I recently purchased a new soldering iron and read here that it is good practise to tin the tip before actually using it. As I turned on the iron and applied solder to the tip, I noticed the very top of the tip accepts solder perfectly fine, but the lower parts have solder just run off.
When the iron cooled back down, I noticed the top of the tip looked nice and shiny, whereas the lower parts of the tip have blackened. I am unable to remove the blackened color with a damp sponge.
The separation between the top of the tip and the blackened part is a distinct straight line, so I assume it is made of a different material or coating.
I am therefore wondering whether what I observe with this new tip is normal? I'd like to maintain this tip as well as possible, so am wondering whether it is good practise to store the tip like this (top part tinned, lower part blackened)? Or do I need to maintain it in a different way? I have read through the questions on tip maintenance but could not find anything similar to what I've observed here.
The soldering iron works perfectly fine, I am just worried about the blackening of the base of the tip.
The soldering iron is a TS100 and the tip is a B2. (https://www.amazon.de/gp/product/B072LR7DV6/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1)