The Science of Suds

A Visual Guide to the Art & Chemistry of True Soapmaking

The Chemistry Lab

True soap is the result of Saponification: a chemical reaction between triglycerides (fats) and an alkali (lye). Most store-bought "soaps" are actually synthetic detergents (Syndets).

Soap vs. Detergent: The pH Scale

One of the easiest ways to identify true soap is its pH. True soap is naturally alkaline (9-10), making it hostile to bacteria but requiring cure time to be mild on skin.

True Soap

  • Ingredients: Saponified oils (Sodium Olivate, Sodium Cocoate).
  • Mechanism: Traps dirt in micelles; naturally creates glycerin.
  • Feel: "Squeaky" clean; biodegradable.

Syndet (Synthetic Detergent)

  • Ingredients: Sodium Lauryl Sulfate (SLS), SCI.
  • Mechanism: Petroleum or plant-derived surfactants stripping oil.
  • Feel: Often leaves a film; pH balanced (5.5-7).

Ingredient Profiler

No single oil makes a perfect bar of soap. Soapmakers blend oils to balance five key properties. Click the buttons below to see how each oil contributes to the final bar.

Coconut Oil Profile

The powerhouse of lather. It creates huge, fluffy bubbles and a very hard bar, but can be stripping to the skin if used in high percentages (over 30%).

Respect the Lye

Sodium Hydroxide (NaOH) is mandatory for making soap. It is also a caustic chemical that causes severe burns. Safety is non-negotiable.

ALWAYS ADD LYE TO WATER
(Never add water to lye!)

Eyes & Skin

Must wear chemical splash goggles and long sleeves. Lye blindness is permanent.

Ventilation

Mixing lye releases choking fumes. Do it outside or under a stove hood.

Tools

Use stainless steel or #5 plastic. NEVER use aluminum (it explodes hydrogen gas).

First Aid

Flush burns with WATER for 15 mins. Do not use vinegar on skin (it creates heat).

The Cold Process Method

The gold standard for artisan soap. It relies on internal heat generation.

1. Preparation

Weigh oils and lye separately using a digital scale. Precision is key—no cups or spoons!

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2. Lye Solution

Slowly pour lye into water. Stir well. The mixture will superheat to 200°F+. Set aside to cool.

3. Emulsification

Pour lye water into oils. Stick blend until "Trace" (pudding consistency). Add fragrance now.

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4. Pour & Harden

Pour into mold. Cover to insulate. Saponification happens over the next 24 hours.

5. The Cure

Unmold and cut. Let bars sit on a rack for 4-6 weeks to evaporate water and harden crystalline structure.

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Troubleshooting

Soda Ash

White powder on top

Harmless reaction with air.
Fix: Steam it off or wash. Prevent with alcohol spray.

Seizing

Soap-on-a-stick

Caused by floral fragrances or high heat.
Fix: Hot process it or smash into mold immediately.

Lye Pockets

Weeping liquid holes

Incomplete mix or heavy lye.
Fix: UNSAFE. Rebatch carefully or discard. Do not use.