For the
record, it's resorcinol (short for resorcinol formaldehyde).
But moving on from there, the
varnish method makes a lot of sense - afterall, if the plugs are correctly sized, they are hammered in nice and firm, so its just a matter of sealing them.
As to treatment, with modern decks (yes, I know we are talking toe-rails here, but ...) at least (read 12mm thick or worse), I am not an advocate of leaving
teak to
weather. 'Weathering' means
washing over the side.
On our toerails and decks, we use Semco. The Semco washes over the side (takes up to three years to do it mind you) rather than the precious
teak. We do a 50' fully
teak deck, plus
cockpit once every one to two years, in around 5 man-hours, if that, and the decks still look like new after 9 years.