Answering Your Questions: The Chemistry of Big Batch Powdered Laundry Soap


One of the most popular recipes I’ve written about here at The Make Your Own Zone continues to be the Big Batch Powdered Laundry Soap recipe.  In a nutshell, this recipes mixes together one complete box of washing soda, one complete box of borax, and a grated bar of Fels Naptha laundry soap.  You use two tablespoons of this powdered mix for a load of laundry.

homemade powdered laundry soap

I recently received some questions about this mixture from Valerie who left the following comment:

“I made this recipe using 3 bars of Ivory soap. I had someone comment that this will not work because it is too alkaline and there is not enough soap in the mixture. On the other hand, I’ve had someone tell me that the washing soda and borax ARE soap. Do you know anything regarding these comments I’ve received? Also, how has the soap worked for your clothes and your washing machine?”

I have wondered some of these same things myself so let’s dig a little deeper into the chemistry behind our homemade laundry soap and see if we can answer some of these questions.

Why do we use soap to clean laundry?

Soap is used as an emulsification agent. Oil and grease are not soluble in water, meaning they do not dissolve. As most of us know, oil and water do not mix and will separate if we try to combine them. If we want to remove oil or grease from clothing, the oil or grease must be made soluble. Soaps work to emulsify oils by “bridging the gap” between the molecules of water and oil, allowing the oil to be rinsed away with the water.

Are washing soda and borax a type of soap?

My understanding is that washing soda and borax are minerals, not soap. The minerals help to soften the water which allows the soap to work better, and also is very effective in neutralizing odors. Minerals also function as laundry boosters as they can help brighten clothing and keep it from graying.

What about alkalinity?

Substances are categorized as either alkaline (base) or acid using a ph scale that goes from 0 (acid) to 14 (alkaline). Pure water has a ph of 7 and is considered neutral. Some examples are vinegar which is very acidic and has a ph of 2, and bleach which is very alkaline and has a ph of 13.

Washing soda has a ph of 11 and borax has a ph of 9 so they are both alkaline. Most soaps are alkaline too however some soaps like Ivory, or glycerin or castile soaps, are not as much so.

How does alkalinity affect my laundry?

The chemistry here is that a stain that is acid based or protein based needs to be neutralized with an alkaline substance. A stain that is alkaline based needs to be neutralized with an acid substance. The two ends of the ph scale cancel each other out. My research so far seems to show that most food stains fall more into the acid based area and therefore alkalinity is the more needed substance to counter-act it. Examples of alkaline stains are grass stains or rust stains which is why they might tend to be such stubborn stains.

OK, there’s some background chemistry. Let’s get to the heart of Valerie’s questions:

Does she have enough soap in the mixture?

I have also wondered about this. I have been going on my first batch this whole time and only last week made a second batch. I decided to add a second bar of grated Fels Naptha to see if it made any difference, although I was not really dissatisfied with the first batch. I am in the process of just starting to use it and test it out and I will share more about that once I have used it a little longer.

If your laundry is heavy on food stains (most likely because you have children), you will probably want a higher soap ratio. I would think Valerie’s three bars of Ivory are sufficient. The primary role of soap is to help lift out oil and grease.

Will the mixture not work because it is too alkaline?

I have seen no evidence of this. In fact I have found this mixture to be great at neutralizing odors which is a primary function performed by the washing soda and borax which are alkaline. My research has indicated that almost all soaps and detergents are alkaline.

Homemade Laundry Soap

How has the big batch powdered laundry soap worked for me?

I like it! I should make it clear, however, that I am doing laundry for just me and hubby and it is not heavily soiled laundry like when you have small children. I have an old washing machine, and this mixture has had no adverse impact on it at all.

Perhaps the only thing I have wondered about is if it is fading bright clothing. I had one very bright blue sweatshirt jacket that seemed to fade after I used this soap. My sister-in-law also thought she noticed this on some clothing too. This could be the case as the mixture is heavy on the minerals that perform the laundry boosting function of brightening. I’m wondering if the “brightening” is translating to “fading” on a very colorful piece of clothing.

A quick summary, please . . . .

The pros?  This mixture freshens laundry, is great at neutralizing odors, has laundry boosting minerals for brightening, is an easy recipe to remember, and lasts a long, long time. I have been happy with it although I am currently testing increasing the soap ratio.

The cons? It might not have enough soap in it to lift out heavy stains. It might also fade bright colors. I am not sure if this has to do with alkalinity or with the other properties of the washing soda and borax.

Whew! Hopefully you are still with me and your eyes have not glazed over yet! There is one more subject I want to explore but we will give our brains a rest and save that for the next post. That subject is the difference between a soap and a detergent.

I freely admit that I am still on a learning curve on this whole subject. I welcome your comments, advice, and stories.

Click here to see more of my – – > Homemade Laundry Recipes

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  1. Just measured the “rice pantyhose” in my dry dish washing detergent (which is in a gatorade bottle) and it is only 1/8 cup of rice. I just leave enough room in the pantyhose when I tie it off to wiggle it down into the container. I’ve used the same rice hose for over a year now without putting in a new one. No clumping.

  2. For those that have clumping issues, here is what has worked beautifully for me: Use a knee hi or cut off section of pantyhose, add white rice and tie. Add this to your container. Give container a shake once in awhile. You don’t need a lot of rice in the pantyhose. In fact I probably have about 1/4 cup in my homemade dry dish washing detergent and about that or a little more in my container of dry laundry soap. It helps draw out any moisture and keeps your detergent/soap clump free! ๐Ÿ™‚

  3. I’ve used the homemade laundry soap for years with 3 bars Pink Zote grated, 2 boxes of washing soda, and 1 box Borax. Yesterday after making some more I had to soak a greasy napkin, this morning when I went to take it out of the water (I had a tablespoon of my laundry soap in the water) it was evident that it had removed a lot of the grease, it was sitting on top of the water. I was pleased with that.

  4. I do all my wash in cold water except whites and it dissolves just fine but I do use a food processor and a coffee grinder to make it an ultra fine powder that I tested in the kitchen sink for dissolving and it does better in hot water but does just fine with cold as well. I did notice that after the detergent sits for a few days it “clumps” slightly but I just use a wire wisk to manually re-mix and that seems to do the trick but in my experience all dry detergent “clumps” over time so it’s no big deal to just go ahead and mix it up again.

  5. I do almost all of our wash in cold water and have no problem. Once in a while i will wash with hot (whites, mostly), but it is a rare occasion thing. If the borax or baking soda is really lumpy (big lumps) it doesn't all dissolve, but i try to crush out the lumps and generally don't have a problem.

  6. Jan – I almost always use a warm water wash and a cold rinse with this soap so I'm not certain how it would work with a cold water wash. However because this soap seems to dissolve really fast in the warm water, I would think it would dissolve pretty well in cold water too.

  7. Kathryn – I love your “long winded” comments. I always learn something! I think I better move my borax out of the damp basement and into a better air tight container too. My borax is also turning into a brick if I don't use it fast enough.

  8. Terre – I'm finding that I like to keep both the powder and the liquid on hand. The powder is really convenient to just scoop out and toss in. I've also noticed that as soon as I toss it into the washing machine water, that it dissolves and disappears into the water really, really fast. (There are no suds with this mixture). This makes me think there shouldn't be build up in the pipes, but I guess I can't say that for sure.

    My borax is hardening up too! I keep mine in the basement which is damp – maybe a bad idea per Kathryn's comment below.

  9. I've read about making your own laundry detergent before (Trent at The Simple Dollar wrote about it a while ago; his recipe is similar to yours and he uses whatever soap he has on hand, he has 3 small children). I was already using another alternative, but would do this had i not already switched.

    If you are worried about fading of clothes, wash them inside out.

    I use Soap Nuts, baking soda and borax. (Baking Soda vs. Washing Soda Washing soda is not easily available where i'm at. Baking Soda is not as alkaline, but does a fine job for our adult-only household.) I sometimes add vinegar to a rinse of towels or sheets. My MIL says they are quite soft. I do use the Fels Naptha on stains, and it is wonderful! It will even take out stains that have already been thru the washer & dryer.

    I've not noticed the fading in color very much. (Even commercial stuff fades, depending on the fabrics. I had black pants when i used to use Tide, or whatever – i don't even remember now what i used to use – and they got quite faded. I should have washed them inside out.) It doesn't do an absolute perfect job. I make my own deodorant (for health reasons rather than frugality), and it is oil-based. The underarms of my shirts tend to get a bit grimy. I could use the Fels Naptha on them, but i guess it isn't that important to me. Commercials tell me my life isn't complete without sparkling clothes, but i live with “good enough.” I don't have other stains or odors, the clothes are clean, and that's enough.

    Terre – do you live where it is humid? I think the tendency for things to harden the way you describe has to do with the moisture in the air being absorbed by the product. Where we live is very dry, and i don't usually have problems with borax hardening. You might be able to get around this by making smaller batches and keeping it in an air-tight container. I think commercial products have anti-caking fillers to prevent this, but they probably don't help your clothes much.

    Sorry i'm so long winded.

  10. Do you like it as much as the home made liquid? I have also read that those batches sometimes harden over time like brown sugar tends to do. I know that if I don't use all of my borax it will become a brick. I have been wanting to try the powdered but another fear I have is that regular store bought powdered laundry soaps don't dissolve well and tend to over time cause a build up in pipes and that can end up to a bigger cost that clearly out weighs the savings. I love how you do a really complete post when you post “make your own's. ” Keep up the great work!