Sharpie Industrial Fine Marker
Sharpie is a great way to colour and blacken your Stamped makes. Simply Apply, leave to dry and remove the excess. Though Sharpie ink will become permanent after setting, it can be erased. 3 or 4 strokes of a dry erase marker will remove Sharpie ink. WD-40 will work moderately well on recent markings if dry-erase markers are not available. Also Crayola's "Colour Wonder" mess-free markers have also been effective in removing Sharpie ink that has been dried for several days.
You can use Nail Varnish Remover also to remove excess ink on your stamping blanks.