Beautiful work. You are a master joiner! Teak is rugged and best left alone or be a slave to varnish
and for slat work this is a major hassle. Leave it alone!
I built a similar seat years ago (portable) and removed it / stopped using it because I don't sit at the helm
using the autopilot
or just stand and helm
for short stints. We have a large flat aft section in the cockpit
which is great for lying about. And the lazarettes are back there too, so covering them was not the greatest idea. See attached.
I would not worry about the end grain, but surely if you lightly oil the teak, it should perhaps lengthen its service
If these are not permanently attached stow them to cut down on weather
and UV exposure when not in use. Or provide covers. But you'll get years of good use. They are beautfully built!
teak is covered with cushions
when where aboard but exposed the rest of the time. The OEM slat work lasted about 20 years under those conditions but has become weak and shabby from wear and cleaning
after about 15 years. Last year I ripped it out and redid the whole thing. YIKES what a project
I figure this work will out last me though so I am not terribly concerned.
Avoid harsh cleaners and stiff brush scrubbing. It will pull out the soft parts
off the surface of the wood. Teak loves salt water