What is a Soap made of?
What is a Soap made of?
Fats reacted with lye to make fatty acid salts — and most modern "beauty bars" are not soap at all.
Saponification is one of the oldest chemical processes people run deliberately, and the reaction is irreversible — there is no free lye left in a properly made bar. The label is the giveaway for what you are holding: a product legally called soap lists sodium tallowate or similar, while a "beauty bar", "cleansing bar" or "facial bar" lists a synthetic surfactant and is not soap, because plain soap at pH 10 disrupts the skin barrier. Antibacterial soap is a separate question again: the US FDA banned triclosan and eighteen other antiseptics from consumer wash products in 2016 on the grounds that no benefit over plain soap had been shown.
Component by component
| Part | Material | Why that material |
|---|---|---|
| the soap itself | sodium salts of fatty acids: sodium tallowate, sodium palmate, sodium cocoate | Each molecule has a water-loving end and an oil-loving end, so it lifts grease into water — the entire mechanism. |
| alkali | sodium hydroxide for bars, potassium hydroxide for liquid soaps | Potassium soaps are softer and stay liquid, which is the only real difference between bar and traditional liquid soap. |
| glycerin | a by-product of saponification, often removed and sold separately | Glycerin draws moisture to the skin; commercial bars often strip it out, which is why handmade soap feels less drying. |
| syndet bars | synthetic detergents such as sodium cocoyl isethionate | Real soap needs a pH around 9-10 to exist; a syndet bar can be made at skin pH, which is far gentler. |
| additives | fragrance, titanium dioxide for opacity, chelators such as EDTA | The chelator stops calcium in hard water reacting with the soap into scum, which is what leaves a ring in the bath. |
Other around the house objects
- Banknote Cotton and linen rag paper, or polymer film — never wood pulp, which is why notes survive the wash.
- Lego brick ABS plastic moulded to a tolerance of about ten micrometres — the tightness of the fit is the whole product.
- Toothpaste Mostly abrasive and humectant, with a detergent for foam — the active ingredient is about 0.15% fluoride.
- Coin Base-metal alloys chosen for wear and cost — most modern "silver" coins are copper-nickel and most "copper" ones are plated steel or zinc.
- Sunscreen UV filters — mineral, chemical or both — suspended in an emulsion whose job is to hold them in an even film.
- Credit card Laminated PVC sheets 0.76 mm thick, carrying a silicon chip in epoxy and a copper antenna coil.
- Candle Wax that is really a fuel, and a braided cotton wick that acts as a pump rather than as the thing burning.
- Lipstick Castor oil carrying pigment, set into a stick with waxes — the oil is the workhorse, not the colour.
- Shampoo Three-quarters water, a primary detergent, a milder secondary one, salt to thicken, and silicone to make hair feel smooth.
- Balloon Party balloons are dipped natural rubber latex; foil balloons are metallised plastic film and are not rubber at all.
- Deodorant Deodorant kills the bacteria that cause the smell; antiperspirant uses aluminium salts to plug the sweat duct. Different products.
- Toothbrush Nylon filaments stapled into a polypropylene handle with a wire — three plastics that cannot be separated for recycling.
Common questions
- What is a Soap made of?
- Fats reacted with lye to make fatty acid salts — and most modern "beauty bars" are not soap at all.
- What is the the soap itself of a Soap made of?
- Sodium salts of fatty acids: sodium tallowate, sodium palmate, sodium cocoate. Each molecule has a water-loving end and an oil-loving end, so it lifts grease into water — the entire mechanism.
- What is the alkali of a Soap made of?
- Sodium hydroxide for bars, potassium hydroxide for liquid soaps. Potassium soaps are softer and stay liquid, which is the only real difference between bar and traditional liquid soap.
Related pages
- Banknote Cotton and linen rag paper, or polymer film — never wood pulp, which is why notes survive the wash.
- Lego brick ABS plastic moulded to a tolerance of about ten micrometres — the tightness of the fit is the whole product.
- Toothpaste Mostly abrasive and humectant, with a detergent for foam — the active ingredient is about 0.15% fluoride.
- Coin Base-metal alloys chosen for wear and cost — most modern "silver" coins are copper-nickel and most "copper" ones are plated steel or zinc.
- Sunscreen UV filters — mineral, chemical or both — suspended in an emulsion whose job is to hold them in an even film.
- Credit card Laminated PVC sheets 0.76 mm thick, carrying a silicon chip in epoxy and a copper antenna coil.
- Candle Wax that is really a fuel, and a braided cotton wick that acts as a pump rather than as the thing burning.
- Lipstick Castor oil carrying pigment, set into a stick with waxes — the oil is the workhorse, not the colour.
- Pencil Stationery and paper
- Tennis ball Sport and games
- Golf ball Sport and games
- Paper Stationery and paper
- Glass Building materials
- Soccer ball Sport and games
Sources
- Official vendor product documentation — At One Place