How to Make Laundry Soap at Home

Homemade Laundry Soap is Easy and Cost-Effective to Make Yourself


Not long after I learned how to make homemade soap, I tweaked the recipe and learned how to make laundry soap. Those other “homemade laundry soap” recipes had flaws.

Homesteading mommy blogs claimed I could make my own laundry soap by grating a commercial bar that had an age-old recipe. Mix two parts borax, two parts washing soda, and one part grated soap. But that isn’t homemade as much as it’s home-mixed.

Why Use Homemade Laundry Soap?

Compared to boxes of powdered commercial detergent, homemade soap has advantages. “Detergent,” which is made with chemicals and has powerful surfactants, may have ingredients such as fragrance or color-brighteners which irritate skin or respiratory airways. It also may contain montmorillonite clay as a filler, an ingredient which can clog septic systems.

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The commercial laundry detergent industry may be another reason to switch. Have you noticed how so many companies now offer “concentrated” liquid detergents, so you use less? Basically, there is less water in each ounce. But, though you use less detergent, the bottle is more expensive and the price per amount of actual cleanser isn’t much different.

And look at that cap or scoop. Is it huge, while the line designating the maximum soap needed is halfway down? You’re not being scammed here because it’s up to you to look at your scoop and realize you’re adding twice as much detergent if you fill it all the way up. But how many people only fill to the line? Companies know people will fill the scoop and use more, necessitating another trip to the store.


And What About That Laundry Bar?

The biggest reason I researched how to make laundry soap wasn’t because that soap bar was bad. Other than containing a few ingredients I don’t need, such as titanium dioxide and a fragrance that doesn’t scent the laundry anyway, the product is good. But it’s not truly homemade.

I want homemade laundry soap, as “homemade” as possible, with complete control over my ingredients. I don’t want to search through stores, realize my town doesn’t carry that bar, and then have to search online before I can start. Perhaps I need a vegan product, not one containing “sodium tallowate,” the saponified product of lard or beef fat. Perhaps I need it to be kosher and don’t know if that “tallow” is from pigs. I have many reasons.

Why Can’t I Grate Down my Own Homemade Soap Recipe?

Beginning soapmakers learn how to make shea butter soap, a luxurious and skin-softening recipe, but make cosmetic mistakes resulting in ugly soap. So they grate it down for laundry. The first two loads come out fine then they realize their clothes feel tacky and have little oil spots. This is because the superfat level in shea butter soap, which gives those skin-softening properties and protects against a lye-heavy recipe, adds unnecessary oil to laundry. That oil has to go somewhere: either through the drainpipe or onto clothes. The same problem exists with goat milk soap recipes. It’s that superfat percentage, which makes a good body bar, that causes issues with laundry.

The solution is to use 100 percent coconut oil, which is so cleansing that soapmakers are warned to avoid surpassing 20 percent in a bath bar because it can dry skin. That cleansing factor lifts oils and odors from clothing, washing them away. And gets rid of that superfat.

Wait…superfatting avoids lye-heavy soap!

Yes, I know. Laundry detergents are already alkaline, as is that washing soda you’re going to add later in the recipe. Alkalinity counteracts the acidity of oil and bacterial byproducts. It’s good. Just don’t eat it or use it in the shower.

Follow the instructions regarding how to make coconut oil soap. With a lye calculator, reduce superfat to zero. And, since it doesn’t have to be pretty, hot process it in a slow cooker.


How to Make Laundry Soap, Crockpot Style

Hot processing soap reduces cure time. Soap is ready within a day or two. But the finished product can be chunky and doesn’t allow the beautiful swirls attained with cold process. That won’t matter with laundry soap.

Prepare your recipe. Check it with a lye calculator. Now check it again. Get a slow cooker, your lye and distilled water, coconut oil, a digital scale, immersion blender, and protective gear. Don’t add color because you don’t want it to come out on your clothing. A fragrance is optional, it won’t scent the finished laundry anyway.

In a slow cooker that will never again be used for food, melt solid coconut oil on low. When it’s almost liquid, measure water then add the lye. Stir until the lye dissolves. Carefully pour the lye water into the slow cooker, avoiding splashes. Use an immersion blender to stir until the soap reaches trace, the point where it thickens to look like vanilla pudding. This doesn’t take long at all with 100 percent coconut oil soap. Now place the lid on the slow cooker and let it cook, still on low. The soap will harden then start to bubble around the edges. When the bubbles fold inward like a reverse volcano made of petroleum jelly, stir then pour into a prepared mold.

Let the soap cool, but unmold and cut into individual bars while it’s still slightly warm or it may be too hard. Bar shape doesn’t matter; cutting is just so you’re not grating a huge loaf of soap.

After soap cures a couple days, “zap” test to be sure it’s not still lye-heavy. This involves touching your tongue to the soap. If you feel a zap, let it sit another day or so. If it tastes like soap, grate enough to pulse in a food processor. Measure one part ground soap, two parts washing soda and two parts borax (both available in the laundry department of most department stores) and pulse again, until well mixed.

Store in an airtight container, as this soap hardens if moisture gets in. If it does harden, simply loosen with a spoon or grind again in a food processor.

Use one to three tablespoons soap for each load of laundry.

Special Considerations when Using Homemade Soap for Laundry

Chemical detergents have one big advantage: they rinse clean, with very little effort. True soap can leave a residue. Reducing the superfat does reduce soap scum left behind, and a zero percent superfat coconut oil recipe has remarkably little to leave.

When choosing true soap over detergent, that residue can be a huge factor, especially in high-efficiency washing machines. Gunking up machines or septic systems may sway your decision to otherwise go all-natural.

Homemade laundry products are generally considered safer for septic systems than powdered detergents because they do not contain clay or other fillers. Avoid antibacterial additives, which can disrupt the bacterial process that breaks down waste within the tank. Many homeowners with septic systems run wash water directly into the tank, versus in the drain field, so the soap doesn’t clog pores in the field. To avoid washing too much soap into a septic system, scrape soapmaking residue into the trash before washing pans.

Avoid soap recipes that have pieces of anything, such as oatmeal or pumice, as they can get caught on any residue already on filters. Once in a while, clean your washer and drains by running a cycle without laundry but with a cup of distilled vinegar in the drum.

Now that you know how to make laundry soap at home, will you be giving it a try?

  • What a great article! I’m also a soapmaker. I just want to clarify this statement that I took wrong and could see how other readers might too:
    “melt solid coconut oil on low. When it’s almost liquid, measure water then add the lye. Stir until the lye dissolves. ”
    Make sure that you add the lye and water in a separate container until the lye is dissolved. Do not add undissolved lye and then water into the coconut oil. 🙂
    Great recipe and article! I make my laundry bars from 100% lard cold process but coconut oil is a good alternative for vegan option!

  • Thanks so much for this timely article. Just this morning I was trying to figure out what to do with about 2 lb of soap bars from my first soap-making experience 5 years ago. It seized before molding, so it is ugly; and it has lost all of its scent. Grating and using for laundry soap seemed reasonable…until I read your article. Now I know what NOT to do with this soap. I’m still not sure what I SHOULD do with it.


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