How do you make homemade lye?

How do you make lye?

• Lye is sodium hydroxide. Wikipedia: http://en.wikipedia.org/wiki/Sodium_hydroxide

• Answer:

  Somewhat practical way to make lye at home is to put baking soda in a very heat-resistant pan and then put that either through an oven self-cleaning cycle or an hour or two at ~500 degrees F.  This drives off carbon dioxide from the sodium bicarbonate, turning it into sodium hydroxide.  If you take this baked soda and dissolve it in water it will be functionally equivalent to a lye solution. Industrially lye is made using variants of the chlor-alkali process where very concentrated solutions of sodium chloride have a current applied to them, producing chlorine at the anode and hydrogen gas at the cathode.  Since H+ ions and Cl- ions, once reduced and oxidized (respectively) are consumed in the reaction, the remaining sodium cations are paired with hydroxy anions, producing sodium hydroxide. In the old days before the chlor-alkali process people tended to use leached wood ashes.