When Tattoos Oxidise, Why So Hard to Remove if Black the Easiest Colour?

Hi Nightshift.  We have not had a problem removing tattoos that oxidize darker.  You are correct that if the easiest color is black and the tattoo oxidizes to black that it should still be easily removable.  This has been our experience.  

The colors that are more challenging to remove when the tattoo oxidizes is a pale blue or grey as well as orange.  

The lasers can break the black ink tattoos more easily than the other colors.  Also, it takes less sessions to remove black ink tattoos.

I am not sure if your tattoo is already gray and more difficult to treat.  You are correct that black tattoos are the easiest to treat.  Please find an experienced physician in your area to treat your tattoo.  Multicolored or oxidized grey or blue tattoos are much harder to treat.