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How to make Zero Waste homemade soap!

How to turn any old oil into zero waste homemade soap. DIY soap making at its best!

You saw it first on farmstand culture. Find out: what is zero waste homemade soap, when and how to make it yourself. And, if you’re more into learning and watching rather than DIYing, read on for my personal experience with zero-waste soap making. I hope it inspires other positive, natural-lifestyle changes in your every day life.

It all started about a decade ago, before my sister and I had children. We loved the handmade soaps at Sunflower Farm Shop in Orange, Connecticut, and felt inspired to try making our own soap from scratch.

We spent about $100 on materials and equipment to get us started and spent an evening chatting, measuring and mixing up two batches of pure, chemical-free soap. You would never know it was only our first try. Those soaps came out great. My friends and colleagues asked me to make more…for years, but with kids and work and house and school and and and…it was nearly ten years before I made my next batch of handcrafted soap.

Find out how I use any old oils laying around the house to make zero waste homemade soap. DIY soap at its best!

Inspiration hit

Several months ago I looked in the cabinet and noticed a massive vat of expired organic coconut oil. Do you know how expensive those are?

We buy most of our pantry goods at an American wholesale club. Picture a legitimate warehouse, open to the public, with shelves stacked to the ceiling full of giant versions of everyday items.

Laundry detergent the size of a backpack. Whole fillets of king salmon that fill a tray so big, it is hard to carry. The coconut oil they sell is huge, approximately the size of eight normal jars of coconut oil. And, we only used half of our expired coconut oil. Ugh.

I felt annoyed and upset that we wasted the equivalent of a year’s worth of coconut oil. Clearly, we went through a coconut oil phase that faded before the supply ran out. But, when I opened it, the oil smelled fine. I was not about to throw it away. First, I made a coconut-coffee sugar scrub with some of it. A few days later, true inspiration hit…

Zero-waste soap

Back when my sister and I experimented with hand-crafted soap, we created our own recipes using online calculators. With these free calculators, you simply type in different quantities of whatever oils you have, and it tells you exactly how much lye and water you need to make your soap. 

Lye is dangerous but necessary to saponify (i.e. turn fats and oils into soap). Pretty much any natural fat will saponfiy if mixed with liquefied lye. Brilliant!

No need to waste that old coconut oil. It smelled fine and rather than eat it, I can turn it into soap! So I did. Here’s what happened…

My experiment

First, I ordered lye on Amazon. Be careful. Lye is dangerous and scary. It causes permanent burns to bare skin. Kids should never, ever be around lye. Grown-ups are barely trust-worthy around lye.

Then, I awoke our soap-making pots, measuring cups, and thermometers from their decade-long slumber. If you want to make soap, dedicate the materials to soap-making just in case there’s somehow some leftover lye or soap in them. Put labels on your soap-only cups, bowls and spoons. 

Almost there. I had gloves, but still needed a kitchen scale to weigh everything. At the end of the post, I’ll give you all the links to the key materials you need to make zero-waste soap yourself.

Creating zero waste soap recipes

I worked up a recipe for a simple coconut oil and olive oil soap, but since I found a small bottle of really old sweet almond oil, I threw that in, too. It passed my sniff test. If you find random old oils around the house, just measure how much you have and add it to your online soap calculator. Easy. 

Go through your cabinets and pantry and see if you have some old oils hanging around. Then, weigh them on your kitchen scale and enter the amounts you have into an online calculator. Sometimes, soap-makers call them either lye calculators or soap calculators. Same thing.

Here’s a good soap calculator: SoapCalc and here is a round-up post from The Spruce Crafts that mentions five others. Don’t be intimidated. The calculators look complicated at first, but once you start using them, it gets easier. If you really just want a very simple lye calculator for soapmaking, this one by TheSage is easy to use. 

Soap-making process and tips

Here is a recipe and video for cold process soap from Becky’s Homestead that inspired me to add olive oil to my zero waste coconut soap. You don’t have to add other oils. But, I like a softer bar of soap, and as she mentions in the video, coconut oil makes harder bars.

Cold process soap is made without heating the oil and lye mixture over a stove or in a crock pot; that would be hot process soap. As a beginner, I started with cold process soap-making, but it takes longer to cure (i.e. you have to wait a month before you can use your soap). 

Instead of rosemary oil, I used a half ounce of ginger essential oil in my zero waste soap for fragrance (because that’s what I had), and I didn’t add any color. 

Instead of using a mask and fan like Becky, I mixed my lye into the water outside and let it cool outside. I never open lye in the house. It’s personal preference. And, as the lye water cooled, I hid it outside away from kids and animals. 

If this is your first time bringing soap to “trace”, watch a few videos to get a better feel for the pudding-like consistency you need before you can pour your soap into the molds. 

You don’t need a fancy mold. You can use any old plastic container or even an old shoe box. TIP: line the mold with strips of parchment paper before you pour in the soap. Parchment strips make it easier to remove the soap the next day to cut it into bars. 

How to make zero waste homemade soap. DIY soap recipe

My mistake

After my soap hardened, I noticed that the outside dried lighter with some soda ash, and the middle dried darker. It doesn’t really matter. The soap works beautifully. Actually, it’s amazing how simple this soap recipe is, given how well it suds and cleans. However, my soap probably wouldn’t sell well at a farm stand. It’s not perfect. But, I think I understand my mistake.

I blended the lye mixture and oils when they cooled to 100 degrees Fahrenheit. But, it was cold that day. And, I mixed the lye outdoors and left it in the freezing cold. I think it would be better to blend my ingredients at a slightly higher temperature, maybe 110 to 120 degrees. 

Zero waste soap-making materials

You probably already own a mixing spoon, cups and bowls. Here’s a list of the less common materials you need to make your own zero waste soap at home.

Kitchen scale
Thermometer (You need one. I use two.)
Immersion blender (Don’t use this for food if you use it to blend lye into soap.)
Long rubber gloves
Protective eyeglasses

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Leave us a comment and let us know if you made some soap. What was your experience like?

Do you have old oils laying around the house that would make great zero waste soap? I will be asking my friends and family to bring me theirs!

6 thoughts on “How to make Zero Waste homemade soap!

  1. This reminds me. My grandmother used to make soap but I never paid any attention to how she made it. I just took it for granted.

    1. That is so cool. All you really need is a source of fat – animal or plant – water and lye.

  2. […] are some tips on how to use almost any oil laying around your house to make soap. You really just need a basic […]

  3. […] are some tips on how to use almost any oil laying around your house to make soap. You really just need a basic […]

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