defining contrast in cnc carving

[Britannicus1]

I've had a go at engraving a plaque and I'm quite happy with the result - EXCEPT - I want to make more contrast between my engraved image and the plain plywood I cut this on.

I've tried a few experiments

1/ I first tried cutting with a masking film and then spray painted, but the pain bled along the groove

2/ Next I tried using a paint line along grooves - messy and unsatisfactory

3/ I did try spraying the whole surface black an cutting through - but this gave me a light line against dark and I'm looking for the reverse really

What treatments do you use to get a pleasing finish on your CNC work - I'm planning on working on light oak at the moment . any tips on how to get multiple colours into the finished product ?