It is a deep, ring-shaped pan with a tall tube in the centre. The tube is hollow, with no bottom on it, to allow hot air to pass through it like a chimney.
A tube pan allows for even cooking of the middle of cakes, and for taller cakes, because the space in the middle is unavailable for batter. The centre chimney gives angel food cake batter something to grip on to in the centre as it rises, allowing for better rising as it bakes in the oven. You also end up with a cake with more browned crust, as more of the cake batter is in contact with a surface of the pan.
The pans can be made of metal, non-stick metal or silicone, with fluted or flat sides. You can also buy disposable ones made of greaseproof corrugated paper. Aluminum ones will produce a lighter crust than dark coloured pans will.
Their sizes are categorized for sale according to how much volume they hold. Whenever a recipe calls for one instead by dimension (e.g. 10 inches / 25 cm), measure across the top, inside the rims.
You can buy single-piece ones, or two-piece ones with a removable bottom and tube to make it easier to get the cake out. In two-piece ones, the bottom and the tube are one piece; the outside piece has a rim on it that the bottom and tube part rest on.
The two-piece pans are better for angel food cakes and other foam-type cakes. The thicker batters usually don’t try to leak out the seams, and it’s easier to get them out when cooked. The solid, all one-piece pans are better for thinner batter cakes, so they won’t leak out through the seams. They are also better for yeast breads baked in a tube pan, because oven-spring on the yeast can push the two-piece pan apart.
Some tube pans have prongs extended upward from the top sides of the pan. The idea is that when the cake is done, you remove it from the oven but just leave the cake in the pan, and invert the pan to stand it up on the prongs to cool a bit first before attempting removal. The prongs thus act as legs, holding the cake up a bit in the air, allowing air to pass through under it to cool it. Some tube pans have a tube that is taller than the pan, and you invert the pan and stand it up on that tube.
You can also buy mini tube pans.
Do not grease tube pans for angel food, sponge, chiffon or any foam cakes: if you do, the batter won’t be able to grip onto the pan as it rises, and the fat will deflate the foam you’ve been working to build up.
Don’t use non-stick tube pans for angel food cakes. Not being able to get a grip on the sides of the pan to climb, the batter will collapse.
Tube pans existed as early as 1896. Fannie Merritt Farmer, in the 1896 edition of her “The Boston Cooking School Cookbook”, refers to them as “angel cake pans.” On page 417, she says a sponge cake “can be baked in an angel cake pan or deep narrow pan,” On page 418 she directs that Sunshine Cake be baked “in an angel cake pan” and on that same page, that Angel Cake be baked “in an unbuttered angel cake pan .”
In Australia, called a “ring tin.”