Soldering iron tip is black and will not take solder: clean and tin it

Clean the tip and coat it with a little fresh solder right away. A tinned tip transfers heat well.

What the message means

Oxidation forms a black layer on a dry hot tip. Solder will not wet it, and heat does not move into the joint.

Fix it in this order

1. Wipe the tip on brass wool or a damp sponge.
2. Melt a little fresh solder onto it so it looks shiny.
3. Use the right temperature for the solder, and do not run it too hot.
4. Tin the tip again before you put the iron away.
5. Use tip tinner for a badly oxidised tip.
6. Do not file a plated tip, since the coating protects it.

If you see this, do this

Related

cold solder joint, loose contacts.

Last reviewed: November 2026. These are the usual causes and the order that finds them fastest. Test on your own board; clones and cables differ.