SF,
That's the reason I use Penetrol. It helps make the finish a little flexible, since I think the main constituent is fish oil. I'm not sure about that part.
I learned the process from an old-timer about 20 years ago, and used it with good success on a 53 Hatteras FBMY with miles of teak, including hand rails. The hand rails, which got a beating, got scratched occasionally, but I never saw a chip out of them. Anything that was enough to cause a chip either dented the teak or took a little chunk out.
It's about as durable as anything can be on a boat, I think. As for touch ups, I'm not sure I'd use fingernail polish. A little bottle of
varnish and thinner would probably be better.
I guess the bottom
line comes down to being careful with the finished product. I snivel and snarl at the boss and his guests when they scratch, ding and dent things on the big boat. Keeping a boat perfect, I guess, would mean putting it inside a bottle and never using it.
Good luck, and I hope I've helped a bit.
Cap'n Gary