Section 06 Products of the chemical or allied industries 28 Inorganic chemicals; organic or inorganic compounds of precious metals, of rare-earth metals, of radioactive elements or isotopes 28 15 Sodium hydroxide (caustic soda); potassium hydroxide (caustic potash); peroxides of sodium or potassium. 28 15 12 In aqueous solution (soda lye or liquid soda) Commodity Code Description 28 15 12 00 In aqueous solution (soda lye or liquid soda)