I always hand brush future. I use a soft flat 1/2" brush (made by Humbrol). Decant the future into a film canister, which is secured to a base, with double sided tape, (anything will do, just to stop you knocking it over). Dip the brush into the future, the important bit is to scrape most of the future off, on the edge of the film canister, now you see why it needs securing to a base. The amount on the brush will cover about 1/2-2/3 of the wing of a 1/48 scale P47. Future (Klear in the UK) is self levelling, all you have to do to achieve a flawless finish is to take your time. be carefull at edges and detail, the Future will tend to pool but just soak it up with the brush, like blotting paper. If you have just loaded the brush with Future, then dry it off a bit first (so theres room to soak up the pooled stuff), on a paper towel.
Take a look here at my Tamiya Dewoitine D.520, it was hand painted with Future, here:
http://groups.msn.com/_Secure/0SQD8Av8U*PIEdKoIWUH7zz4IfdbhS5KSpgVs475BZnIlGKw7pWWjLeDyH7rr5Q!htjO1GuKMQ9NFt0hprGnHfp829s0s2!!MScIUcezVncUrWPnhaX*5yg/Dewo-250-a.jpg?dc=4675404503865895347
Mal
PS I have found that to air brush Future you need high pressure