The Lye to Fat Table
Soap making is not hard to do if you are armed with just a little bit of information. Read this page carefully and you shouldn’t have any problems.
Water: For best results, use rain, distilled or soft water. You should generally use 6 oz of water to 16 oz of fat. Another way to figure the same thing is: water wt=fat wt X 0.38. Don't worry too much about getting it exact, however, as this measurement isn't terribly critical.
Lye: You should know a little bit about lye, sodium hydroxide. Lye is a very strong base and if you get it on you, you will find it's bad stuff. (Be sure to store lye where kids or pets can NEVER get at it.) You must use care in determining what utensils and mixing containers you use when handling lye. Use wooden or plastic spoons and enameled, plastic or glass bowls for mixing. (Lye will eat up Aluminum in a hurry. Also, lye instantly and permanently takes the shine off Formica. Formica is so sensitive to lye that it left timeless streaks across the table where I wiped a few dry crystals off with my hand. Now, with our table top and kitchen counter top ruined, Brendy ushers me outside when I mix my lye.) You would be wise to wear eye protection and rubber gloves when handling the lye crystals or the lye solution after you have mixed it into the water.
Dissolve lye in cold water. Never pour the water into the lye or it could possibly explode all over the place. If you don’t stir it immediately as you pour the lye into the water, the lye will settle to the bottom and quickly solidify. This isn’t a problem as tapping it with the stirring utensil will break it up. As you mix it a chemical reaction takes place between the lye and the water, heating it up. If you are making a large batch of soap, the lye can possibly start the water boiling - with little droplets of lye water splattering all over the place. If this starts happening, stop stirring it until the bubbling stops. Generally, it doesn’t take more than a minute to dissolve the lye crystals in the water. You know this has happened as the water will become relatively clear. The lye water will now have to cool below 100 degrees F before pouring in the fat.
Fats and Oils used in soap making. In my experiments I have learned almost any fat or oil can be used to make soap. Fats for soap making include animal fats such as tallow (fat from beef), lard (fat from pork), and the various plant derived oils. Traditionally animal fat has been used, with beef tallow making the best soap, pork lard in the middle, and chicken fat the worst. It's generally accepted that the harder fats make better soap.
There are a multitude of fats and they each bring their own unique qualities to soap. If you want to know what a particular fat will do, make a small batch of only that fat and see what it does. Armed with this knowledge you can mix fats to give your soaps the qualities you want. And this is how soap recipes are born.
Whatever type of fat or oil you use, you must ensure it is clean and free of impurities. It shouldn’t be rancid, have excess salt in it, or any solid particles.
Rancid and dirty fat can be cleaned by boiling it for a few minutes in a large pot with four parts water to one part fat. Set it aside and let it cool. After it has solidified, remove the fat from the pot in one piece. One way to do this is to run hot water around the outside of the pot, melting a thin layer of fat next to the pan. It should then slide out. Scrape all the foreign matter off the bottom of the fat. If it is still dirty, repeat the cleaning process again. It is also fairly easy to render your own fat.
What are your best fats for soap making? Amazingly, the soap making professionals feel that lard beats tallow and vegetable oils for gentleness to your skin. However, soap made with 100% lard doesn't lather very well. But it cleans beautifully. There is a predominant idea today that you have to get bubbles for the soap to do it's job. Soap making professionals have told me this is not the case. But if you want bubbles, you can have the kind of bubbles you want by using different oils.
Different Fats that create bubbles:
Coconut Oil gives big, fluffy bubbles. 100% coconut oil soap is sometimes used around maritime operations as it will even lather in sea water.
Olive oil gives very fine, silky bubbles.
In your soap making, use at least 25% of these fats as part of your overall fats to get the desired effect you are seeking.
Saponification (Sap) Value: Each fat requires a different amount of lye to change the fat to soap. See the Lye to Fat Ratio Table soaptable for a short discussion on this and a listing of different fats and the lye required to convert them to soap.
The temperature of the fat you pour into the lye water is important. It needs to be a bit above it’s melting point. This is 130 degrees F for beef tallow, or 85 degrees F for pork lard, or about the same temperature for vegetable oil.
Mixing: With the lye water and fat at the right temperature, gently pour the fat into the lye water. Stir gently, pulling the lye water up through the fat. This may take several minutes. You should insulate your mixing pot with old rags, etc, to prevent the fat from hardening before the process is complete.
Saponification and it's role in the mixing process: Simply stated, saponification is the name for the chemical process that happens between lye and fat as they turn into soap. It doesn't happen all at once, but actually takes days to complete. There are different levels of this process, and the most important one for you to know about is the "Trace" stage. This is the point at which your soap has thickened up somewhat. As you let the soap run off your mixing spoon back into the mixture, the falling soap stays on top and doesn't blend in, but leaves it's "trace" mark on top. Another way to know when trace occurs is it's thickness, much like the thickness of pudding after you have mixed it.
It can take a long time to get your soap to the trace stage depending on the type of fat you are using. The lighter the fat (or oil) you are using the longer it will take for it to trace. You can expect a wait of anywhere from 30 minutes for animal fats to several hours or even days for the vegetable oils. Does this mean you need to sit and stir your soap for several hours until it traces? I don't. After mixing it for about 15 minutes, I do other things and mix it back up every 15 or 20 minutes when I happen to go by it. (You may wish to set your timer so you don't completely forget it!) I say mix it back up because as it sits it separates into two or three layers of fat and lye. And this is why you have to wait for it to trace. At the trace stage of thickness it won't separate out into layers when you put it in your setting trays or molds.
A False Trace can happen when making soap with fats that are solid at room temperature, such as tallow, lard, or shortening. If the temperature of your soap mix drops below the melting temperature of your fat, it will start to solidify. As it does, your batch will start to thicken up just like it was tracing - but it's not! To prevent this from happening, be sure that the soap you are mixing stays above the melting temperature of the fat. In fact, the warmer your soap, the quicker it will saponify (one of the reasons I like to cook it). It wouldn't hurt to keep your soap up to around 115 degrees F to speed this process along a little more quickly. At 120 degrees F lanolin will curdle your batch.
Vegetable oils can also be used for making soap. These oils are liquid at room temperature and without employing a trick or two usually require many hours of mixing before they trace.
Trick 1: Use a blender. The more finely the lye and fat molecules are intermixed the faster it will saponify. Hours (and even days, sometimes) can be reduced by using a blender. Don't use an upright blender unless you don't mind millions of tiny air bubbles being permanently whipped into your soap. Use the hand-held type instead. With one of these, even your most stubborn oils should trace within 20 minutes. And you will get a trace with animal fats within seconds. Anyone who has sat around for hours stirring a batch of soap will be ecstatic with this.
Trick 2: Cook it. There are a couple of processes that I have developed myself yet are rather unorthodox. And this is one of them. If you don't have a blender, perhaps cooking your soap is for you. After it has cooled, pour or spoon it into the soap mold or tray and treat it like you would for the no-cook recipes. Even though it has been cooked, the chemical reaction that slowly turns vegetable fats into soap will take much longer than for soap made with animal fat that has been cooked. But I expect you will be just as pleased with your finished product.
When your soap has traced you can add
your superfatting, coloring and perfume oils.
Superfatting oil: When your soap gets to it's trace stage, the saponification process is around 90% complete. Fat added at this point makes your soap softer. There is a reason why the superfatting fat is added after tracing instead of at the beginning with all the other fats. If it was added at the beginning you wouldn't have any control over which fat or oil ended up as your 'free fat' as all fats would saponify together. This is presupposing you are going to superfat with a different fat or oil than you used to make your soap with. Exotic oils are generally used in superfatting. They are added at trace to give the benefit of their desirable qualities without having to use so much that it empties your wallet. A good rule of thumb is to use 1 oz. per pound of total fat used in the recipe. (That's one part superfatting oil to 16 parts total fat.) Let me list just 2 of the more common superfatting oils:
Avocado Oil: Feels very soft to the skin and makes an excellent shaving soap.
Cocoa Butter: Makes a hard bar. It smells and looks nice, but doesn't lather.
Coloring Dyes: Several things are used to color soap. Approved items are clays, mineral pigments and spices. You can get these items from soap supply companies. Moving back into the area of unorthodoxy again, I color all my soap with a piece of crayola. Be aware that crayola as a wax isn't approved for skin use. If you are going to use a crayon to color your soap, don't sell it. The Gov. will get upset if they find you. Just because it isn't approved, it doesn't mean that it's bad, however. After all, it's only wax! We eat tons of it in chocolate.
I melt crayola into my soap after it has traced. Don't be tempted to put your crayola in at the beginning as the lye will change it's color. You may need to heat it just a little bit to get your soap up to the melting temperature of the crayola. Even adding a crayon at this late stage of mixing, you may notice a slight color shift over time. I'm excited with using crayons for another reason. I've found that my 100% lard soap will lather with only a small amount of crayon in it. How much? About 1 inch of 1/4 in. diameter crayola per pound of fat. After a bit of experimenting, I've also found the same amount of paraffin wax, another non-approved substance for skin care, will do the same thing. When adding it, be sure your soap is above the melting point of wax, then mix your already melted paraffin well into your batch. You don't have to pre-melt the crayola as it melts much easier. And the cost? A piece of crayon or a little piece of paraffin is just about free compared to the cost of coconut or olive oil. It's also available just about anywhere.
Fragrance Oils: There are two types of fragrance oils, FO's (fragrance oils) and EO's (essential oils). An EO is made from a distilling process and a fragrant oil is a chemical fragrant that is steeped in alcohol. EO's are usually used in soap making as FO's have been known to seize soap, or turn it into a yucky ball that doesn't saponify correctly. EO's are much more expensive and harder to find than FO's. If it is an EO, it will most often say it on the label. You will also know it by the exorbitant cost. FOs can often be used safely at trace however. Make a small test batch first to see if your FO is going to work alright before making a big batch. Be aware that rose and cucumber FOs are notorious for seizing soap. If you want to use an FO that can possibly seize soap, you can safely use it during a rebatch.
The Setting Tray: Mrs. Mertz used a galvanized tub. Other old timers used a wooden box in the shape of a tray with a cloth laid in the bottom of it. The cloth was used to help remove the hardened soap from the tray. If you are going to use a solid tray, may I recommend plastic wrap instead of cloth as a barrier between your soap and the tray. But there is something even simpler than this. If you have any square edged, flexible plastic trays with lips at least as high as a bar of soap is wide, use this. (After the soap has hardened, a slight flexing of the tray will dislodge the soap.) When the soap begins to harden (1-3 days for the non-cook process), use a knife to section it into bars. After it has further hardened (3-7 days), remove it from the tray, and break it into bars following the knife marks made earlier. Even though your soap looks hard at this stage, it is far from done. There's a good chance it contains a bit of lye that should dissipate into the soap as the saponification process continues. This will be true so as long as you had your lye/fat ratio correct soaptable in the first place. Your soap will need to sit for 2-6 weeks, depending on the fat you used, to dry out and cure. Use litmus paper to test the lye content of your finished soap. Be sure to wash off any soda ash that has formed before testing. Soda ash has a high PH value. Your soap should be below a PH of 9 within 36-72 hours after it has traced. The closer the PH of the finished soap is to 7 the better. If your soap is over a PH of 9, let it sit around for a week or two. Hopefully as the soap continues to saponify the lye will get transformed and the PH will drop. Your soap should be below a PH of 9 before you use it. I may get some real flames on the following comment: If you don't have any litmus paper and you want to know if your soap is ready for use, taste it. Your tongue will tingle if there is still too much lye in it. Of course, you don't want to swallow this stuff. This was suggested to me as a possibility by Mrs. Mertz and also by a more contemporary soap maker who sells soap.
Final Curing and Storage: With the soap out of the tray (or molds if you have them), stack it up and set it in a warm dry place for at least two weeks. When it has fully cured, place it in a plastic bag or air tight container, and store it in a cool, dry place. You will probably notice a thin, white powdery layer on the outside of your soap. This is soda ash, and forms as a result of the carbon dioxide in the air interacting with the lye in the soap. This outer layer quickly washes off the first time you use it. "If this is a concern, cover your setting soap with plastic wrap so the air can't get to it. After saponification is pretty well complete, you can remove the air barrier to let your soap dry out." After all this, if there is still a thin layer of soda ash on your soap after it has cured, wash it off, then let the surface of your soap dry before storage.
Final Soap Making Tips:
My experience: The recipes I used left a lot to be desired. The instructions weren’t sufficiently detailed for me to really figure it all out and so I made several mistakes which I will now point out.
The first thing I had trouble with was getting the lye/water/fat ratio correct. Often the recipe simply said ‘a can of lye.’ Obviously, in yesteryear all lye cans must have been the same size. Not so any more. From analyzing several recipes both relatively modern and old, I find the lye to fat ratio in many recipes to be lye heavy. I suggest you figure the lye yourself using the fat to lye table soaptable before using a recipe. Then alter it accordingly when making your soap. Let’s not forget the 0.38 parts of water to one part fat by weight. (Water, lye and fat are the primary ingredients for all soap recipes I’ve found, and will make a good bar of soap all by themselves.) The fat to lye ratio does not have to be overly critical, however. You will end up with "soap" with fat/lye ratios from 2.4 oz (69gm) to 1oz (26gm) crystallized lye to 1 cup (8oz or 210gm) of fat. And you may actually want lye or fat heavy soap depending on what plans you have for it. Mix it:
2.4oz (69gm) lye to 1 cup (8oz or 210gm) of fat for really tuff cleaning jobs, like laundry soap. This is extremely lye heavy soap.
1.05 oz (28gm) lye to 1 cup (8oz or 210gm) fat for general hand soap
As far as 1oz (26gm) to 1 cup (8oz or 210gm) fat for a more delicate facial cleaner
Note: For those of you who do not have a way of measuring weights, my experience has been that 1 lb of lye (455gm) measures out to 1 3/4 cups (462ml). By volume, lye can weigh more or less depending on how tightly it is packed. Unless you find yourself in such unusual circumstances that you have no other option, use scales rather than volume measurements when measuring crystal lye.
Note: in playing around with the mixture ratio, I have gone as far as 6/10ths oz (17.3gm) to 1 cup fat (8oz or 210gm). This still made soap, but it was very soft and would probably go rancid if not used fairly quickly. The more lye in the soap, the harder it is. (One of my friends told me how before the days of the automatic washing machine, his mother always threw a bar of home made soap into the wash during her ‘manual wash cycle’ then pulled it out before the ‘rinse.’ The same bar of soap lasted several batches!)
The second thing I had trouble with was adding the different ingredients at the right times. I’ve created some real messes with this one. Here is a suggested order to add things:
Sugar (Sugar won’t dissolve if you try to add it after the lye, or fat or oil have been mixed in, and tends to separate out when the fat is mixed in. If you cook it, it separates out at about 300 degrees in the form of very hard, dark brown scales. After making several different types of soap, I wonder why anyone ever put sugar on the recipe list in the first place. I no longer use it, and only left it on the recipe page to keep it intact with what was in the book.
Salt (ditto) It may be of interest to know that the commercial soap makers use salt to separate out the glycerin which is a natural byproduct of soap making. Then they sell it as a byproduct even though by removing it, they reduce the quality of their soap.
Ammonia (I didn’t like this in my soap. It made it smell terrible until it finally all evaporated out - then there wasn’t any in the soap any more. It was a waste of 1/4 cup of ammonia.)
Mix all your fats together before adding them to your lye water
Fat or Oil
Lanolin (Lanolin, being oil based, mixes with the fat very nicely as you melt the fat in preparation for mixing it.
After Trace: All the following items are optional:
Ground Oatmeal (abrasive element)
Vitamin E This is an antioxidant, and acts as an anti-rancidity agent. Poke a hole in one end of the pill with a pin and squeeze it out into your batch.
Fragrance oils: To prevent the lye from eating up your perfume, you also need to add this as late as possible in the saponification process.
The third thing I had trouble with was getting it to set correctly.
Three methods of getting soap to trace have already been discussed. When I first started making soap I didn't know the first thing about "trace." Because of this, I had several failed batches until I developed a unorthodox way of setting soap that incidently is a lot faster than waiting for it to trace. This method will only work with fats that are solid at room temperature, like tallow, lard, and shortening. And you can't color or scent your soap if you do it this way as you should only add these things after tracing. Professional soap makers are leery of this method as they feel it is important to stir the batch to trace as it keeps the molecules moving. Yet I add this last method here as I have had excellent luck with it.
The Intentional False Trace: After all the ingredients are thoroughly mixed, set your mixing container in cold water and continue to stir, especially the sides and bottom. I use a big spatula to do this as the fat will solidify first on the sides and bottom of the pan. This solidifying fat must be remixed into the warmer mass in the center of the pot. As the mixture cools, continue to quickly stir it while the whole batch thickens. When it gets to the consistency of thick gravy or pudding, (trace consistency) pour it into your setting tray. The idea here is to get it so thick there is no way it can separate, yet fluid enough so it will flow. With it in the setting tray, put it in the refrigerator so the fat in the soap can continue to solidify. After it is cold, take it out of the refrigerator and set it aside. Unless you make the soap during very hot weather, it won’t re-melt and separate. After a day or two it is ready to be cut into bar sized pieces. Note: Don't get confused here. If you actually traced your soap, you shouldn't put it in the refrigerator. The refrigerator is only used when you thickened your soap in cold water before tracing.
Final curing: As mentioned before, it takes soap days for the saponification process to complete, then weeks before it has cured, or all the water has finally evaporated. My experience is that it takes about 1 to 3 days for the soap to set up hard enough to cut the soap in the pan into hand soap sized bars without it melting back together again. Check it once or twice a day. You don’t want it so hard you can’t run a table knife through it. After sectioning the soap in the setting tray, leave it in the pan to further harden 3 - 5 days. You want it to be hard enough so it will maintain its shape and not break up as you are taking it out of the tray. You can’t hurt it by leaving it too long, but if you take it out too soon you can accidentally break pieces off or put big cracks in the bars that will later break. When it has cured long enough, remove the now solid soap and break it up into bars from the knife marks made earlier. If you used a solid pan lined with plastic wrap, after the soap is removed, use your finger to smooth out the small grooves made by the wrinkles in the plastic wrap. (If you wait, it will be too hard and you won’t be able to do this.) It is then stacked up and left to further dry (cure) for two or more weeks.
Using It: Even mentioning this may seem like over kill. When I first used that initial bar of lye heavy soap from my first ever attempt at soap making, I rubbed and rubbed, and didn’t hardly get anything. But I soon learned that I was just breaking it in. After I used it a few times, it was much easier to use. If you have kids, to decrease their resistance to using soap ‘you’ made, break it in first then put it out for them to use. They will hardly notice the difference.