Red Powder Logwood Trap Dye turns traps black.  Approximately 1 bag is needed for every 5 gallons of water.  Directions are included with each bag.  Sold in 1 pound bags.
 
Black Powder Trap Dye turns traps a dark blue-black.  Each 10 gallons of water requires approximately 1 bag of dye.  Directions for use are written on the bag.  Sold in 1 pound bags.