: I have recently aquired a S&G kayak that is in need of some serious TLC.
: I want to refinish it, however, I am not sure what was originally used on it.
: I am 90% sure the finish is varnish, but I have a feeling it might be
: polyurethane. Is there a definitive way to determine this? What would
: happen if I put spar varnish on it and it is, in fact, polyurethane? Any
: help would be greatly appreciated.
: Cheers,
: Brian

Hi Brian...
I think you can test for varnish/lacquer with acetone & a cotton ball, wet the cotton and hold it to the finish for a few minute's, If its not a synthetic finish some cotton should stick to the finish, Urethane finishes need paint remover to affect the finish. ( or sand paper.)
I would go to your favorite "Big Box" home improvement store and find the ONE GUY in the department that knows all about paint & ask. I like LOWES. They always have at least ONE pro in each part of the store.