I've run into problems soldering up some long-stored kits (10-20 years old) that may be due to my ineptitude, but could also be due to a bad choice of soldering iron temperature. The problems range from soldering simply doesn't work-no solder blob forms at the board surface, to that problem plus a big burned spot on the surface and a loose copper trace peeling off the board. Sometimes the metal spot around the hole in the surface disappears completely. Could it be due to the age of the board, or lower standards of manufacture? Could I need a hotter iron? The one I'm using goes only to 480˚F. Some authoritative sources say I should be working at 600˚; others, equally authoritative, claim I should work at 480˚ or lower. I also haven't been using flux. So is it me, or the circuit boards? Fortunately, I'm using the construction of these old kits to sort out my technique; if they work, great. If they don't, I salvage the parts and go on to the next kit.