@autumn there are things you can dip the tip in and itll "reactivate" it, i think its like a strong flux or something. try one of those wire cleaners maybe. or just flux and try putting some solder on it and then clean it again and so on. but if its really bad it probably means youre not wetting the tip often enough i think
@autumn yeah or youre running it too hot for too long. i do that too sometimes bc the tips just dont have enough thermal mass for some things and then i have to clean it immediately afterwards cuz it gets really dark and nasty