Make your own soap! Cold process soap making

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Make your own cold process soap!

Soap making has come a long way since your grandmother’s day.  Ingredients that would have been exotic and unheard of in her day, you can pick up at your local grocery store.  I am always looking for an outlet for creativity and I love trying out new projects – plus in the end you get something useful that your family will use everyday.  Homemade soap also makes a great gift!

The process isn’t hard, but until you get the hang of the way things work it’s definitely a good idea to follow instructions EXACTLY.  Once you feel more comfortable you can start experimenting with different oils, additives, colors & fragrances.  The possibilities are endless!  There are several techniques of soap making out there.  The one we will discuss here is cold process soap making.  I like cold process soap making the best because I feel like it gives you the most options for adding fun ingredients, doing swirls and it makes a nice smooth bar.

All about Lye

Most of the ingredients in soap making are perfectly safe & food grade, but there is one big exception.  When making soap you need to use sodium hydroxide, commonly known as lye.  Lye has many uses including as a commercial cleaning agent, drain cleaner, and it is used for chemically peeling fruits & vegetables.  In cold process soap it causes a chemical reaction called saponification.  Think back to your days in school.  In science class we learned that when you mix an acid (fats & oils) & a base (lye) it will cause a chemical reaction.   You have to measure accurately to get the proper reaction.  Our goal is to add just enough lye to cause saponification, but not too much that lye is leftover in your finished soap.  Properly done, each sodium hydroxide molecule will combine with an oil molecule, transforming it so it is no longer oil or lye, but a new molecule – soap.  Most soap recipes will have you add more oil molecules than needed, a process called superfatting, which will leave the leftover oil molecules to clean & moisture your skin.

I know, I know, it can be confusing and luckily it’s not really necessary to know to make soap – basically lye turns fats & oils into soap with the magic of science!  The only thing you need to take away is this is SCIENCE not cooking.  You need to measure very carefully, and you need to take appropriate safety precautions.  Lye is extremely caustic.  It will react with the oils on your skin and leave you with very nasty burns.  If you inhale it, it will chemically burn your lungs. If some splashes in your eyes, it will burn your retina.  If some lye or soap batter should get on your skin, immediately flush the area for several minutes with cool water. This stuff is no joke.  Wait until your kids are in bed and your pets have settled down so no one is running around while you are working.  Tie up your hair, wear long gloves, a face mask & safety goggles.  Do not use your soap making bowls, utensils, etc for food (once you use them for soap, they should be marked & stored away from your normal food prep supplies).  Get a special container with a secure lid to store your lye.  Mine is in a gallon ziplock bag inside a stainless steel latched container. I keep it on top of my soap cabinet, well out of reach of tiny hands & paws.  I know someone who keeps her lye in a gun safe to keep it away from her little ones!  Lye can be tricky to find in stores, it really is just easiest to order it online.  I buy mine here

Make your own soap! Cold process soap making

Equipment you need to get started

You will need to gather up some equipment before you can get started.  Try searching thrift stores or yard sales to see if you can find some of this second hand to keep costs down.  As I mentioned before, none of your soap making supplies should ever be used for food prep to avoid contamination.  Mark them and keep them outside of your kitchen so other family members won’t use them by mistake. At the end of this post, you will find some handy shopping links!

*several heat resistant bowls
*spoons & rubber spatula
*immersion blender 
*digital kitchen scale
*digital thermometer
*long rubber gloves
*face mask (preferably one rated for chemicals)
*safety goggles

*something to cut your soap
*soap mold (you can purchase soap molds, or use a silicone baking mold)

Make your own soap! Cold process soap making

Make your own soap! Cold process soap making


Ingredients for making soap

Really the sky is the limit here!  You can go fancy and use oils like Meadowfoam, Apricot Kernel Oil, Mango Butter or Cocoa Butter.  You can also use basic oils you’d find at the grocery store like olive oil, canola oil or sunflower oil.  An excellent  website for soap makers is , they have every kind of oil, butter & fragrance you could want.  They also have a blog with amazing soap recipes to try (using their products of course!).

You will want to familiarize yourself with a Soap Calculator.  I like the one here.  It’s a great way to see the properties different kinds of oils will add to your soap.  It will also give the exact amount of lye, oils, and fragrance to add.  I run every single recipe I try through here, even if I am using a recipe I found on a reputable website or book, just to double check the work.  Anyone can make a typo, and you don’t want to end up with lye heavy soap.  The soap calculator is also handy for when you want to substitute an oil in a published recipe for one you have on hand.  Different oils require different amounts of lye to saponify.  A new oil could cause the lye measurement to be different so it is important to run any changes through the calculator.

Make your own soap! Cold process soap making

Basic Soap Recipe:

34% Olive Oil
33% Coconut Oil
33% Palm Oil

These three oils are some of the most commonly used in soap making.  Olive Oil is very moisturizing, Coconut Oil is cleansing, and Palm Oil is great for lather.  After your first batch, you can try adding  more oils  (sometimes 7 or 8 oils!) each one adding something special to the mix.  But let’s start small and simple.

The recipe we are working with requires 25 oz of oils.  This will fill my 10 inch silicone mold about 3/4 of the way.  In the soap calculator, change the weight of oils to 25 ounces.  All the other settings will default to standard amounts.  Again, with experience, you can play around with changing them but for now, let’s just leave them there.  Select the three oils and add the percentages.  Hit “calculate recipe”, then “view/print” and you are ready to go!  For this recipe, we will need:

8.5 oz Olive Oil
8.25 oz Coconut Oil
8.25 oz Palm Kernel Oil
9.5 oz water (use room temperature distilled water)
3.91 oz lye

fragrance or essential oils for scent (optional)
clay, micas, infusions, oxide powder or other colorant (optional)


Let’s Get Started!

First, clean the kitchen!  You will need plenty of clear counter space, and an empty sink (no dirty dishes!)

Measure out your distilled water.  Put on your gloves, goggles & mask.  Measure your lye.  Slowly pour the lye into the water (never pour the water into the lye as it can splash up).

Make your own soap! Cold process soap making

Stir the lye water until lye is completely dissolved.  DO NOT LEAN OVER BOWL.  Try to keep your face as far back as possible and keep your mask on because as the lye dissolves it will give off fumes that you do not want to inhale.  The mixture will start off foggy, but will be clear when totally dissolved.

Make your own soap! Cold process soap making

Once the lye mixes with the water, it will heat up very rapidly.  Depending on how much water/size of bowl it can easily reach over 200 degrees within seconds.  Set aside your lye mixture and allow to cool.  I like to set my bowl of cooling lye in the sink.  It is possible for lye water to heat up so much that it actually can burn through the plastic bowl.  Lye should never be mixed in a glass bowl as the lye can etch the glass, over time eroding it.  One day you will end up with a shattered glass bowl and lye water split everywhere!  Allowing the lye water to cool in the sink ensures that if for some reason your container fails, you don’t have a chemical spill in your kitchen.

Make your own soap! Cold process soap making

While the lye water is cooling we will work on the oils.  Measure each of the oils and add to a large bowl.  I take my gloves, goggles & mask off for this part, they are bulky to wear and the oils aren’t going to hurt you.

Make your own soap! Cold process soap making

Put the bowl in the microwave for 30 seconds.  Stir well.  Put in for another 30 seconds.  Alternately, you could put the oils into a double boiler on the stovetop to melt.  Continue this until oils are completely melted together.  They should be nice and clear

Make your own soap! Cold process soap making

Now we need to wait for the oils to also cool.  The goal is to get both the lye water and the oils to be between 110-120 degrees.  It is not the end of the world if they cool off too much.  In fact plenty of soapers prefer to use room temperature oils & lye water.  The more important thing is to try and keep the temperature of the oil and temperature of lye water within 10 degrees of each other.

While we are waiting for everything to cool, it is time to measure out any additives to your soap.  You can add essential oils, fragrance oils, minerals for color, clays, purees….there are so many options!  I am going to add some avocado puree and some dispersed sea clay (1/2 tsp sea clay mixed with 1 tsp olive oil).  Dispersing the clay into a little olive oil helps it to blend into the soap instead of sitting there in chunks. I am also adding some lavender & rosemary essential oils for fragrance.  Don’t add them yet, just get everything ready & measured out.  The amount of fragrance or essential oils you will add depend on the safe usage amount for that product.  Fragrance oils should have the usage marked on the bottle or can be found on the manufacturer’s website.  Essential oils can be a little trickier, but this is a good guide that I use  – click here for essential oils guide

Once your oils & lye water are the proper temperature, it’s time to put your gloves, goggles & mask back on.  Carefully & slowly, pour your lye water into your oils.  Try to avoid splashing.  Tap your stick blender against the bottom of the bowl a couple times to release any air bubbles, then thoroughly blend, being careful as you move your stick blender around that you do not splash any of the mixture around.

Make your own soap! Cold process soap making

After you have blended for a few minutes, you will notice the mixture begins to thicken.   This is known as trace.  If you lift the blender out, the mixture that dribbles off should leave a light trace before sinking in.  It will be the consistency of slightly liquidity pudding.

Make your own soap! Cold process soap making

Now is the time to add your fragrance or any additives.  Add it in and quickly blend or hand stir.  The chemical reaction is going to start to accelerate and it can begin to harden quickly.  Some fragrances and additives can make it go even quicker, so don’t over blend.

Carefully pour the mixture into your soap mold

Make your own soap! Cold process soap making

Tap the mold against your counter a few times to loosen any air bubbles that might be trapped.

Cover your mold and wrap it snugly in a towel.  You want to keep the warmth inside to help your soap reach the gel phase where the saponification process speeds up and helps make a nice hard bar.  If you don’t insulate, your soap may not reach gel phase, or not reach it long enough.  It can leave discolorations that are not harmful, but don’t look very nice.  There are some exceptions to the insulating rule, particularly with recipes that contain food ingredients like honey or sugars.  They should not be insulated and can even be left in the refrigerator.  The natural sugars in the these recipes could cause the batter to overheat to the point where it could volcano out of the mold!  But for this recipe today, we will insulate.

Make your own soap! Cold process soap making

Clean up

Now it’s time to clean up your soap making tools.  Keep your gloves & goggles on for this so the soap batter doesn’t get splashed on you.  If you have any unused batter, scrap as much as you can into the trash so it doesn’t turn to soap in your drains.  Put all the bowls, spoons and tools in the sink.  Using hot water and a little dish soap wash everything. I use paper towels so I can just toss them at the end, but you could also use an old dishrag set aside for soap cleanup.  When you are done, let the hot water run in your sink for a bit to flush the batter from your pipes.  Finally, wipe all your work surfaces (counters, sink) with diluted white vinegar.  Lye is an extreme base and vinegar is an extreme acid so it can work to neutralize the lye on hard surfaces.  DO NOT put vinegar on your skin if you have splashed lye on it, it will make the burn worse!

And now we wait….

I know it’s tempting, but let your soap sit for at least 24 hours wrapped up.  When you check on it, you disrupt the temperature.  I peeked at mine so you can see it – this is after about 12 hours

Make your own soap! Cold process soap making

You can see the soap mixture is nice and dark and has a clear glycerin look – this is the gel phase.  You can see the tiny air bubbles that came to the surface when I tapped the mold on the counter.  They will go away by the end of the process.

After 24 hours you are ready to unmold!  See that discoloration on the left side – and a bit along the top.  This is why we don’t peek at sleeping soap!  Loosen your mold along all four sides (being careful not to nick it with your nail like I did!).  The soap will still be slightly soft.

Make your own soap! Cold process soap making

Flip the mold upside down and gently run your hand along the bottom to completely loosen the soap from the mold.  If the soap is not easily releasing from your mold, it is not ready to come out yet.  If you force it out, it could just crumble and break.  Let it sit a few more hours.

Make your own soap! Cold process soap making

Now you just have to cut it into bars.  You want to try and keep them evenly sized.  On the back side of my soap mold lid, I drew a handy little cutting guide.  You could also use a miter box or slab cheese cutter for super straight edges & even bars.

Make your own soap! Cold process soap making

This time, I used a metal dough scraper to cut my soap brick.

Make your own soap! Cold process soap making

The soap is not dangerous to handle with your bare hands.  After the 24 hours is up, saponification is complete and there should be no lingering lye left in your soap.  BUT it is not ready to be used yet.  If you used it now, it will pretty much dissolve into a gooey mess.  The soap needs to cure for 4-6 weeks.  During that time, the excess water will evaporate out of the bar, leaving you will a nice, hard, final bar of soap.  Let it stand on one of the narrow edges.  The more of the bar that is exposed to the air, the faster it will cure.  Mark the date somewhere so you will remember when it’s ready to go.

That’s it!  I know it sounds like a lot, but once you make a batch or two you will totally have the hang of it and you will be ready to try more complicated recipes, or even come up with some amazing ones of your own!

Want to check out some of my shared recipes?

Coffee Lover’s Handmade Soap

Cocoa Mint Handmade Soap

Make your own soap! Cold process soap making


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Tuesdays with a Twist

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