Remove Rust from a Cast Iron Skillet

Banish rust from your cast iron cookware for good. If you can remove rust but it always returns shortly after, follow these instructions.

Steps

 * 1)  Take a potato and cut the end of it off.  This will be your scouring pad.  Put Ajax or Comet Cleanser in the rusty cast iron cookware. Alternatively you can soak the pan in vinegar causing a chemical reaction that causes the rust to decompose. Use the potato to rub the cleanser around.  You will notice that the end of the potato changes and gets "slicker".  When it does this, slice a thin slice off the end of the potato that you have been using.
 * 2)  Rinse the skillet and put a bit more cleanser in the pan and scrub with the potato again.
 * 3)  Repeat the above process until the pan has all the rust gone.
 * 4)  Wash with liquid dish soap and water and rinse well. Then dry.
 * 5)  You can leave it like this if you are just going to deep fry in it.  But if you don't want it to stick, do the following steps.
 * 6)  Put a bit of oil or shortening about 1/4 in. deep (6 mm ) in the pot and rub onto the sides up to the top.
 * 7)  Put into an oven at a low temperature, say under 300 ºF (150 ºC) and cook the oil or shortening for several hours.
 * 8)  In the future when you use the pot or pan, if it sticks, repeat step 7 until it stops sticking.

Tips

 * NEVER use detergents or dish soaps when cleaning cast iron, they strip the seasoning off the surface. Use only hot water and a scrub brush.
 * After you're finished cooking with a cast skillet, heat it to medium heat, pour in a cup or so of HOT tap water and turn off the heat. The water hitting the hot iron removes or softens stuck-on food without removing the oil coat. After the pan is cooled, light use of a plastic scouring pad, a quick rinse and dry is all the skillet will need.
 * Vinegar will clean rust off of anything thats rusty just fill a big container with a solution of 2 parts vinegar to 1 part water. Place the item in the container and leave overnight, the next day the rust will be gone

Warnings

 * Rust consists of hydrated iron(III) oxides Fe2O3·nH2O, iron(III) oxide-hydroxide (FeO(OH), Fe(OH)3, non of which is soluble in vinegar, water, soapy water, AJAX or other detergents. Following the above instructions could lead to wasting food and materials.
 * Water is what causes the rusting in the first place. Vinegar (a weak acid) will also accelerate the corrosion. Using these chemicals could further damage the cookware. To prevent rust, re-season pans IMMEDIATELY after any serious scouring, cleaning with chemicals, or soaking.
 * Fe2+ + 2 H2O ⇌ Fe(OH)2 + 2 H+
 * Fe3+ + 3 H2O ⇌ Fe(OH)3 + 3 H+
 * The primary chemical justification for the use of vinegar (or any acid) in the removal of rust is not its solubility of the iron oxide, but due to the above redox reactions. By adding the acid, a supplier of H+ protons, it increases the concentration of H+ on the right side of the equation, and subsequently the reaction reverses to a more stable equilibrium.  As a result the iron oxides become iron and water.  It should be noted that using this method does remove the iron mass from the skillet which was rusted, but this amount is often negligible.  Similarly, don't leave the mixture in the skillet overnight, as vinegar does possess corrosive tendencies with iron (resulting in iron acetate), however under short-term diluted conditions, one need not worry.

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