I am using low gauge magnet wire, wrapped in cigarette paper soaked in GE varnish, as pegs to solder to inside of a cryostat.
However, I have found it nearly impossible to solder to the magnet wire, at least not at low temperature. I strip the insulation off with a razor blade, apply flux, then try to solder at 400 degrees F. That never works.
If I up the temperature to 450 degrees F, the wire whets as expected, but the insulation changes colors (i.e. it gets darker). It seems to still be insulating, but I am not sure if any harm was done. Additionally, I would prefer not to solder at such a high temperature, as some of the things I need to solder are very fragile and should not be soldered at temperatures greater than 400 degrees F.
I would have thought that the "tinning" process I just describes above would make it possible to solder at 400 degrees F, but that still won't work. The tinned solder wont melt until it gets hotter, despite the fact that fresh solder will melt on the iron's tip.
Am I doing anything obviously wrong here? Does anyone have advice on doing apparently impossible soldering jobs?