No, tin foil (or aluminum foil) is not flammable. Aluminum itself has a very high melting point, around 1,220°F (660°C), which makes it resistant to catching fire. In fact, it's commonly used in cooking, grilling, and food storage because it can withstand high temperatures without burning or igniting.

However, there are a few things to keep in mind:

1. Thin Foil in Direct Flames: While aluminum foil won't catch fire, it can become very hot and may burn or melt if exposed to a direct flame for an extended period, such as from a gas flame or open fire. If the foil is very thin, it might also warp or burn through if it's in direct contact with intense heat.

2. Burning Foods Inside: If you have food wrapped in aluminum foil and it burns, it’s the food that is burning, not the foil. The foil itself won’t catch fire, but it can get very hot and should be handled carefully.

3. Electricity Hazards: If aluminum foil comes in contact with electrical components (like the heating elements in an oven), it can potentially cause a short circuit or even sparks, so it's important not to use foil improperly in these situations.

In general, aluminum foil is safe to use in most cooking and grilling situations, but always make sure it’s not exposed to flames for prolonged periods.