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.
Step 4. Place potatoes directly on the oven rack, and bake at 375 degrees for 45 minutes for medium to large potatoes. Turn the potatoes over halfway through the baking time to ensure even crispness and avoid darkening on one side. Step 5. Remove from the oven when baking time ends and cut or squish the top of the potato open.