Kester 44 here, 60/40. Kester flux pens for reflow, sometimes I use No-Corrode (sp?) solder paste, not much though...and I'll probably catch flack for this, but brake cleaner is the best flux remover I've ever used. I had some old boards that were trash, and I experimented with it, flushing the board and scrubbing it with a fairly stiff toothbrush. Talk about clean! And, I have yet to see it lift a trace or harm a board. Q-tips and a little brake cleaner to soften it up, then isopropyl or acetone for finishing up. Just do it out in the open air. Nasty stuff, I sure don't want to be breathing it.