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How to Make Soap

Posted By Suzanne McMinn On March 25, 2010 @ 1:05 am In Handmade Soaps,Primitive Crafts & Country Style | 52 Comments

Let’s make soap! Are you ready?

In this post, I’m going to describe both the cold and hot process methods. Both methods follow the same initial steps, diverging at the end. Home soapmaking is most often done today using the cold process method, but hot process is what was commonly used by our great-grandmothers. Both processes actually use heat. Even in cold process, heat is applied as the fats/oils are brought to the right temperature before combining with the lye mixture. The main difference between the two methods is that no external heat is utilized further in the saponification of cold process while in hot process the saponification is actually finished over a heat source–in the method I’m going to demonstrate, a crock pot. I’ve made soap both ways now and I far prefer the hot process method. The soap is cooked through and cured right in the pot before being placed in the mold. It’s non-caustic and usable as soon as it hardens.

I’m not sure why cold process is so popular today, but I think just the term “hot” scares people who are already scared of the lye. I’m going to demonstrate both–and you can decide for yourself! Please do not take this post as your single source of soapmaking instruction. This post is intended as demonstration, encouragement, and inspiration. Get a soapmaking book or three and learn as much as you can–then get to soapmaking. It’s fun–and easy, whether you choose hot process or cold!

Read more about the different processes of making soap and what goes into soap here: Getting Ready to Make Soap: Part 1.

See all about the scary lye here: Getting Ready to Make Soap: Part 2.

And find out all about the necessary tools and utensils here: Getting Ready to Make Soap: Part 3.

If you want to develop your own recipe or test a recipe you’ve found online, use a soap calculator: SoapCalc.

If you’d like to try my first recipe to make soap, here it is!

Vanilla Sugar Dreams Soap:

lard–22.4 ounces or 635.029 grams
olive oil–9.6 ounces or 272.155 grams
distilled water–12.16 ounces or 344.73 grams
lye–4.24 ounces or 120.195 grams
4 vanilla beans, finely chopped or ground
1 cup white sugar
2 ounces vanilla fragrance oil (optional)
2 tablespoons cinnamon (optional)

You will have an unscented bar if you don’t add the fragrance–you may prefer that. The chopped/ground beans by themselves will not add much fragrance, but they do add pretty and delicious-looking flecks to the soap. With the chopped/ground beans and the sugar, this recipe has a light conditioning quality and a moderate amount of suds with a lovely, creamy feel that is very soft on the skin. (I love it!) The cinnamon provides a very slight hint of fragrance, but like the beans themselves, not a lot. It adds a bit more of a scrubby quality to the bar and also darkens the soap. If you prefer a lighter, less scrubby bar with clearer flecks of vanilla, leave out the cinnamon. This recipe yields approximately 3 pounds of soap out of the mold.

Vanilla Sugar Dreams soap with cinnamon.

Vanilla Sugar Dream soap without cinnamon.

CAUTION: Wear goggles and gloves any time you’re dealing with lye and while handling the soap until it tests non-caustic with a pH strip.

Note: In the excellent book Smart Soapmaking by Anne L. Watson, the author describes a temperature method as a sign that your soap is ready to pour into the mold in cold process soapmaking. I’m going to include the temperature instructions as a backup to seeing trace as some people may find that helpful. Trace is actually quite easy to recognize. While temperature-taking of the fats/oils mixture and lye mixture at the point of combination (in cold process) is important, I don’t find continuing to test the temperature through the blending process useful and, in fact, it’s a little bit of a hassle and sometimes confusing if you clearly have trace but the temps don’t add up. It’s also unnecessary–but you may want to try it. I found the evidence before my eyes of trace to be far more helpful.

On another note, I found varying directives on the temperature at combining the lye mixture and the fats/oils in cold process. Anywhere from 90-110 F to 90-130 F. I went with 90-110 as my target range.

And yet another note: If you intend to make hot process soap, taking the temperature of the lye mixture and the fats/oils mixture before combining is not necessary and you may disregard all temperature instructions here as well as the lye cooling bath. You’re going to cook it all anyway. Other than the temperature-taking, cold process and hot process instructions are the same until you get to the end, at which point I give directions for finishing each method separately. Never taking the temperature AT ALL is just one more reason to make soap using the hot process method! However, it doesn’t hurt if you do control the temperatures before combining the mixtures. Since that is the only difference between cold and hot process before the end where they diverge completely, I’ve combined the directions up to that point. Just know that if you’re doing hot process, it’s not important or required–but you can absolutely follow the cold process temperature instructions right up to the point where you go on to cook it through for hot process if you want! Up to you.

How to make Soap: Cold Process and Hot Process

Step 1

Gather all tools, utensils, pH strips and other supplies including your molds. Prepare your work area. Along with a large crock pot, you will need a number of bowls and utensils for holding, measuring, stirring, etc. Do not use aluminum, tin, or copper. Use stainless steel, glass, or heat-resistant plastic for your bowls and utensils. For your pot, I recommend an enamel crock pot, though you could also use a stainless steel pot and, if finishing your soap with hot process, cook it on low over the stovetop. You’ll also need a good kitchen scale, a stick blender, and a thermometer. (You can do this without a stick blender if you don’t mind stirring for a longer period of time.) For your mold, use anything you like, but don’t use aluminum, tin, or copper in cold process. (You can use absolutely anything with no caveats if you’re doing hot process.) I’m using quart-size paper milk cartons as my molds in this demonstration–make sure these are cartons with a waxy lining, not the shiny, silvery lining some have–that’s aluminum and can’t be used in cold process. (You’ll need two quart-size milk cartons for this recipe. One will be filled completely, the other only partly.) If you’re using a wooden or other mold, line it with freezer paper cut to fit. Place the molds on a heat-safe surface and cover the surface with freezer paper to catch any spills while transferring the soap to the molds. If preparing for cold process, have several old towels onhand for incubating the soap in the molds.

You will need a pot large enough for your lye mixing bowl to sit in. This is your lye cooling pot. Fill it partially with water before you get started to prepare it for the lye bath. (The cooling bath is required for cold process only, but again it doesn’t hurt if you do this step in hot process.)

Step 2

Gather and weigh the fats/oils and additives. Soapmaking experts recommend taking your measurements in grams. I weighed everything using ounces with this recipe and had no problem.


Olive oil.

The additives–chopped/ground vanilla beans, sugar (and cinnamon, if using), and fragrance oil.

Step 3

Melt the lard in the crock pot. Once it’s melted, turn off the crock pot and add the olive oil. Let the mixture cool, testing the temperature as it goes down–you can take the crock out of the holding pot to speed the cooling if you want. The fats/oils mixture should be within the 90 to 110 F degree range at the time it is combined with the lye mixture. When the fat/oil mixture is down to 110, move on to the next step. (Return the crock to the pot, if you’ve taken it out, and put the lid on the crock pot to hold the temperature of the fats/oils steady while you prepare the lye mixture. Important: At this point, the crock pot is TURNED OFF.

Step 4

Measure the distilled water.

PUT ON YOUR GOGGLES AND GLOVES. Measure the lye. I measure my water and lye inside then take everything outside to mix. You may prefer to do everything, including measuring, outside.

Slowly pour the lye granules into the distilled water. NEVER POUR WATER INTO LYE. ALWAYS POUR LYE INTO WATER.

Stand back from the mixture so that you don’t inhale the fumes.

The mixture will be cloudy at first, then turn clear. Stir constantly until the mixture is clear and all the lye granules are dissolved.

At this point, I take the lye mixture inside for the lye cooling bath. You may want to continue with the lye bath outside. Place the bowl with the lye inside the prepared pot of cold water. You are NOT pouring the lye mixture into this pot. You are setting the pot of lye mixture inside the pot to cool it. Add a few handfuls of ice cubes. Test the temperature as the mixture cools until it reaches the 90 to 110 F degree range.

At this point, also test your fats/oils to see that they are still in the correct temperature range. If not, heat the crock pot briefly. The fats/oils and lye mixtures don’t have to be at exactly the same temperature, but you want each mixture to be within the 90 to 110 F degree range at the time they are combined.

Step 5

YOU ARE STILL WEARING YOUR GOGGLES AND GLOVES. Pour the lye mixture into the crock pot with the fats/oils. (Remember that at this point, the crock pot is TURNED OFF.) Stir briefly to mix the ingredients. If using temperature as a backup for recognizing trace, take the temperature of the combined mixture now.

Place the stick blender in the crock pot, making sure the blade is completely immersed in the mixture to avoid blending air into the soap or creating splatters. I use a fairly deep crock pot–it’s a 6-quart crock pot. I prefer to use a bigger pot so the higher sides prevent even accidental splatters from getting out. Just make sure whatever pot you’re using, with whatever size recipe you’re using, the stick blender can be completely immersed in the mixture while blending.

The mixture will turn opaque and become thicker and smoother as you blend it. To avoid burning up your stick blender, blend with it on for a few minutes, then turn it off and just stir with it. Then on, then off, as you watch for the mixture to come to trace.

What is trace? Trace is the stage in soapmaking where you can draw a line across the mixture and it will remain visible for several seconds before disappearing. (Sort of like when you’re making a thick gravy or a pudding.) You can draw a line with the tip of the thermometer. You can pull the stick blender out of the mixture and see if it holds a little glop where you pulled it up. Draw a circle in the mixture. You’ll see the difference very easily.

Instead of the surface instantly smoothing out, you will see the “trace” of whatever you’ve drawn through it. Depending on the fats/oils involved, trace can usually be reached with a stick blender in 5 to 10 minutes. Hand-stirring typically takes 30 minutes.

You can back up your determination of trace by temperature. If you took the temperature of the combined mixtures before you started up with the stick blender, take the temperature again. Saponification creates heat. If the mixture has risen by at least two or three degrees F, it’s ready to pour into the mold for cold process–or move on to cooking through for hot process. (If you wait till it rises over five degrees higher, the mixture may be too thick to pour into the molds for cold process, but you can still spoon it in, so you can’t really screw this up. If you’re unsure if you’re seeing trace, blend some more and check the temperature again. Probably by the second time you make soap, you’ll feel comfortable that you know what trace is and will lose all interest in this temperature backup method.)

This is the point where cold and hot process soapmaking completely diverge. If you want to make hot process soap, skip down to the hot process instructions. If you want to continue with cold process soap, carry on right here!

Cold Process Instructions

*CONTINUE TO WEAR THE GOGGLES AND GLOVES until the soap is safely in the molds and you are wrapping it up.

Once the soap has traced, mix in your additives and fragrance oil, if using. (You would also add any soap colorant now, if using.) Mix quickly and thoroughly.

Pour the soap into your molds (or scoop it out with a big measuring cup).

With the milk cartons, you can clip the tops together with clothespins.

Cover the molds, wrapping them, top and sides, in at least two layers of old towels. In cold process, the mixture is continuing to saponify while it’s in the molds. It will actually get hotter initially before cooling off. Wrapping the molds with towels helps hold in heat during this incubation period.

Your soap will be solid in about 12 hours and ready to be removed from the molds and tested in about 24. WEAR GLOVES when removing the soap from the mold. If using milk carton molds, just tear the mold off. To test, dab a bit of distilled water on the surface of the soap. Using your glove, smear the water around to make a bit of paste with the soap and test it with a pH strip. If your strip reads between 7 and 10, the soap is no longer caustic and is safe to touch.

Cut the soap into bars and set it out to dry and “cure” for about four weeks. As it cures, it will become milder and harder.

*Use a sharp, smooth knife or a special soap cutter to cut bars.

Hot Process Instructions

STILL WEARING SAFETY GEAR! Once the soap has traced, turn the crock pot ON. Set it on Low. You can stir the mixture up now, but it’s not necessary. Put on the lid. Leave it alone. Check it periodically for progress. There is no need to stir it unless it’s spilling over the sides–which will NOT happen if you’re using a large crock pot. Note that you did NOT mix in the additives immediately after trace as in cold process.

The soap will gradually take on a waxy appearance. The edges will appear dryer than the middle as they push up the sides of the crock pot. This is okay. The edges will start folding over toward the middle.

At this point, stir it up. It should look like waxy mashed potatoes.

Test it with a pH strip. It should register between 7 and 10.

Success! The cook time will depend on the fats/oils involved. It took 1 hour and 15 minutes for me with this recipe. The soap is no longer caustic and is safe to touch. You can shed all goggles and gloves. Mix in the additives and fragrance (and colorant, if using).

Scoop the mixture into the molds.

Bang the molds down a little to settle. There’s no need to wrap and incubate. You can throw a towel (or paper towel) over it to keep off dust (or cat hair) while it cools.

As soon as it’s cooled and hard–about 12 hours–it’s ready to remove from the molds, cut into bars, and use. If using milk carton molds, just tear the mold off.

These glops that fell off the spoon onto the freezer paper became hard right away.

I made this batch using the ground vanilla beans, white sugar, and fragrance oil–but no cinnamon. See how you can see the flecks of vanilla bean. This thin piece that spilled off the spoon was hard within 5 minutes.

It’s soap! Two hours after starting to make soap in hot process, I have soap. You have to wait 24 hours before you can even think about touching it in cold process. With hot process, I can wash my hands with it right away!

That’s the beauty of hot process–it’s real soap, real fast. An extra plus is that hot process is much closer to how our great-grandmothers made soap. Only we have crock pots! Cold process is too slow for me, and I find hot process to actually be easier.


Clean up! Put all your lye mixing things in a plastic dish pan. Splash in some white vinegar and dish soap. Wash it all up. Scrape out and wipe out your pot and everything else that is soapy then wash them up. Run everything through the dishwasher. Wipe your counters down with a little vinegar and water. Tip: Wash your gloves with your hands still inside them.


Mistakes I made the first time making soap (cold process):

1. I used tap water out of the kitchen sink instead of distilled water. I’m not sure why. I had distilled water and planned to use it. When I went to measure the water, I plum forgot.

2. I had the temperatures off when I combined the lye mixture with the fat/oil mixture. It took so long for the fat/oil mixture to cool down, the lye mixture cooled too much. That’s how I learned to get the fat/oil mixture cooled down to the top of the correct range before starting up with the lye mixing. It doesn’t take long to cool the lye mixture with the cold water bath.

3. I forgot to wrap the soap molds right away, screwing up the soap incubation.

I was trying something for the first time, freaking out about the scary lye, and taking pictures. Probably, that was just one thing too many. But! I still made soap. My first batch of cold process soap, with all these mistakes, took longer to test out safe with the pH strips, but it finally did and it turned out fine. I think it must be hard to mess up making soap. So don’t worry so much!

Note: I’ve also found that mixing in additives one at a time, instead of dumping them all in at once before mixing, helps keep them from trying to clump.


Making soap has been on my personal Dare Debbie list for awhile. Let me know what you think!! I love making soap, and I’m so glad I got over the scary lye. Now you!

P.S. Cindy, who has given me much help and guidance on my soapmaking journey, has some of my “Vanilla Sugar Dreams” soap for sale at her shop, if you’re interested! (Made by her! Not me!) Visit the Chippewa Creek shop here.

P.P.S. Never make substitutions in a soap recipe without recalculating the recipe. For example, if you are a vegetarian and want to make this recipe with shortening instead of lard, you can–but you must recalculate the measurements. The only thing you can change in a soap recipe without recalculating is the additives. To make any other changes, use a soap calculator.

UPDATE: See a more simplified hot process soapmaking post here.

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