Potassium Hydroxide vs Sodium Hydroxide Key Differences Explained
Potassium hydroxide (KOH) and sodium hydroxide (NaOH) are strong bases—white solids that dissolve in water to make caustic, slippery solutions. Each releases hydroxide ions that rip apart fats and proteins, making both handy for heavy-duty cleaning.
People confuse them because labels say “lye” or “caustic soda” interchangeably, and both sit near each other on store shelves. Picking the wrong one can leave you with a soap that’s too soft or a drain cleaner that etches metal.
Key Differences
KOH dissolves faster and feels more aggressive on skin, while NaOH is cheaper and forms harder soaps. KOH is favored for liquid soap; NaOH for bar soap and most drain openers. Swap them and recipes flop.
Which One Should You Choose?
Need liquid soap or a gentler drain product? Grab KOH. Making bar soap or scrubbing tough clogs? Stick with NaOH. When in doubt, follow the recipe—it was written for one, not both.
Can I swap them in any recipe?
No. Each needs different amounts and gives different textures. Stick to what the recipe lists.
Are they safe for home use?
Both can burn skin and eyes. Wear gloves, goggles, and work in a ventilated space.