Copper tip tinner - 96.5% tin / 3.0% silver / 0.5% copper
A mixture of solder powder and thermally stable, oxide-reducing compounds. Used to repair oxidized soldering tips for optimal performance and for extending the working life of new soldering tips.
Does not contain "sal ammoniac" / ammonium chloride
Brand name(s) : MG Chemicals

Features:
Oxidized tips are often dark gray in color
If the soldering tip is black - due to burned on flux or tip temperature is set beyond 800F it may be difficult to restore plating to the tip - carbonized residue may appear.
DO NOT USE EMERY CLOTH or SANDPAPER - warranty on the tip will be void
Tin the tip. Clean off the paste from tip surface with a cleaning sponge.
- Do not leave the paste on the tip indefinitely
** Do not use the chemical paste for purposes other than restoring of the soldering tip.

To clean or re-tin soldering tips
1. Bring the soldering iron to its standard operating temperature.
2. Roll or wipe the tip on the surface of the tip tinner. This should produce local melting.
3. Wipe tip on a wet sponge to remove potential post - tinning residues.