Aluminum Foil No-Nos
What not to do with aluminum foil
You want to keep your oven sparkling clean so you protect it by adding aluminum foil on racks, under food as it cooks and down on the oven floor where food drops and burns to a crisp. Instead of helping, you’re hurting your oven. Foil placed on the oven floor reflects and intensifies heat which can cause the bake element to burn out prematurely. Foil placed under foods on the racks is bad because it traps heat in the bottom of the oven, keeping it from circulating and reaching the heat sensor near the top.
Severe overheating is possible, and besides damaging the bake element, it could also affect insulation in the oven wall and discolor or even crack oven-door glass. By disrupting temperatures and air circulation, aluminum foil messes up cooking times too. A quickie clean just isn’t worth it.