On @Andyjr1515's recommendation I've used calligraphy ink with great results. I just wiped on with a household kitchen sponge, one of those with a scourer on the back. It's water based so can be easily watered down to achieve a lighter shade, and to a degree mistakes can be wiped off with a damp cloth.
Can be oil finished, lacquered or waxed over once dry to any degree of matt, satin or gloss.
Here's an old Kay neck through that I stained the body wings on then lacquered over.