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Lye Safety Guide

Essential safety information for working with sodium hydroxide (NaOH) and potassium hydroxide (KOH) in soap making.

Important Safety Warning

Lye (sodium hydroxide/NaOH and potassium hydroxide/KOH) is a highly caustic substance that can cause severe chemical burns. Always treat lye with respect and follow proper safety protocols. When in doubt, don't make soap until you've thoroughly researched safe handling procedures.

Required Safety Equipment

Safety Goggles

Splash-proof goggles that seal around your eyes. Regular glasses are NOT sufficient.

Chemical-Resistant Gloves

Nitrile or rubber gloves that cover your wrists. Avoid latex which can degrade.

Long Sleeves & Pants

Cover all exposed skin. Wear closed-toe shoes and consider a lab apron.

Proper Ventilation

Work near an open window or use a fan. Consider a respirator mask for sensitive individuals.

Safe Lye Handling Procedures

1

Always Add Lye to Water

Never add water to lye! This can cause a violent reaction. Remember: “Snow falls on the lake” - lye (snow) goes into water (lake).

2

Use Heat-Safe Containers

Use heat-resistant containers (HDPE #2 plastic, stainless steel, or tempered glass). Lye solution can reach 200°F (93°C) and will melt regular plastic.

3

Add Lye Slowly

Sprinkle lye into water gradually while stirring with a heat-safe utensil. This controls the heat reaction and prevents splashing.

4

Avoid Breathing Fumes

Turn your head away when mixing. The initial fumes can irritate your respiratory system. Fumes dissipate once the lye is fully dissolved.

5

Label Everything

Always label containers with lye solution clearly. Never leave lye solution unattended where it could be mistaken for water.

Do's

  • Keep vinegar nearby (for cleanup, NOT skin)
  • Work on a protected surface (plastic sheet)
  • Keep a dedicated set of soap-making tools
  • Store lye in original container, sealed tight
  • Keep lye away from aluminum (reacts violently)
  • Have running water accessible
  • Work when fully alert and focused
  • Clean up spills immediately with dry paper towels

Don'ts

  • Never add water to lye
  • Don't use aluminum containers or utensils
  • Don't work around children or pets
  • Never leave lye solution unattended
  • Don't rush the process
  • Avoid making soap when distracted
  • Don't pour lye down the drain undiluted
  • Never taste or touch lye with bare skin

Temperature Safety

Warning: Freshly mixed lye solution can reach temperatures of 180-200°F (82-93°C). Allow it to cool to 100-120°F (38-49°C) before combining with oils.

Lye Solution Temperature

Cool to 100-120°F (38-49°C) before mixing with oils. Use an infrared thermometer or candy thermometer to check.

Oil Temperature

Oils should be around the same temperature as lye solution (100-120°F) for best results. Within 10°F of each other is ideal.

Children & Pets

Children

Keep children out of your soap-making area entirely. Lye can cause severe burns and the reaction happens too quickly to prevent injury. Store lye in a locked cabinet.

Pets

Pets can knock over containers or walk through spills. Keep them out of your workspace. Clean up any spills immediately - lye can burn paw pads.

First Aid for Lye Exposure

Skin Contact

  1. Immediately flush with cool running water for at least 20 minutes
  2. Remove any contaminated clothing while flushing
  3. Do NOT use vinegar - it can cause additional chemical burns
  4. Seek medical attention for burns larger than 3 inches

Eye Contact

  1. Immediately flush eyes with cool water for at least 20-30 minutes
  2. Hold eyelids open to ensure thorough flushing
  3. Remove contact lenses if present
  4. Seek immediate medical attention - eye exposure is serious

Inhalation

  1. Move to fresh air immediately
  2. If breathing is difficult, seek medical attention
  3. Rest and avoid exertion
  4. Drink water to soothe throat irritation

Ingestion

  1. Call Poison Control immediately: 1-800-222-1222 (US)
  2. Do NOT induce vomiting
  3. Rinse mouth with water, spit it out
  4. Drink small sips of water or milk if able to swallow
  5. Seek emergency medical care

Emergency Contacts

US Poison Control

1-800-222-1222

Available 24/7

Emergency Services

911

For severe burns or emergencies

A Note About Vinegar

You may have heard to use vinegar for lye burns - this is a myth. Neutralizing lye with an acid creates an exothermic reaction that can cause additional thermal burns on top of the chemical burn. Always use plain water for skin exposure. Vinegar is useful for cleaning lye residue from surfaces and tools, but never on skin.

Now that you know how to stay safe, you're ready to make soap!

Go to Lye Calculator