Making Soap from Kitchen Grease

by Daisy on 10/22/2008

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If you’re saying to yourself, “Ivory, I don’t wanna to BUY fat to make my soap. I have plenty of fat in my grease can!” then this is the post for you.

So, how do we turn icky, blech-y, Mr. Ivory-should-be-ashamed-of-how-much-bacon-he-eats kitchen grease into glorious, bubbly, clean soap?

a. Put half fat, half-ish water in a pan and bring it to a boil.

b. Remove from heat, stir, and add about ½ as much COLD water as before cooking. (I had a coffee cup of fat, and added a coffee cup of water to boil, so I added a half a cup of cold water at this step.)

c. Let it cool till the fat floats and is scoopable onto a plate. (Fridge or freezer speeds it up. Just don’t accidentally defrost your chicken breasts, K?)

d. If it still seems a little blech to you, do it again. I did.

(Cleaner second time, no?)

2. Weigh and melt fat.

3. Sprinkle the lye into the water and swirl.

[As I mentioned previously, the lye calculators say that for one pound of lard-ish fat, you need 6 ounces of water and 2 ounces of lye–I had 3/4 of a pound of grease after washing, so I needed 4.5 ounces of water (3/4 of 6 oz) and 1.5 ounces of lye (3/4 of 2 oz­). ]

4. Wait till both are not smoldering hot and pour lye solution into the fat.

5. Blend with immersion blender.

6. Stop when you can see where you’ve been. (called “trace”)

6b. This is the time to put in the fragrance, if you wish.

7. Pour into custom built soap mold. (HA!)

Let it sit a day and peel off the carton, slice, and cure for a few weeks.

Waa-laa! Soap. Any residual pork rind-y smells will be GONE when it cures.

**Note to self, if the economy goes to heck in a hand-basket, check crystal ball three weeks ahead so that soap will already be cured when the big one hits.

Self-Proclaimed Recycling Queen of October 2008—


SAFETY REMINDER: Lye is caustic–See our discussion of and links to safety for soapmaking here.

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This post has been so popular that we put a rush on the follow-up post Like Bacon for Candles.

{ 11 comments… read them below or add one }

Melissa April 20, 2013 at 8:45 pm

I didn’t see the answer to this anywhere else on here, and I’ll risk sounding stupid, but I’ll ask anyway. Doesn’t boiling the water and fat together make a huge mess with popping oil everywhere? I tried a recipe for making liquid soap (from scratch) that had me boiling water and oil together and it exploded everywhere and was very scary. I just don’t want to repeat that again. It was traumatic.
Otherwise, I can’t wait! I’m making my brother in law some soap for his birthday because he loves bacon and he’d be happy to know none of it was being wasted 🙂

acr May 17, 2013 at 1:01 pm

Melissa – I have been making soap for years and I have rendered my own cow fat into tallow.

I see several problems with the author’s instructions. It looks like she is using a smallish pot. I use a deep stock pot. Also, the boiling water is unnecessary. When you clean fat (which is what the author is doing), you simply want the fat to be melted. Boiling is unneccesary. Here’s what I do:
Heat roughly equal portions of fat and water in a deep pot. You don’t have to be precise. When the fat is melted, put the pot in the freezer. Fat floats, so you will end up with a layer of fat on top and a layer of water beneath. The stuff you are trying to get rid if will be in the water and also on the bottom of the fat cake. Discard the water and scrape off the bottom of the fat cake. Then I wrap the fat cake in a paper towel and put it in the freezer. I like to use a paper towel so any water remaining in the fat cake can dissipate.

Marie May 31, 2013 at 9:46 pm

I used your instructions, but my soap seems to be too slimy. What should I do differently next time?


AnieW November 14, 2013 at 2:20 pm

Great idea! I hate discarded the fat I collect.

Erica Sullivan June 24, 2014 at 12:55 pm

Hi there!
I just followed your instructions for rendering bacon grease and for making soap and it turned out great! I write a blog about all kinds of domestic/homesteading/random things, and I am working on a post about my experience making soap. I really want to give due credit for the instructions and also maybe bump some of my readers over to you! (its a small number, but still). Let me know if I can link to you 🙂

Daisy June 24, 2014 at 5:50 pm

Erica Sullivan–Glad it turned out! Sure, links are good.

dawn conner January 8, 2015 at 1:06 pm

I hope the ‘website’ info you wanted was where I saw this, ’cause that’s what I typed. ANY way, DO NOT, I REPEAT DO NOT put a really hot kettle or anything hot for that matter in your fridge/freezer. you fridge uses the freezer to stay cold. that’s how they work. if you upset the mechanics of the freezer w/ the heat from a hot kettle or ANYTHING HOT youre going to hurt your fridge/freezer. you need to wait til ‘whatever’ cools all the way down before putting it away to get really cold or frozen. wait til winter to do you soap, and stick it out on the front porch and let it freeze and/or cool all the way to cold. believe me you don’t want to have to call the repair man and tell him what you did to your freezer and then pay him X amount $100 for that repair job. especially not sears. they screwed me over a fridge that was still under warranty.

Pat February 8, 2015 at 1:29 pm

Can I use chicken and turkey fats collected after roasting? Can I mix fats from pork, bacon, beef, fowl when making soap or must it all be separate?

Daisy February 8, 2015 at 6:14 pm

Pat–I think animal fat is pretty much lard by any other name. Mixing is fine.

Gregg May 5, 2016 at 2:10 pm

Hello, Daisy.

I started making soap about seven years ago and have never looked back. I started making soaps with various types of oils and used an on-line soap calculator to determine the correct blends. I found your Kitchen Grease recipe about three years ago and, with one minor change (fresh pork fat), have been making wonderful soap since then.

I get ten pounds of pork fat from our local grocery store butcher. I render it down over about 8 hours in a slow cooker and then boil it a couple of times to yield about five pounds of wonderfully clear fat stock.

I use quart sized milk cartons (former whipping cream used as our coffee creamer) as my molds. When mixing the ingredients I wait until I reach trace before I add essential oils for fragrance and I end up with amazingly hard soap that produces perfect foam, cleanliness and soft skin.

Thank you so much for posting this easy and practical recipe!

Gregg May 5, 2016 at 2:12 pm

I forgot to mention – the pork fat is free. 🙂

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