Acid and Copper Solution. 1  1. Ensure that the metal you are working with will rust. 2  2. Measure some hydrochloric acid into a plastic bottle. 3  3. Dissolve a bit of copper in the hydrochloric acid.  4. Dilute the copper and acid solution with 1  water. 5. Clean your steel or iron thoroughly.  6. Apply the acid 1  solution. 7. Allow the metal to  rust.
Quick Answer. Depending on size, potatoes should bake in the oven for around 50 minutes to 1 hour. Flipping the potatoes every 20 minutes during the baking process helps to ensure consistent baking throughout the entire potato. Continue Reading.
Rub each of the potatoes lightly with olive oil and, if desired, sprinkle with or roll in coarse salt. Place the potatoes directly on an oven rack in the center of the oven. Bake for 60 to 70 minutes, or until the potatoes are tender and a fork will easily pierce the largest potato when inserted into the center.ub each of the potatoes lightly with olive oil and, if desired, sprinkle with or roll in coarse salt. Place the potatoes directly on an oven rack in the center of the oven. Bake for 60 to 70 minutes, or until the potatoes are tender and a fork will easily pierce the largest potato when inserted into the center.