Would there be a reason to not use a polyurethane
finish? I've had very good results with both water-based and oil-based poly finishes on interior wood surfaces, for structural stuff like trim and doors as well as for furniture pieces that get hard use. I prefer the water-based because it produces so little in the way of VOCs, odors, and toxic fumes, and it dries really quickly. You can't beat the soap and water
cleanup for your brushes
and spray equipment
, either. I used to think the oil-based poly was tougher, but I happened to bump into a MinWax company rep at a store who showed me some research
publications, saying that the water-based poly is actually harder after it is completely dry. But I still think the oil-based poly might be a good finish for your oily teak.
I like the poly for several reasons. After a first coat to seal and raise the grain for final sanding
, a second coat is usually sufficient for a piece that doesn't get hard use, like, say, door trim. If it's a table or bar top, I'll throw on a third or fourth coat, sanding
lightly in between to knock off any nibs that show up. (Seems like there's always one little bug doing the backstroke in the paint!) For final finish, a quick rub with 400 paper and then 0000 steel
wool, and it gleams like glass (even the bug spot!).
It is easy to spot-repair a poly-coated table. Sand out the damage, and re-apply just like the original, using 0000 steel
wool to blend the new into the old when you're done. It's quick and it's as good as new.
I have learned that polyurethane
tends to yellow with long-term UV exposure, so I wouldn't use it outside anywhere. For interior stuff that gets a little UV through openings, it's hard to say. An exterior spar/poly finish might be better. I have used that on exterior doors, but not any that I was able to observe over long periods. The exterior spar/poly that I have used has a yellow tint to it that changes the color of the wood, which is usually not desirable. On dark wood, you wouldn't notice too much. Regular poly is simply crystal clear, no color. I do hate to refinish exterior wood doors that have the old-fashioned varnish on them, all cracked and flaking from moisture and UV. That is a major PITA.
Good luck with the project! I'd like to hear what you decide to do and how it turns out.