Yeah, the colours were india ink and the black was calligraphy/artists ink.

After 24 hours, they were not coming off with water. Goof Off took them off nicely, but not with the "dampen the rag, rub" that I used for glue spots. I had to kind of flow it onto the surface using the rag as a dam, let it sit for 10-20 seconds, and then rub.

I've done a test of the dilute FW on some pine and also inside the control cavity, and it looked OK wet. I'll see how it comes up tomorrow when it's dry and then decide what to do next.

I'm still tempted to do the "piano black" thing over the whole guitar. It looks pretty good on the back when the light hits it, and I reckon it'll be better still with that tru-oil semi gloss look, but I'll definitely try another lighter stain or ink first and see how it goes.