Don’t say we didn’t warn you

Your oven is really great at a lot of things: roasting, braising, baking, broiling. There are a million things you can do with it, from warming plates on low, to making super easy all-in-one sheet pan suppers, to reheating prepared or frozen foods. You can use it as a dehydrator, pizza oven, and even to keep your canning jars warm before filling for preserving projects.

But there are still some things that you shouldn’t put into your oven, or try to do with it, for safety's sake. Here are the top five no-fly-zone oven dangers.

1. Unprotected food and food debris

The Danger: Fire

All food that goes into your oven should either be in or on an appropriate vessel, or if something calls for putting a food item directly on the oven rack, there should be a protective pan or something underneath in case of drips, spills, or leakage. Food, especially greasy or sugary food, can easily start a fire in your oven. If it is allowed to fall to the bottom it will burn and smoke and affect the flavor of whatever you are cooking (in a best-case scenario) or could get onto the element or catch the gas flame and ignite (in a worst case). If you notice the smell of something burning in your oven as you preheat, check to see if you have food debris, and be sure to clean it properly before continuing with your recipe.

2. Plastic

The Danger: Harmful chemicals

There is no such thing as a safe plastic to use in your oven, no matter how low the heat setting. Doesn’t matter if it is a super durable plastic item like a Tupperware or Rubbermaid container, or the disposable deli container your leftovers are in, or a plastic wrap like Saran: Plastic is always going to be a non-starter for your oven. And yes, I know some of your frozen meals come in plastic, but those are commercial grade specially designed and treated trays, and not available to the home cook. And no, you cannot re-use them, since once they have fulfilled their initial purpose, the plastic has degraded, so it will not be safe for a second go-around. Even if the plastic doesn’t melt creating an oven disaster, it can leech harmful chemicals into your food as it heats up. Stick with appropriate oven-safe materials at all times. (Note that silicone items designed for cooking—different than plastic—are fine.)

3. Empty glassware, cold glassware, damaged glassware, and non-tempered glassware

The Danger: Shattered glass

Of course, you can use your glass casserole dishes and pie plates safely in your oven. However, you have to be careful of thermal shock. This is when the difference in temperature between the glass item in question is so different from the temp of the oven that it shocks the glass, which can cause cracking or even exploding! Only use glassware that is specifically designed for oven use, is full of food, has no cracks or chips making it vulnerable, and is as close to room temperature as possible. Do not put straight from the freezer or fridge into your hot oven. Thaw frozen dishes for at least 24-36 hours in the fridge, and then let sit at room temp for at least an hour before putting in the oven. If you don’t know if a vessel is oven safe, err on the side of caution and use something else.

4. Wax paper, paper towels, or other paper products

The Danger: Melting and fire

Wax paper will melt and taint the food you are covering with it, and paper towels, plates, or bowls are not designed to be heatproof at those levels and can burn. The only “paper” exception to this rule is parchment paper, which is designed for baking use and is safe for all of your cooking projects.

5. Wet or damp towels, potholders, or oven mitts

The Danger: Burns

Only use completely dry items to handle things that are going in and out of your oven, including moving racks in and out, turning or shifting vessels or trays, or retrieving hot items. Any water in your towel or oven mitt will instantly turn to steam in the heat of the oven and can result in burns.