When you are ready to fish, apply a covering of Weatherby's Dry Fly Floatant Powder to the fly, using the brush to work the floatant powder into the hackles, wings and other fly materials. The floatant powder will now protect the fly from the water, allowing it to float so you can dead drift or introduce movement to imitate the naturals you are competing with.
Once the fly starts to become wet, either through repeated casting, being drowned or hopefully by a take, dry the fly using a patch or cloth. You can then reapply Weatherby's Dry Fly Floatant Powder. We find that the second application can often last longer as the slightly damp fly materials allow the powder to adhere even better.
The following video shows how well water is repelled by Weatherby's Dry Fly Floatant Powder.