Zap-A-Gap

The waterproof formula really does hold up after a full day of wet wading. A tiny drop on the thread wraps and my nymphs survived rocks and repeated strikes without unraveling.

My flies have held up way better since I started putting a drop of this on the thread wraps before the head cement. It's waterproof so I'm not worried about it breaking down after a few hours in the river.

Used this to reinforce the thread wraps on a batch of nymphs and it soaked in clean without leaving a chalky residue. Tied a few dozen and none have come apart after a full day of bouncing off rocks. The waterproof part actually held up in the current, which is more than I can say for the last glue