Acting or operating in two directions or with both motions; producing a twofold result.(adjective)
Gnu Collaboartive International Dictionary of English: licensed under The Code Project Open License (CPOL)
Use "double-acting" in a sentence
"With double-acting powder, some gas is released at room temperature when the powder is added to the batter or dough, but the majority of the gas is released in the heat of the oven."
"Baking powder is available as single-acting baking powder and as double-acting baking powder."
"You probably have double-acting baking powder in your pantry."