This waterproofing powder works in heavy rain and even heavy wet snow. The trick is to apply the powder correctly. You must rub the powder into the feathers on your arrow. To do this place the powder into a sealable plastic baggie. Insert your fletched arrow and close the bag. Shake the powder onto the fletching and, starting with the first fletch, pull the feather back toward you separating the barbules of the feather. This allows the powder to get down between the feather's barbules. Now, shake more powder onto the fletchings and with your thumb and forefinger rub the powder into each fletching. When you've completed all of the feathers remove the arrow and knock it against your boot / shoe to remove any loose powder. Waterproofed this way your hunting arrows will remain waterproof for the entire season. Shooting your arrows and rubbing the fletching will remove the powder. Wash your hands with warm water and soap to remove powder from your hands.