Galoots

I'm making a hinged rule out of cherry, and ran into a problem while
punching the numbers. After punching the number 2, I noticed there was
some dirt in the bottom of the number, so I cleaned all my punches
with a brass brush. Then I punched the number 3 and realized the
brushing had smeared dirt all over the punch. Now I have a rule with a
number 3 that is almost black while the others are not. The dirt seems
to be mixed with grease (perhaps from the brass brush) and doesn't
what to come out.

So here's my question, how can I darken all the numbers to make them match?

The numbers are punched into the face grain of cherry, about 1/32"
deep. I could plane all the numbers away, but having darkened numbers
isn't a bad thing.

Thank you,
Chris