Section 06 Products of the chemical or allied 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 Commodity Code Description 28 15 11 Solid 28 15 12 In aqueous solution (soda lye or liquid soda) 28 15 20 Potassium hydroxide (caustic potash) 28 15 30 Peroxides of sodium or potassium