YEAH, when you get a glob of solder to stick and when wiped away it leaves a layer of solder, that's a good tinning! It's hard and takes time but you could eventually get a good portion of the tip that way. I wouldn't say you need the whole tip either. Because of the pen style ergonomics I only hold it on a certain side anyways.

The grey solder is a sign of a "weak" joint but also having held the iron there too long is a cause of that too. You can turn a shiny joint grey too if you have to reheat it... I forget a wire occasionally.

I was thinking of film soldering at some point... just have to figure out a way to get a good vantage point and camera mounting.