Club Head Number Markings

[TigerdoomGF]

Hi, I have a very old set of Hogan irons but the numbers on the sole have faded over time. I say faded but the paint seems to have 'fell out' of the stamped number. Any ideas on how to restore these please?

 

[SteveJay]

Lots of stuff on you tube.....for example https://www.youtube.com/watch?v=sZ4hHZsNVj

 

[srixon 1]

Nail varnish.