How Not To Use Castille Soap

by Lisa Linderman on April 12, 2011

in diy,penny pinching,pioneer home skills

I’ve been making my own laundry detergent for a while now.  I’ve tried a powdered formulation, and while it’s much easier to store, I much prefer the results of the liquid variety, and will be returning to that as soon as I run out of the powder I made…which should be in about 2014.

I recently got interested in figuring out how to make a cheaper, homemade dishwasher detergent as well, and started doing some research.  Many recommend Borax and Washing Soda in equal parts, followed by white vinegar in the rinse aid dispenser.  Although Borax isn’t terribly dangerous, it is mildly toxic and can be fatal if ingested, especially by young children.  I feel weird about putting it on my dishes on purpose, even knowing that it will be washed off, so I went looking for a Borax-free recipe.

I was surprised to find that most “dishwasher detergent” recipes call for combining Castille soap (such as good old wacky Dr. Bronner’s) and vinegar, often with the addition of tea tree oil and/or lemon juice.  Excuse me?  Soap is very alkaline and made from fatty acids plus a very strong alkali (like sodium hydroxide).  Vinegar and lemon juice are acids.  What happens when you put them together?  Well, nothing blows up, but your dishes don’t get clean, that’s for sure.   What happens is a process which is the reverse of saponification, which is how a fatty acid is combined with a strong alkaline to make soap.  This  means basically you’re reversing the process that made soap in the first place, and you wind up with lumps of creamy white fat suspended in liquid.  Yay.  Ew?

I’ve seen some articles that say, “Just keep mixing if you get white globs.”  Well, the white globs won’t go away, they’re fat.  Another said they strained out the white globby stuff and used the liquid.  Except that the liquid is no longer soap, it’s vinegar, water, and oils.  Ew.  Not good for cleaning.   Another said that duh, you have to use HOT water or it won’t work.  Well….that just means the fat liquifies.  Once it cools, the white globby bits come back, as noted in that same article.

I thought I would demonstrate exactly what happens, and that this doesn’t mean you did it wrong.  It means the recipe is wrong. Don’t combine castille soap and vinegar.  You could potentially use castille soap as your “dishwashing detergent” and vinegar and lemon juice in the rinse aid dispenser, but using soap in the dishwasher isn’t recommended either.  There’s a difference between a detergent and a soap.  Dishwashers are meant for use with the former, not the latter.  Typically, so is your washing machine.

First, I took a small glass and added one part vinegar, one part warm water, per the basic recipe I keep seeing repeated.  The bottle to the left is Dr. Bronner’s Peppermint Castille Soap.  The labels are wacky, the soap is good, and it gives me flashbacks to Nerd Camp when I was a kid.

Doctor Bronners

Doctor Bronner's Peppermint Soap on the left, vinegar and water in the glass.

Second step, add a few drops of Dr. Bronner’s to see what happens.  Almost immediately, a cloudy white precipitate forms, and a scum forms on the surface of the glass.  Ew.  Nasty.  It’s like the crusty layer in a bathtub if you use too much soap and let it kind of sit.  Gross.

First precipitate

If you're not part of the solution, you're part of the precipitate.

Then I added the full amount of Dr. Bronner’s that would be called for, proportionately, to make a batch this size.  It was like watching cottage cheese form from nowhere.  Really yucky.

cloudy white mess

Dishwasher detergents should not be chunky like cottage cheese in bathwater.

Finally, I stirred it up a bit, as per the instructions on the one blog that assured people it’d be just fine if they “stirred it up a lot.”  I did stir.  What happened was that all the little fatty globs got together and made one big glob.  I pulled some out on the spoon, and for science’s sake, I poked at it with a finger.  Felt like very runny Crisco.  Definitely fatty, greasy.  I actually had to get some dishwashing liquid to wash it off my hands.  That’s not gonna work well to clean dishes!  I also stuck my finger in the leftover liquid.  Oily, but not soapy feeling.  And it doesn’t act like soap in water anymore, either.  Ew.

fatty acids

This will not get your dishes clean. Gross.

Final verdict: Don’t try this at home.   I haven’t yet tried Dr. Bronner’s alone or followed by a vinegar rinse in the dishwasher, but this is definitely not the way to go.   And hopefully it goes without saying that this won’t make a good concoction to clean windows, or floors, or anything else, either…

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Homemade Dishwasher Soap Disaster #1 | His and Hers Homesteading
May 28, 2011 at 8:03 am


Courtney May 25, 2011 at 6:57 am

Well I stumbled upon you bog because I followed the recipe seen online and ahh haa I made oil globs too! I am discouraged because I really wanted this to work and I don’t want to use borax. I think I will just try Castile soap with citric acid and water. I know it may not be the best but we’ll see. Do you have any new ideas?


Lisa Linderman May 25, 2011 at 6:36 pm

I was also looking for a recipe that didn’t use Borax, and most call for equal amounts of borax and baking or washing soda (they are not the same, but apparently either will work.)

Bear in mind that if you use Castile liquid soap mixed with citric acid, you’re going to get the same globs as if you mixed it with vinegar, because it’s a chemical reaction between the soap and the acid. If you use the citric acid in place of the rinse agent, it should be fine. (I use vinegar as a rinse agent.)

I’ve given up and gone to the least-expensive eco-friendly dishwasher detergent I could buy commercially. I haven’t found any other good option. Good luck!

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