The best way to ensure a soldering iron tip or desoldering nozzle has the proper wetting characteristics is to ensure the proper formation of the alloy layer in the iron plating . To do this, we recommend the use of Hakko FS-100 Tip Polish as doing so provides the mild flux component to the tip and does not leave any corrosive materials on the tip / nozzle 

Below is the proper process on how to restore your soldering iron tip or desoldering nozzle .

1. Set the soldering/desoldering station to a temperature of 300°C (approximately  575°F)
2. Add a flux cored wire solder that will be used in your applications  or use the HAKKO FS-100 Tip Polish 
3. Remove the solder using a damp sponge. The sponge should be made damp using de-ionized  or distilled water only to prevent any mineral contamination on the surface of the tip/ nozzle . If there is carbonized flux or other residues on the surface of the tip/nozzle that do not wipe off cleanly with the sponge, use the FT-700 Tip Polisher.
4. Repeat the steps 2 and 3 above for a total of 3 to 5 times.
5. The last step involves adding solder for re tinning . This is the final application of the flux cored wire solder that will be used in the process, or you may use the HAKKO FS-100 Tip Polish
6. Let the solder remain on the tip undisturbed for 10 minutes
7. Apply a fresh amount of flux cored wire solder or HAKKO FS-100 Tip Polish and remove the excess solder.
8. Allow the tip/nozzle to cool
9. Clean any flux residues off the tip/nozzle using IPA.

This  procedure is only to be performed as needed to restore the wetting characteristic of your tip/nozzle surface. If a tip/nozzle is properly maintained there should be no need to perform this procedure .