I know this has been done before, but I thought I would document the latest batch of soap I've made. Hopefully this instructable should give you some practical hints as well as help you with the theory of making soap from leftover fat.

Soap makes a unique and personal gift, especially when it is home made. You can also sell your soap at a farmer's market or just use it yourself. And it's a great way to get rid of old grease and fat that would otherwise find it's way to sewers or landfills.

The process uses caustic chemicals, so it is slightly dangerous. But if you follow general safety guidelines and keep your wits you should be fine. You might make a mess, but it should be easy to clean up because most of the spills will be made of soap!

I got most of my info from this page and this lye table

I was inspired by this instructable:

Note: I would've gotten better pictures, but it's hard to use a camera with eye goggles and rubber gloves.

Step 1: Supplies

Ingredients you will need:
1. A lot of animal fat or vegetable oil.
2. I added some olive oil to my recipe to make it milder.
3. Lye (NaOH) crystals. You can get this at the hardware store next to drain openers.
4. Distilled water. You can use tap water, but I wanted to make sure there were no dissolved minerals that could ruin the soap.
5. Essential oils for a scent. This is optional, but I think it helps. I use tea tree oil and jasmine oil. You can find these at a natural foods or drug store.

Tools you will need:
1. Safety equipment: Rubber gloves, goggles, and an OPEN bottle of vinegar withing easy reach, in case you need to neutralize any spilled lye. Lye (NaOH) is very basic and caustic, and it WILL burn your skin, or any part of your body for that matter. If you've ever seen Fight Club than you know what I mean.
2. A large glass or ceramic bowl to mix everything in. Anything that touches lye must be glass, because lye can react with plastic, wood, and especially metal. I was lucky enough to find a big Pyrex bowl in my attic that an old roommate left behind.
3. An accurate scale. It doesn't matter whether you measure in grams or ounces, but you must be accurate. I have a digital scale that works in grams or ounces.
4. Something to stir with. You can always just use a big spoon, but it will take a long time and you will get tired quickly. I got a stick blender at Goodwill for a couple dollars that worked well until the motor burned out. So for my second batch I just pulled it apart and mounted the business end to a power drill. Make sure that whatever you use for mixing, you wash it very well before using it on food. I have dedicated equipment that I use for mixing soap and nothing else.
5. Some kind of mold to pour the finished soap into. Besides a casserole pan or plastic bin, you can also use lengths of PVC, or paper cups to mold the soap into round shapes (see the main photo).
6. Notepad and pen along with a calculator to make conversions.
7. You will also need a few more tools like bowls and scrapers etc.

Lay down some newspaper on a big table or counterspace. You will need plenty of room to make soap.
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ThomasP57 months ago

I found these directions from 1833 on how to make soap.

ThomasP57 months ago

If you are interested in making soap you should checkout http://epic-soap.com/

The Walton Feed soapmaking link has moved. It's now here: http://www.rainydayfoods.com/blog/soap-making-recipe-for-beginners/
mrmerino3 years ago
Hey, do I have to make this in an abandoned house?
I am really interested in making my own soup but i am not sure that i will be able to get Lye (NaOH). Is it necessary or would it be ok to skip it?
If you are indeed making soup, then you should definitely skip the lye!
Rikitiki3 years ago
This is a good idea.
Calis5 years ago
Please don't use vinegar to neutralize lye on your skin.  While it will neutralize it, it also causes a chemical reaction that releases a great deal of heat.  This can cause thermal burns on top of your chemical burns.  If you get lye on your skin,  brush it off with a dry gloved hand, or wisk broom or..you get the idea.  Then rinse the area thoroughly with water.
abadfart Calis5 years ago
his name is Robert Paulson LOL meatloaf  
his name is robert paulsen... his name is robert paulsen...
lol im watching that movie right now.
very nice i use fight club a a test for new girlfriends
HEY! First rule!
that...sounds a little creepy :D
haha well if they like the movie then there chances go up... the girl im seeing right now quoted it the first time we met so i knew she was a good choice
PhylC094 years ago
I also make soap and sell to make extra money and I use good old shortening in 35 lb blocks from restaurant supply. For home purposes, the one pound blocks of shortening or lard works fine. Some shortenings are blends, which also include beef tallow.
It makes a great soap and I like to add other ingredients to make it hard, but it's not necessary for home use. Just make sure to use coconut oil and olive oil (not the extra virgin), it's what makes the soap later well. Here are some links for other info: http://www.ziggurat.org/soap/

Happy Soaping
nax5 years ago
I almost lost my house cleaning fat yesterday. I'd done the boil it and then scoop off the fat three times, and I was melting the clean fat to make the soap. A bubble of water hit a hot spot in the fat and popped hard. Fat everywhere, including the stove - huge grease fire. I was lucky, the grease fire went out by itself soon after I turned off the heat. Lost about half my fat, which was a coffee can full. Spent most of the day cleaning it off the floor, walls, and ceiling. I am not joking about the ceiling.
discontinuuity (author)  nax5 years ago
Sorry to hear about that. I have an electric stove so I hadn't thought of the fire hazard. I usually boil in a tall stock pot with a lid to minimize any spills or splatter, and melt fat in the microwave.
I probably would have been fine if I had kept stirring. The tall stock pot is a good idea too.

Not so sure about the microwave - I know people who have had candle wax ignite in the microwave. But if you keep the bursts short and pay attention you should be fine.

I tried again the next day using vegetable oil, and it looks fine so far. Still has to age before I know how good it will be.

All's well that ends well. I got divorced the day before the mishap and I felt like I didn't care about anything anymore. Turns out I care quite a bit about flaming death and destruction. Got my emotions back online. Effective, but not recommended.
Neat. Looks like messy work kind of, but it's worth it!
discontinuuity (author)  GorillazMiko5 years ago
It cleans up pretty easily, because all the mess is just soap! Laying newspaper down on your work table helps a lot though.
SoapyHollow7 years ago
I don't know where you got the idea that vegetable oils can't be used for soap. I've been making vegan safe vegetable soap for years and years. It makes a much better soap than those with animal fats; it lathers better and is better for your skin. (As well as being safe for kosher, halal and vegan lifestyles.) The oldest soap company in the world has been operating in Palestine since the time of Christ, and they make Castille soap, which is olive oil and palm oil. Animal fats in soap are a relatively recent tradition, starting in the early 19th century when large amounts of animal fat were available to the common man. Secondly; NEVER EVER add water to lye. You add lye to the water. Also, using glass for the NaOH and water blend is a bad idea for anything but very small batches. Glass tends to crack. Your best bet is stainless steel all the way around. For the record; coffee grounds make a fabulous addition to soap. You have to grind your own, but my Coffee deodorizing soap is a huge seller. It is significantly better to cure traditional soap in open air, or like we do, in dessication cabinets rather than wrapped, especially using animal fats.
discontinuuity (author)  SoapyHollow6 years ago
I stand corrected. Some of the links at the top of the page (which now seem to have gone dark) it seems gave me some incorrect information. I'll be editing this instructable to be more accurate, and when I make my next batch of soap (probably some combination of olive/palm/coconut oil), I'll make an instructable about that too.

The only real reason I've been making soap from bacon fat is that it is free and abundant, and makes some pretty good soap. And because I saw this instructable before I made mine.
Waltonfeed web link changed, new one is below.

discontinuuity (author)  drawe215 years ago
Thanks, I updated the link.
Yeah...I didn't mean to sound as bitchy as it does when I re-read it. Soap is a bit of a passion for me, and like all geeks, I get weird about my subject area. ;)

I've got a good small batch recipesmall batch recipe in the instructable that I used to make little "cake" soaps, but the recipe works in any mold. Alternately, I'd be glad to share recipes with you, or help you fine tune something if you ever want any help. :)
discontinuuity (author)  SoapyHollow6 years ago
Not bitchy at all. I appreciate your knowledge, since most of mine seems to be apocryphal and based on old wives' tales, or something I read once and half remembered. My next batch of soap is still a ways out (I've got other projects to deal with), but I will definitely consult with you before beginning. I would like to make a few pounds to sell at the local organic market, to see if I can make some spare cash from selling soap
I've had a soap company for a long time, and we recently had to stop selling because of insurance issues. There was only one company in the country that would underwrite product liability insurance for small manufacturers at a reasonable price, and they decided that after reviewing the new legislation that is about to impact companies like mine, to more than quadruple the rates...bringing my insurance rates close to what I actually *made* each year.
(here's a link to stuff I've written about the pending federal legislation )


We have yet to be able to find another underwriter, even though there has never, in the history of tort system in the US, ever been a successful claim against a soap manufacturer due to product liability.

But, this being America, land of the courtroom land shark, it's absolutely insane to sell anything without insurance.

I tell you all of that, because liability insurance is one of those things you may want to consider. Without insurance, if someone slips on a bar of soap, and decides to sue you, they can bankrupt you in legal fees alone before a judgment ever gets rendered. All personal assets are up for grab unless you're a corporation, and even then, they can try to attach personal assets of owners and board members. The tort system is crazy and only the lawyers win, really.

The odds of anything happening are really low. But, for me, I couldn't take the chance, so I stopped selling until I can find insurance. Unfortunately, that meant putting everyone who worked for me out of a job too, and then that rolls into my suppliers needing less people and warehouse space, etc.... The system really is stacked against small businesses.

Just something to consider.

please tell me the ingredients for vegan soap my mail id is vasudevpbhat@gmail.com thanks for your most valuable info
noname4205 years ago
LMFAO well Tyler Durden says "Hi." Sorry i saw the warning you are not held responsible for the actions of us and or our imaginary friends to make homemade dynamite is classic. I wonder how many other people got that joke. The first rule of project mayhem is don't talk about project mayhem.
discontinuuity (author)  noname4205 years ago
Sorry, I can't talk about that.
taluntain5 years ago
would i be able to use fat that a slaughter house just throws in the trash
discontinuuity (author)  taluntain5 years ago
Yes, just be sure that it isn't rotten, and you know what animal it comes from.  Then you will need to cook down all the fat until you get clean lard and use it normally.  Although if the slaughterhouse is throwing it away it might be nasty already.
not always i used to work in one and if the cow is to fat they cut off extra fat to make the meat leaner
abadfart6 years ago
nice fight club joke
good idea. but still either way your reaction is going to heat up. it simple chemistry. there will be a set amount of energy released. now how that amount of energy is dissipated over time would depends on the temperature. but i usually heat my fat up anyways. helps catalyze the reaction.
Yes, you want to keep it warm, since cooling the mixture might make the fats solidify before they've fully reacted.
CherryPie7 years ago
Anyone know how to do this using wood ash to make your own lye?
discontinuuity (author)  CherryPie7 years ago
Dead link.
it may be my moms crappy comp but i think its a dead link...
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