One of my favorite ways to save money is by making my own homemade laundry detergent. However there’s one thing that kinda Flusters me about it, the Fels-Naptha Soap is always so coarse. I use both of the blades in my food processor, but I can never get it chopped up fine enough.
The other day when I was perusing Pintrest, I came across the Microwave Ivory Soap experiment. I’ve seen the pin many times before as I’m sure you have, in fact, I even tried the experiment with my kids. It wasn’t until the other day that a light went off in my head, I wondered if microwaving a bar of Fels-Naptha soap would work as well as it does with the ivory soap.
Luckily, when I got this bright idea, I was beginning to run low on my laundry detergent and it was time to make a new batch.

I’m please to report that it worked pretty darn good. The only difference is that the Fels-Naptha doesn’t grow and become as flaky as the Ivory soap does.
Ideally I would have loved for it to be flaky, that way I could have eliminated having to use the food processor, but you can’t have everything.
*Bonus – my microwave smelled fresh after microwaving the soap.

Microwaving it really eliminated the density of the soap, see all of those lovely little air pockets?
Those air pockets are what made it really easy to get a fine grate on the bar of soap.

Before, I would have to use both blades of my food processor to break up the bar of Fels-Naptha and it sounded like I was trying to grind rocks. Now I only have to use the chopping blade and it so much easier on food processor.
*Bonus – I only have to clean the chopping blade now which is a lot easier to clean than the shredding blade is.
You can see the difference that microwaving the bar of soap before putting it in the food processor does from this photo. I’m really pleased with the results.
Yay! The Fels-Naptha for my homemade laundry detergent isn’t as course now and my Fluster has been Busted!!!!
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Hi Robin, this is so interesting and love how you solved your dilemma. Thank you for stopping by for WWAW. So nice to meet you. Wishing you a Happy Easter.
Hugs
Hmmmm I've used Zote soap for mine (same recipe otherwise) and it expands and makes a huge mess. So, Fels Nappa does not do that?
All soap will expand, I put it on a paper plate, it doesn’t get bigger than that.
My zote did not expand in microwave. It melted into a creamy mess. Any suggestions?
I’ve never tried putting zote in the microwave. Maybe use the microwave zote to make a liquid laundry detergent.
It does work. You need to cut soap up into small squares. Place a few squares on plate at a time. You didn’t microwave it long enough. Try 2 mins it should expand. Add on more time if needed. You know if needs more time it will be mushy so throw it back in microwave. Careful don’t burn yourself mushy stuff will burn you. If you have some still suck on plate throw back for couple mins until it expands so won’t go to waste. Try putting 1 square in first to see how long it takes for it to fluff up. Remember if it’s mushy you just need to microwave it some more. Enjoy
How long did you microwave it for? A minute? I'd really like to try this since I HATE grating the Fels Naptha.
I didn't do it for a set amount of time. I just watched it and when it stopped expanding I took it out.
I just did this and it worked very good ground up so fine thank you
I love how fine it turns out doing it this way!
Omg…thank you Robin, love making my own detergent but always had trouble grating the bar of soap…this method worked like a charm..your a God send. Thanks so much for sharing your wonderful idea…Nancy B
Grating soap is the worst, I’m so happy that this worked for you.
BLESS YOU, BLESS YOU, BLESS YOU!!!!! I’ve been making my own detergent for years and have hated grating the Fels Naptha (my favorite). Arthritic hands are getting worse. And I’ve even microwaved soap as part of a Bible School lesson last summer. I never thought of it for this!! God’s love expanded a tad more….again in the microwave!!
It’s definitely a knuckle saver!
Do you know if this would work with Kirk’s Castile soap?
I really don’t know, I’ve never tried it! If you try it, let me know if it works!
That is my exact same question! Did you try it, and did it work with Kirk’s?
What is your detergent recipe ? Want to k ow if it is similar to mine? This is my first time. Lol thanks
Here is the link to our laundry detergent recipe: https://flusterbuster.com/homemade-laundry-detergent.html
That is so weird and repulsive lol, who grates soap for detergent.. in Australia you would be given mental health help
I guess I need to be fitted with a straight jacket. LOL I’ve been making my own detergent for years and the finer it is grated the better it dissolves in the wash.
Why would you find it necessary to make such a rude comment? If you don’t want to make your own detergent, go to another page.
If you microwave it a little longer, like 2 minutes per bar it will be soft enough to crush by hand.
This is so funny, i have always microwaved my fels naphtha and always such a pain. It makes the microwave smell of fels naptha which isnt good for later when you cook food in there. I even bought a used microwave off of marketplace to use exclusively for soap cooking (lol). Today for first time i read about grating your soap and then running in food processor to make it fine. Well i grated it with the grating disc and then ran it with the regular blade and it seems pretty fine to me? We shall see!
Enjoy the microwaving!, i used a rolling pin to break it up never thought of my food processor..sheesh. Regardless of how you do it, it’s good soap
When I microwave the Fels Naptha I put a bowl over the top, it seems to cut down on the smell. It really is good soap!!
Wow! Thank you for the microwave tip. I dreaded having to grate the bar. It made such a mess and I could never grate it fine enough. THIS METHOD IS PERFECT!
It will leave your microwave smelling really fresh. I use a cheap microwave that I bought at a yard sale.
I use 4 bars of Kirk’s no-fragrance Castile soap in a batch of laundry detergent. I microwave each bar for 30 seconds, grate it with a box grater, then move on to the next bar of soap. This helps immensely to speed up the process.
It works way better if you cut soap into 6 small squares then microwave it. Only do a few small squares at a time, tiny squares of soap really expand. (I love watching soap expand on microwave, so satisfying!) Let cool then either grate, process, or just crumble with hands.
I add some borax and washing soda to the soap chunks in a food processor. It grinds nice and fine with those additions, and they are part of my recipe anyway.
Do you use your regular food processor or a separate one dedicated to soap grinding?
Yes, because the Fels Naptha is a soap. Just be sure to scrub the food processor well before using it for food.
Looking for another way to make bar soap easier to grate that doesn’t involve a microwave since they are unsafe.
A food processor with the grater attachment would be the easiest way!
Your website has so many ads populating that it moves the page and I can’t even read the article.