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Lye Safety & Best Practices

Respect the chemistry. Making soap is rewarding, but working with lye requires knowledge, preparation, and unwavering attention to safety.

Understanding Lye

Lye (Sodium Hydroxide for bar soap, Potassium Hydroxide for liquid soap) is a highly corrosive alkali. It is the essential catalyst that turns fats and oils into soap (saponification). Without lye, there is no soap—but it must be handled with extreme care.

Lye can cause severe chemical burns to skin and eyes in seconds. It reacts aggressively with aluminum and zinc, releasing hydrogen gas. It also generates significant heat when mixed with water.

Personal Protective Equipment (PPE)

Never start a batch without your safety gear. This is non-negotiable.

  • Eye Protection: Wear splash-proof safety goggles. Regular glasses are not enough. Lye damage to eyes can be permanent and instant.
  • Gloves: Use chemical-resistant gloves (nitrile or neoprene) that extend up your forearm.
  • Clothing: Wear long sleeves, long pants, and closed-toe shoes to protect your skin from splashes.

Workspace Preparation

  • Ventilation: Mix your lye solution in a well-ventilated area or under a stove hood. The initial fumes can be choking and harmful.
  • Clear the Area: Ensure children, pets, and distractions are out of the room. You need 100% focus.
  • Surface Protection: Cover your workspace with newspaper or a dedicated silicone mat to catch any spills.
  • Equipment: Use only stainless steel (grade 316 or 304) or heavy-duty plastic (PP/HDPE) containers. Never use aluminum, tin, or glass (which can shatter from thermal shock).

The Golden Rule of Mixing

ALWAYS pour Lye into Water.
NEVER pour Water into Lye.

Pouring water onto lye can cause a "volcano" effect—an explosive eruption of caustic steam and liquid. Always add your lye crystals slowly to your water (or other liquid) while stirring.

First Aid & Spills

  • Skin Contact: Immediately rinse with cool running water for at least 15 minutes. Remove contaminated clothing.
  • Eye Contact: Flush with water for at least 15 minutes and seek emergency medical attention immediately.
  • Spills: If you spill raw lye (dry), sweep it up carefully. If you spill lye solution, wipe it up with plenty of paper towels and rinse the area thoroughly with water.

Note: Some makers advocate for vinegar to neutralize spills. While vinegar (an acid) neutralizes lye (a base), applying it to skin can cause an exothermic reaction that creates more heat. Water is generally the recommended first aid for skin contact. Vinegar is fine for cleaning up spills on countertops.

Disclaimer: This guide is for educational purposes only. SudScale assumes no liability for accidents or injuries. You are responsible for your own safety and for researching proper handling procedures for all chemicals used.