Got a temperature regulated solder iron, always had the temp set to 350C. Used the wet sponge after every solder job to clean the tip. Used a 60/40 rosin core 0.6mm solder. After week of use, when turning it on again I noticed the stock tip only had few areas where the solder would stick to. The areas were visible, they had dull metallic look, the rest areas were darker. Tried cleaning with wet sponge, made no difference. Finally had to use very fine sandpaper. After that no part of the tip was usable anymore. But the surface was metallic, not copper color so I don't think I sanded away all the tip cover. Is there any explanation for this?
Replaced the tip with a new one which came with the iron. Solder sticks to it well, but I don't know how long this one will last. Here are pictures of how a 60/40 solder looks on it (wanted to tin the tip). Very odd coloring. Does this give any explanation?
Not a professional, so didn't get an expensive quality solder station, but this one wasn't cheap either and had a iron holder, replaceable tips and temperature knob. The iron itself seems to work fine.