The idea of liquid-based floatants is to dunk your fly in a bottle of the stuff, before shaking vigorously to ensure a complete coating. Any excess liquid is easily removed by a couple of false casts, which also dries the fly off. As mentioned earlier, in fairness, liquid floatants render the whole fly waterproof, which is all well and good where buoyancy is the order of the day. I find such an application handy when tripping bushy wets through wave tops on blustery days. They’re also useful for the likes of Muddler patterns, or deer hair Sedges, especially where a fly that creates disturbance is required and needs to stay afloat for long periods. Some liquids come with a convenient brush – the idea being that floatant can now be applied to only a certain part of a fly. However, being ultra fine in their consistency, liquids tend to bleed into the remainder of the fly, no matter how diligently you attempt to apply the said liquid. For this reason, try to refrain from using them on any flies that are designed to sit in the surface film, or partially below it.