Thursday, May 21, 2009

Soap Making: 101

I gave a newspaper interview this morning on soap making. It got me thinking that maybe I would post the photos from a couple of years ago when I taught Sidney how to make soap. I was always a little wigged out about having my kids around the caustic chemicals it takes to make soap, but I decided that she was finally responsible enough to pay attention to all of the safety precautions that I would give her without too much eye rolling on her behalf.

Soap making is really just chemistry. Without boring you with all of the formulations, I'll just try to describe what the process is. I use fatty acids (various types of fat that all lend different properties to a bar of soap), water, and sodium hydroxide (a.k.a. lye). See, I really want to go on and on about chemical compounds right here, like the fact that sodium potassium makes liquid soap and how you achieve a clear bar as opposed to opaque, but I'll stop myself...really!) This type of soap making is called "cold processing," although a great amount of heat is actually involved.
The first step in the process is to measure out the various fats into a large stainless steel pot. I had Sid weigh out all of the ingredients on a scale.

Next, she needs to measure out the lye. Lye is an alkali and very caustic. She also will measure out a certain amount of water into a pitcher that will soon be combined with the lye.

Safety gear is a must. Gloves to protect hands from a nasty chemical burn, goggles because you only have one set of eyes, and a mask because once the water is poured into the lye, it becomes very volatile and can burn your lungs. It is choking to breathe these vapors. I won't tell you how I know that. Let's just say, you need to trust me on this!

The water is poured into the lye and stirred until the chunks of lye are dissolved. I forgot to mention that once water and lye combine, the temperature of the mixture shoots up to just under the boiling point. It gets very hot very fast. Notice that I have this sitting on the floor. That is for a couple of reasons. I want the lye water to cool down faster and concrete is nice and cool...and I don't want it to get spilled.

Back to the fat. I have her melt the fat on a stove until it reaches a certain temperature. The temperature varies depending on the recipe that I'm using, but I've done this so much that I can always tell just by looking when it is just right.

After the fat is melted and at the right temp, I pour in the lye water...that has also cooled to a certain temperature. I used to use thermometers for everything, now I rely on timing. (I've done this for about 17 years now.)

After the lye water is added to the melted fat, it begins to change color and will thicken just slightly. Here is where stirring comes into play. Lots and lots of stirring.

So much stirring, that I had the hubby rig me up one of these! It's just a jig that sits atop the pot that I can put a locking drill with a paint stirrer attached to do the work for me. (Otherwise, I'd be here stirring for hours!)

After much stirring, "fillers" can be added to the soap. That means anything that you want to add to make the soap anything other than just "plain soap." Oatmeal, dried lavender flowers, essential oils for a great smell, and color (ultramarine pigments) if you like...lots of different things...but nothing fresh like fruit of vegetables. If it will rot, it will also rot encased in a bar of soap. When the soap reaches "trace," (that is the point, as in this picture, where you can see the trace of a spoon that went through the soap) it is ready to pour into a mold.

I make 12 pound batches of soap and pour them into a butcher paper lined oak box. This soap was a bit past the trace point, but I got so carried away snapping pictures and teaching that it was a bit thick. It happens...not a big deal here as it was still pourable.

Soap in a box!

A lid is put on the box, and then a nice thick layer of foam insulation is put on top. The insulation allows the soap to actually heat up further (chemical process...molecules slamming together...I'll shut up). The soap will go through a "gel phase." This means that it will actually become clear and amber color. It will be very hot. This gel phase allows the soap to be very neutral (chemical-wise) when it comes out of the box. The goal in soap-making, is to have the right amount of molecules all combine and turn into something completely different...soap! That's why, there is not actually lye in a bar of soap. All of those molecules have turned into soap. No lye! (Pun intended.) Some extra fat in a bar of soap is a desired thing, so we soap makers formulate to have a slight excess of fat when finished. This is called "super-fatting" the soap.

A very important part of any task...cleanup! You'd think that you could just add water and get lots of nice suds. Not so! It takes time for the chemical process to happen so all you have right now is caustic soda and fat (thus the gloves). I actually have to use dish soap to clean the equipment!

The next day, I un-mold the soap and cut it into bars. If I wait too long, the soap will get too hard to cut, so I have to do it the next day. It smells wonderful! (This is rosemary patchouli...a favorite.)

Just various kinds of soap that I make. The swirly kind is fun. I will stop now because that's probably already more than you wanted to know. I hope you've enjoyed this little tour of my lab.
-the Farmer's Wife


  1. That is really cool! Here my girls and I just nuke some gylcerin in a cup and pour it in a mold!! lol

    I can so see my husband rigging up something like yours did too. Although sometimes he isn't so sussesful, like the time he tried to invent a mixer for my salt water tank!

  2. Melt and pour is definitely safer. I've also made clear soap. Now that's a dangerous process! It involves heat and 100 proof grain alcohol. Can you say "boom?"