Related Clues:

• Caustic potash, e.g.
• Drain unclogger
• 'Fight Club' agent
• Caustic application
• It's used in soap-making
• Potassium hydroxide, e.g.
• Drain cleaner component
• Caustic potash
• NaOH, familiarly
• Wood ash product
• Drain opener
• Candle component
• Caustic alkali
• Caustic matter
• Alkali in cleansers