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soapworks the nutritional scientist's view by Dr. Jane

Soapmaking probably began in ancient Rome, where fat and ash accumulated at the base of the sacrificial altars. This early 'soap' formed naturally from the fat and ash and washed down the hillside to the working washerwomen. The women were thrilled to find that the 'sapoclay' was great for laundering dirty togas.

Today we use a combination of fats and oils from vegetable and animal sources. Rather than ash, we use sodium hydroxide (aka 'lye'). And we spice up our soap mixture with appetizing fragrances and colorants. Sometimes we add special ingredients such as oatmeal, goats milk, herbs, and honey.

The pictures below summarize how we make soap. You will notice that we can keep our togas clean without sacrificing any animals, much to the relief of our goats.

First things first: the raw ingredients

Nothing too special here. Looks like the fats that you purchase from any grocery store. Soy and olive oils are staples. These jugs are big. We will use more than half a gallon of olive oil to make 24 bars of castile soap. The color of the soap comes from the color of the ingredients: yellow oil = yellow soap.

Fats, Fats, more Fats

Here is a 50 pound bucket of coconut oil. This fat is a staple to soapers because it makes lots of great big bubbles. People like soap that lathers up nicely.

The sophisticated oils and fats

There are all kinds of specialty oils that we usually add to our soap, lotion and creams. For example: sweet almond oil, apricot kernel oil, shea butter, wheatgerm oil, castor oil, cocoa butter, beeswax, and jojoba oil. These oils may be from Africa, the South Pacific or other exotic locales.


No lie: LYE!

The essential ingredient to all soap processing is sodium hydroxide, or lye. We buy granular lye in a 50 pound bag from a laboratory supply house. This is quite a bit of lye. Because it does not store well over time, we share it with our soaper friends. Lye is a very corrosive material, capable of burning skin, clothes, and eyes. Soapmaking is not for the sloppy or the fearful.

We use distilled water or goats milk to solubolize the sodium hydroxide.


The yum yum ingredients: scent, color and texture

There are literally thousands of scents available for soapmakers. *Fragrance oils* are manufactured in the laboratory from scratch. *Essential oils* are produced by steam distillation of botanical materials. We use both fragrance and essential oils in our soaps, sometimes in combination, sometimes straight up.

If we want color, we can add finely powdered inert oxides or naturally color-producing herbs and spices (e.g. parsley, paprika, and tumeric). For exfoliating texture we use oatmeal, corn meal, pumice. You get the idea.

We are very fond of soaps with* no added scent* and *no added color*. So are many of our customers.

 

Recipe for success

Just like you would follow a recipe in the kitchen when preparing a dish, we also follow a soap recipe. Most soaps use 3-10 different types of fats or oils plus other ingredients.

All ingredients are weighed out to the gram (this is a lot of fun for the closet chemists).

Using formulas that account for the quantity and type of fat, we calculate the exact amount of sodium hydroxide that should be added to saponify the fats. More about saponification later on.

One great little weighing scale

We just purchased this top-loading digital scale that converts ounces to grams and kg. Very very handy and accurate.

Getting ready

Before we actually start combining ingredients, we set out all the materials. Notice the tiny bottle of fragrance oil, the handheld blender, the scale and the lined soap molds. The towels protect the surface of our kitchen counter. The yellow egg yolks are an essential ingredient in a 'historical soap' that we are trying for the first time. This should work.

Starting to heat up!

We melt the solid fats on the stove in an ordinary sauce pan .

The cold water bath

There are 2 buckets in this picture. On the left is our sodium hydroxide solution and on the right is the melted fats. The ingredients in both buckets must be carefully handled and only combined when their temperatures are about 100 degrees F. We use thermometers and a cold water bath set up in the sink (kitchen chemistry at its best).

To trace or not to trace

When both the lye and the fats are at the same temperature, we combine and homogenize them in a plastic bucket using our stick blender. In about 1-10 minutes the mix will begin to thicken. Soapers call this stage *trace*because the dribbled mix will leave a surface trail.

It is at the trace stage when we add the scent oils, the goats milk, oatmeal, colorant, and most of the other yum yum ingredients.

Now pour carefully

The mix is poured into the molds. At this stage the mix is about the consistency of eggnog. In fact, all of the color you see in this old fashioned egg yolk soap is from egg yolks. You may be tempted to taste a spoonful of the mix because it looks and smells yummy, but it is still very corrosive. Resist the temptation.

Put the soap to bed

The poured molds are covered with cardboard (high tech) and then with several towels and blankets for insulation. During the next 8-12 hours or so, most of the saponification occurs. Saponification is an exothermic reaction, meaning it gives off heat forcing the soap to form a 'gel' before it cools.

In front of the two molds that we just filled with the egg yolk soap is a previous batch hidden under insulating towels.

Christmas morning at last

The next morning, while still in our pajamas, we cut the soap. This is exactly like cutting fudge only the pieces are bigger. It is still not a good idea to lick your fingers.

Oh, what beautiful bars

The bars are lined up in high tech cardboard boxes to begin the curing process. In a week or so the bars will have their edges beveled. Trimmings are recycled.

The waiting game

The soap is dried for 4 weeks. This is the hardest part. We want to use the soap immediately. But if we did that, the soap would soon be a sticky puddle at the bottom of the shower. No fun. It takes 4 weeks to assure a solid soap that when used will last a very long time. After counting down the 28 days, we label and wrap the soap. Now the soap is for sale.

Saponification up close and personal

This section is for those who got a C or better in any chemistry class.

Saponification is a process by which triglycerides react with sodium hydroxide (or potassium hydroxide) to produce glycerol and a fatty acid salt, called 'soap'.

All fats are composed of triglycerides which are 3 fatty acids attached to a 3 carbon glycerol backbone (by ester bonds). A triglyceride is on the top left of the figure. When the fat is exposed to sodium hydoxide, the ester bonds are broken, the fatty acids then combine with the sodium in a process known as 'saponification'. The products of the reaction are glycerol and the Na-fatty acid molecule (labeled 'crude soap').

The Na-fatty acid molecule is an amphophilic molecule . . . which means that one end of the molecule wants to be water (hydrophilic). And the other end that wants to be in fat (hydrophobic). It is because one molecule is happy in both a fat and an aqueous environment that allows the soap to 'dissolve' away the grit and grime on your hands.

Note that the 3 carbon glycerol molecule stays in handmade soaps. This is good because glycerol is a moisturizer and one of the main reasons that we love handmade soaps. Most commercial processing removes the glycerol.

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