Making Soap with Goat Milk: Cold Process

How to make soap with goat milk using the cold process method.

I've been making goat milk soap for almost ten years so it's second nature to me now, but I remember how scary it was the first time I made it.

Once again, let's get the legal stuff out of the way first:

These are the safety procedures I use.
Please note that I am not responsible for accidents;
this post is for educational purposes only.

This post contains affiliate links. Read my full disclosure here.

In an earlier post (How to Measure Oils for Soapmaking) I weighed the oils I'll use in my soap, weighed the frozen milk, and lined my silicon mold (affiliate link) with freezer paper (affiliate link) so it will be easy to get the finished soap out. 

There are two methods of making soap, called "cold process" and "hot process." Both processes begin the same, and that's the part we'll do today - this is how I make cold process soap. Yes, believe it or not, you must make cold process soap before you make hot process soap. (Personally, I like the finished cold process soap better. I'm not sure why hot process soap is so much more popular. Perhaps because it doesn't have to cure as long?)

I assemble my two containers of measured oils. I cover the countertop with several layers of newspaper to protect the surface. I get out my tools: mixing spoons, immersion blender (affiliate link), and plastic mixing bowls. I also get the zipper bag of weighed milk out of the freezer and the lye out of the cupboard.

My rule is to not make soap with children or pets in the room, and to focus only on my soapmaking. I don't have children at home anymore, but I do have dogs and cats in the house. The dogs go in their crates and the cats are "put in time out" in another room. I don't answer my phone if it rings or buzzes or makes any other notification noise.

Be careful when you make soap. Here is the safety equipment you'll need: goggles, gloves and mask.

I don an apron and my goggles, rubber gloves and mask (affiliate links). Hubby says I look like a mad scientist.

Weigh the lye

Next I weigh the amount of lye I'll need. I weigh it in an old margarine tub that is well-labeled, and set it next to the sink with the lid on.

Warm the oils

I weighed the liquid oils into one container and the solids such as tallow, lard and coconut oil into another. Do you remember I said in my previous post that lye burns the milk sugar and turns the soap brown? This is why I use frozen milk and why I keep the two kinds of oil separate: to keep things as cool as possible: to keep the browning to a minimum.

How to make soap with goat milk using the cold process method.

I warm up the solid oils and butters in a saucepan until they melt and liquify, then pour them in the larger of my mixing bowls. I add the room temperature liquid oils (olive oil, etc) to the melted oils. The room temperature oils help to cool the heated oils a bit. I pour this whole mixture into the dishpan in my sink. Having the dishpan set inside the sink puts it at a comfortable level for me to work, and it also keeps everything stable and less likely to topple or slip or suffer some other calamity.

Add the lye to the milk

The frozen milk goes into my smaller mixing bowl and I sprinkle the lye on top, then put the lid back on the tub the lye was in and set it aside. I don't leave an open container of lye sitting around, even if the container is empty.

How to make soap with goat milk using the cold process method.

Remember, you must always add lye TO the liquid. Adding liquid to lye will cause an eruption of caustic lye that can be very dangerous.

How to make soap with goat milk using the cold process method.

Using my mixing spoon I carefully stir the lye and frozen chunks of milk. The heat of the lye will melt the milk. Keep stirring until all of the frozen milk has melted. I love these old Rubbermaid bowls with pour spouts because I can hold onto the handle while stirring; I found them at a thrift store. If you aren't lucky enough to find some at a thrift store, these batter bowls from Amazon are very similar (affiliate link).

Add the lye/milk to the oil

I slowly add the lye/milk mixture into the oils, stirring as I go. (Again, add the lye mixture TO the oils.) Stir gently so the lye mixture doesn't splash around.

How to make soap with goat milk using the cold process method.

If I were making a water-based soap, the directions would say to let the lye/water and the oils cool to the same temperature before combining. Because I'm using milk, I skip that step and add the lye/milk to the oils regardless of their differing temperatures.


... and stir and stir and stir. Using an immersion blender helps this step go a bit faster.

How to make soap with goat milk using the cold process method.

I alternate between using the stick blender and stirring with my mixing spoon. I don't want to burn out the motor on the blender. I'm careful to keep the blender submerged when it's turned on so the raw soap doesn't splash or spurt.

How to make soap with goat milk using the cold process method.

Bring the mixture to "trace"

The goal is to bring the mixture to "trace". Eventually you'll notice that the color has changed, instead of being transparent it changed to translucent and then became opaque. It will begin to thicken after awhile. "Trace" is kind of hard to explain. Let's see, it's thick enough that when you pick up the spoon, the liquid soap that falls off doesn't immediately disappear into the rest, it sort of sits on top of the surface. Or you can drag the spoon through the soap and a line will remain visible.

How long does it take for the soap to reach trace? It's different every time, and it depends on the room temperature as well as the temperature of the ingredients and even on the type of oils you are using. Just keep stirring and blending until it's thick.

How thick? I tend to take mine to a thick or medium trace. Some soapmakers like a light trace that is much thinner than mine. There's a bit of leeway here. It's easier to tell a heavy trace from a light trace.

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This is where cold process and hot process part ways.

I prefer cold process soap. It looks smoother when it's finished and the color is lighter. Hot processed raw soap is much thicker; the difference is like cake batter (cold process) and a stiff mashed potato consistency (hot process). I think the cold process method is much easier too, but hot process is quite popular, probably because the curing time isn't as long.

This batch is cold process, so at this point I simply pour the soap into my mold, use my mixing spoon to scrape out the dishpan, cover the mold with a piece of paper to keep dust out, and walk away. I leave it undisturbed for 24-48 hours, then unmold it and let it set for another 24 hours or so before cutting. I do this in the mudroom, where I can close the door and not worry about the cats getting into the raw soap on my workbench or dog hair landing in it.

Clean up

Because I don't have small children anymore, I just put all my soap-covered utensils and bowls and tools (my immersion blender comes apart so I can put the electrical part away) into the dishpan while still wearing my protective goggles and gloves, stick the whole thing in a garbage bag, twist it closed and clip it with a clothespin or binder clip. I set it on the highest shelf in the mudroom, and leave it until the next day. By then, the soap has completely saponified and it isn't caustic anymore - it's soap instead of caustic lye and oils and milk.

Then I put it all in the kitchen sink, fill the dishpan with water and let it all soak for a bit, then I wash everything. I don't have to wear rubber gloves at this point. No need to add dish soap, because the newly-made soap I'm washing off of my utensils will do the job just fine.

If you have children at home, you'd probably want to clean it all up instead of leaving it on a shelf unwashed. I'll let you research the best way to do that since I haven't done it myself. Be sure you're still wearing your rubber gloves when you clean up.

How to make soap with goat milk using the cold process method.

We'll unmold, cut and cure the soap in another post, but here's a sneak peek at my finished cold process bars.

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In this series:
Basic Equipment You'll Need to Start Making Soap
How to Measure Soap Oils and Safety Procedures
Soapmaking: Cold Process
Soapmaking: Hot Process
Soapmaking: Unmolding, Cutting and Curing

If you've ever used goat milk soap, you know how luxurious it is. Here's how to make your own using the cold process method.

This post has been shared at some of my favorite blog hops.


My hope is to inspire you, and to encourage your homesteading plans and your dreams of a simple, self-reliant, God-dependent life. You can follow me at: 
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