Acetone man I thought that stuff ate everything. I'll have to give it a try I hate the white residue 
Acetone works fine - I use a toothbrush and scrub the 'fluxed' area vigorously then (using the toothbrush) I sweep the excess liquid (now laden with disolved flux) off the edge of the board with fast, repeated sweeping motions - it dries very quickly and doesn't affect screen printed legends etc.
