Is my butane soldering iron's tip dead? (pic)
NEVER USE A FILE!!!

If you use a file on a (long life) soldering iron tip you will ruin it!

You are running the iron much too hot, turn it all the way down so the catalyst is only just glowing, if that's too cold turn it up slowly!!!

To get your tip back use tip tinner or a soft wire brush, such as brass to avoid damaging the tip.

Again, NEVER, EVER get a file anywhere near a non-shitty soldering iron.