Making flies float

[Kent]

Yesterday we were fishing with Uintah fly rods up in the Uintahs. The fish would bite best if we could keep the fly floating on the surface. We tried blowing the flies dry before casting and had minimal success keeping the flies on the surface by doing that. Then I tried some liquid that Billy had. Instructions read to apply one or two drops to the fly and it would float for hours. Well, I applied two drops, and the fly almost floated for one cast. Does this stuff really work and if so how is it to be applied?
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