India ink

I have read and seen modelers use it for oil stains, grease stains, and as a very black wash. And I agree about the adding of soap to break the surface tension of the ink.

If ya tyri dont forget to add a small drop of soap to it to break the surface tension or ya wont be able to wipe up the excess

I have a friend who used it extensively for weathering on armor and dioramas. ("Used" as opposed to "Uses" because he doesn't build any more)

I have some that Im going to be experimenting with. But I havent used it yet.

I think I'm experiencing deja vu... I swear I've seen this post in the "Tools" forum...

Anyway, not me yet but other modellers have. I've read in FSM of a guy who did the checkered nose on his P-47 model by lining and filling in the black squares with a tech pen using india ink (awesome job, I may add). Some also use it to highlight recessed panel lines, again with a tech pen. I'm sure others have come up with creative ways in using india ink and will post soon. Hope this helps.