Having refinished and repaired
varnish, poly and other finishes over the years I can tell you that no two varnishes are the same. Add to that aging, UV, moisture, age and all bets are off as to spot matching the existing
varnish.
One trick is to get a variety of stains, in small cans, add it to the varnish your using (try using a varnish that isn't already tinted) and do some test patches on a suitable piece of
teak, just buy a piece at a
marine teak supply. You can do several test patches on the donor piece and then hold it up to the existing. This way you can see how well your matched before actually applying it to the existing piece.
Just remember, you'l probably have to do several coats to match the thickness of the existing piece, so usually go slightly lighter than the
current color since multiple coats will darken the shade.
I've fixed ancient furniture this way, just remember, it will also age eventually, most varnishes darken with age unless exposed to UV on a regular basis, in which case it will lighten, so take this into account before doing the
repair. If it were me, I'd just sand the whole thing and do it over.
Don't ever put a can of varnish on a plane, it will explode open whether in checked or carry on. It's considered a hazmat material. Hmmm, what shade would your clothes in that bag be with Epifanes Clear Varnish?
Used to be a million mile flyer in my previous life, I've seen many strange things come down the luggage line.