Soap is ubiquitous in our lives, and for good reason. We need something to keep us clean! But how exactly does soap work? And what is it? 

Why is that important? Well, it means that we can begin our historical exploration of soap millennia ago instead of considering it a modern invention. Indeed, evidence of soap production can found as far back as 2800 BC in ancient Babylon. 

Soap becomes something more popular in Roman times, popping up in Latin writing from the first through fourth centuries BC. Because it is so necessary to human life (cleanliness is not next to godliness, it is concomitant with survival!), we find soaps being made around the world in similar time frames. The Middle East became a mass-producer of soaps, particularly the Aleppo soap, which would lead us to modern Castile Soap (these soaps are unique for their high percentage of olive oils, which were readily available in the Middle East). It seems that after the Crusades, European soldiers returned to England with bars of soap and spurred the soap-making industry in London and France. From there we move seamlessly into modern times, where soap is made from high quality oils and fats and infused with exfoliants, scents, vitamins, and minerals.

As I mentioned earlier, cleanliness is important to survival. As a species, the more diseases we can wash away from our skin and food, the less likely we are to perish from illness. So how does soap help us in that pursuit? Soap molecules are bipolar. Imagine a small sphere. The outside is hydrophilic (which means it attracts and locks onto water), and the inside is lipophilic (which means it attracts and locks onto fat). Fats, which are not normally water soluble (think of those greasy stains on your pots and pans, they don’t simply disappear with a water rinse) are attracted to the lipophilic center of these soap molecules and then trapped in the hydrophilic exterior. That water-loving exterior can now be washed away, it has made the fat soluble in water.

Let’s get to the making of soap! This is a simple process, but I must emphasize the necessary safety precautions. You are about to conduct a chemistry experiment with caustic (i.e. dangerous) compounds. Rest assured, this process has been used for centuries and if you follow a few rules you should be fine.

1. Wear protective gear: gloves, an apron, long sleeves, and goggles
2. Work in a well-ventilated space (i.e. outside)
3. Keep a spray bottle of vinegar on hand (if you spill lye on your skin you'll want a strong acid like vinegar to counteract the chemical burn)

Ingredients

• 80 grams Lye
• 195 grams Water
• 600 grams Olive Oil
• Optional: Essential Oils, Scents (7-12 grams)

Mix lye into the water, not the other way around. This new compound will heat up, that is a sign of reaction (a good thing). Make sure you are using a heat receptive content (i.e. something that will not melt). Let this cool for a bit, keep it away from tongue-wagging dogs and curious children.

Pour the lye mixture into a bowl with your fat mixture. We will now emulsify, which means suspending molecules of water in a fat solution. The soup will thicken, beginning to look like thin pudding. This phase is referred to as trace by soap makers. It is now appropriate to add exfoliants (oatmeal, chia), and scents (mint, lavender). 

Pour the soap into containers (you can find pretty moulds or simply use plastic containers sprayed with a bit of oil). Let this set for 24 hours. You will see that the soap changes during this period, what is happening? This is what we call saponification. The fatty acids and sodium hydroxide are consuming each other to produce soap. Though lye is caustic, there will be absolutely none left in the finished product; it is completely eaten up and removed!

Unmold your soaps and cut them up. They will continue to saponify for the next two weeks, drying and becoming more presentable. The soap is fully cured after a few weeks. You'll know it's ready when it is no longer soft. Pack a few away for gifts and then get scrubbing with the rest!