Some pancakes contain a raising agent (something that makes the pancake rise while cooking), usually baking powder, eggs, flour, and milk, which makes a thick batter. This batter is either spooned or poured onto a hot surface which is coated in cooking oil or melted butter. The batter spreads to make a cake about 1/4 or 1/3 inch (1 cm) thick. The raising agent makes bubbles rise to the uncooked side of the pancake, where now the pancake is ready to be flipped (turned over).