A week or more ago a PCB went though the solder machine, and for some strange reason the solder paste did not melt, now the paste has dried out, (we only just found out today) all the through-hole parts have been added (not me, say no more)
I noticed that when I tried to solder it with hot air that did not work, but if I use a tip of the soldering iron that works OK But it is a lot slower than hot air,
My question: can any chemical be added to the lead free paste so to sort of rejuvenate the paste?