Putting a cardboard pizza box into a hot oven should be avoided entirely. The short answer is a definitive no. This shortcut introduces significant safety risks and guarantees a poor culinary outcome. Pizza packaging materials are not designed to withstand the temperatures required for cooking or reheating, creating a serious fire hazard and compromising food quality.
The Immediate Fire Hazard
Cardboard is a combustible material, and its ignition point falls within the normal operating range of most home ovens. The auto-ignition temperature for typical corrugated cardboard is generally between 400°F and 475°F. Since many pizzas are cooked or reheated around 400°F to 425°F, the margin for safety is extremely narrow.
The risk is compounded by residual grease and oil soaked into the cardboard from the pizza. This grease acts as an accelerant, which can lower the effective temperature required for the material to catch fire. Even if the oven is set below the ignition point, hot spots or prolonged exposure can push the material into the danger zone. Placing a flammable item in an enclosed, high-heat environment creates an unpredictable fire risk.
Health and Chemical Concerns
Beyond the danger of combustion, heating non-food-grade cardboard introduces chemical risks. Pizza boxes often contain inks, adhesives, and specialized coatings that are not intended to be heated. When exposed to high oven temperatures, the glues can melt, and the printing inks can vaporize, releasing fumes into the oven cavity.
Many pizza boxes are treated with anti-grease coatings to prevent oil from soaking through. These coatings frequently contain Per- and Polyfluoroalkyl Substances (PFAS), often referred to as “forever chemicals.” Heat accelerates the transfer of these chemicals directly into the food. These substances can impart an unpleasant odor and flavor to the pizza, and they are not safe for consumption when heated.
Why Your Pizza Will Taste Bad
Using cardboard as a cooking surface guarantees a disappointing result for the pizza itself. Cardboard is an effective insulator, which is why it helps keep a delivered pizza warm. When placed in the oven, this insulating property prevents the necessary heat from reaching the bottom of the crust.
The lack of direct heat transfer results in a soggy, undercooked crust, even if the toppings appear melted. Moisture released from the pizza during reheating becomes trapped between the crust and the cardboard, steaming the dough instead of crisping it. To ensure a crisp bottom crust and a safe reheating process, transfer the pizza to a metal baking sheet, a pizza stone, or place it directly on the oven rack.