.... I find a bamboo skewer perfect for scratching away deposits or blobs of flux , the wood is a little softer than the pcb material ,so does no damage to the undelying surface , I remove as much as I can by scraping first , I then use a qtip moistened with iso to swab the areas , I try to avoid spreading it around , so I wipe with the qtip , rotate it 90 degrees , wipe again , rotate etc .
Its very easy to flood the area with iso ,disolve all the flux and end up with a microthin layer covering the entire board when it all dries out again .
