Sealing painted wood

[BMK]

I have a piece of furniture that I'd like to move out to the back patio / pool area. It's one of those cabinets with a hidden motorized TV lift inside. I've been wanting to put a TV out there for a while now, but there really isn't anywhere to mount it that makes sense. This cabinet is a good solution, and should also help protect the TV when not in use. Up til now it has been used inside (bedroom) and was not necessarily constructed to be an outdoor unit.
It will not be directly out in the elements...it will be undercover, and even during heavy rainstorms will feel very little direct water. It'll be covered with a waterproof cover when not in use (ordered) and will be stored indoors when the pool closes for the winter.
All that said, I'd like to protect it from the general moisture, spills, etc from being outside. It's made of oak, painted white. Is it possible to waterproof something like this after its already painted? What would be the best sealer for something like this? I first thought polyurethane, but read in several places that in this application it could yellow after a while. Any advice or recommendation is greatly appreciated. Thanks!

 

[Newdude]

My first reaction was to say clearcoat. (Poly) But then you mentioned the yellowing.... im pretty sure that happens only in sunlight. I have some indoor furniture and stairs going on 15 years still clear as day one. My table i built for the pool, which i stained and poly'd didnt last a year before yellowing and chipping. So stored for winter and under a cover most of the time you should be fine.

The other thought i had was to add a new coat of exterior paint. There are many options available and they can all be colored if need be. Stick with a premium brand and it will laugh at the occasional sunlight.

 

[crabboy]

I've used other products from General Finishes but not this one specifically, it is made for exterior projects. I just read that it may not be ideal for you since your piece is painted white.

You can also try Diamond Finish from KBS coatings. I used it on my fiberglass pool slide. It's tough stuff, but may be overkill. It's not cheap, not easy to put on, not easy to cleanup, but it's pretty tough.

I'd probably just run over it with an exterior paint, as suggested by @Newdude, it may be a bit thick, but should cover and protect it pretty good.