Final answer:
Baking potatoes without foil or fat results in a crispy skin due to the evaporation of moisture in the skin when exposed to high heat. The ideal temperature is around 400-425 degrees Fahrenheit to ensure a crispy exterior and a fluffy interior without burning or toughening the skin.
Step-by-step explanation:
When baking potatoes without using foil or fat, the skin typically becomes crispy. This happens because the dry heat of the oven causes moisture within the skin to evaporate, leaving a crispy texture. To achieve a crispy skin, it's important to bake the potato at a high temperature, generally around 400-425 degrees Fahrenheit (204-218 degrees Celsius). No additional fat is needed for the skin to crisp up; in fact, using fat can sometimes lead to a less desirable, soggy skin. While the outside becomes crispy, the inside of the potato should remain soft and fluffy. It's also crucial to not overbake the potato as it could lead to a tough skin, or worse, a burned skin if left unattended for too long.