Instruct: Classify Amazon reviews into positive or negative sentiment
Query: bad tips

I was very excited to try this soldering iron for jewelry work. But, within 1-2 hours, the tip would no longer solder. I followed the instructions on how to tin the tip, and cleaned with wet sponge after each use.. But the tip turned black anyway and would not melt the solder anymore. I tried sanding the tip to remove the black, and that did not really work either. And, there is no way to find replacement tips. I went to Lowe's and Home Depot-- and nothing. But i liked it for the first hour or so it was working. :)