up your work area!
- Rinse all containers with plenty of water to neutralize any lye or partially cured soap.
- Wipe down the stick blender and it’s cord with the vinegar-wetted cloth.
- Carefully fold up the newspapers.
- Wipe down the backsplash and anything else where lye or soap may have splashed using the vinegar soaked cloth.
- After 12 hours or so in the oven or 24 hours or so at warm room temperature, extract the soap from the molds and if necessary, cut into bars.
- At this point, the soap is about the consistency of modeling clay and is easily cut with a knife. Any scraps can be pressed into a ball. (If you wait longer than a day, the soap starts to harden and becomes harder to cut.)
Test for Safety
- The chemical reaction is mostly complete and the soap should be safe to use if your recipe was accurate and followed.
- Wet the inside of your wrist and rub a little soap on it. If it starts to itch or burn, your batch has too much lye in it. Quickly rinse it off. Let the soap cure for a month or two and try again. If it still irritates your skin, don’t use it!
- If and when the soap doesn’t irritate your skin, try the taste test. Touch the tip of your wet tongue to the soap.
- If it stings, rinse your mouth with water and let the soap cure for a month or two and taste again.
- If it doesn’t sting, lick the soap. If it’s tasteless or tastes like mild soap–great! If it looks or tastes oily, you didn’t use enough lye–let it cure for a month or two. Oily soap is safe to use. A little extra oil makes a moisturizing soap. A lot of extra oil makes an ineffective soap.
- Allow the soap to dry and harden to your desired consistency. Anywhere from a few weeks to a few months or longer
Bath Soap Recipe
- 1000 grams of Olive Oil (cheap works, extra virgin gives the soap a green color)
- 500 grams of Coconut Oil (the cheap 76° Lou-Ann brand from Walmart)
- 216 grams of Lye
- 376 grams of Water
- Gets to trace within a few minutes.
- Water is the only ingredient you can vary from your recipe or Lye-Calculator. A low-water bar will initially be harder than a high-water bar. A low-water soap traces faster and is more resistant to separation than a high-water soap–especially one with olive oil. Low-water soaps start out harder than high-water soaps, but they eventually (weeks or months) reach the same hardness.
- For this recipe: 216g of water would be very low, 324 med, 429 med-high, 600 high, and 864 very high.
- This recipe fills two silicon loaf molds 2.5″ x 7.9″ x 3.4″ and should be made in a tall mixing container that’s 1 gallon or larger.
The fat we recently used for soap was made from bacon fat, used cooking oil, and trimmings from pork and beef that we accumulated in the freezer.
- We rendered trimmings on sheet pans in the oven.
- Wash the fats and used oils.
- Melt fats and oils in an equal amount of water. Keep the temperature below 150° so the water isn’t close to it’s boiling point.
- Blend together and then let separate (several hours)
- Pour off the fats and oils from the water and crumbs
- Repeat these steps–mixing with water and allowing to separate until the fat & oil is clean and loses any odor such as bacon or chicken wings.
- Filter the cleaned fat & oil through a coffee filter or fine cloth.
- Replace the coffee filter as it becomes clogged.
- Slowly heat the fat & oil to evaporate any remaining water–stirring occasionally. Watch the temperature–by the time the fat & oil gets much above 212 degrees, (250 at the most), that’s good enough.
Warning: This needs slow heating or any significant water on the bottom of the pan can explode through the fat & oil causing burns or a fire.
- Allow the fat & oil to cool and use in the recipe.