Acoustic Guitar Construction

Actually, I've already dyed - the neck on the parlor guitar, black.
Question - I have a small area that needs to be touched up with the dye - and of course it is next to some lighter wood, the headplate.

Will a coat of shellac on the neighboring areas protect them for any errant but inevitable dye drops? Just looking for some way to protect the lighter wood. Any ideas welcomed!!

I do not use dye, but some of them are alcohol based, and I fear the dye could bleed into the shellac.

Yeah, me too.

Maybe seal it with shellac or something compatible with your final finish the tape it off.

That's gonna have to do it, I think. That, plus me being very careful with the touch-up. :-)

This might sound stupid but a black magic marker would solve it

Black Magic markers usually have a pruple blue tint, not really pure black and also a bit of sheen.