Using a 35W constant temperature electric iron, heated iron head black, with rosin, then solder, solder coating is not on, have the ball dropped, where operation mistake, and ask whether the new iron head sanded ah?
The new iron head needs polishing.
Prepare a small piece of sand paper and soldering tin, insert the soldering iron into the power supply, and then heat it, then rub it on the sand paper and hang the tin. Tin can be polished until the iron head is fully plated with tin. Unplug the power. It's OK to use it later. Of course, when the iron is not in use, you must unplug the power in time, not long heating, easy to burn the iron head, but also need to be re processed.
The new iron head has an oxide layer, with a file away, exposed copper surface smooth, heating and sticky rosin, to the temperature after hanging tin, usually used frequently with rosin, keep tip oxidation, or tin melting difficult, not easy to stick tin.
