Having grown up with the “spray” bug dopes and having tried all kinds of liquids, I still use nothing but paste type floatants………… just don’t ever place floatant on a fly that is damp…………you will seal the moisture in.
Make sure a damp fly is thoroughly dry before using any kind of bug dope.
I dry mine by pinching in the fold of a cotton T shirt or dry napkin in THREE places. By the time you pinch in the third different fold, you will have removed most of the water.
At this point, brush on any of a number of the new powdered dessicants, allow the powder to work for around 15 seconds, blow the powder off the fly, then come back with your final treatment of a fresh light coating of a paste. The dessicants will pull the last remaining dampness out completely but you still need the paste to “seal” the fly from water absorption.
The fly should now be as dry as it was when first tied on. Re-coat with your favorite paste floatant.
Some fishermen use only the powdered dessicant, then return to fishing the dry fly without re-applying the paste. The fly will float well for a very short while, then sink worse than it did before. The reason is that the dessicant also removed the remaining paste floatant that was originally on the fly. If you follow my steps above, your fly will float well.