Teak oil is subject to evaporation, so to keep it looking nice, you have to reapply, which is easier than varnishing. There are cheap teak oils and more expensive ones, and of course, most people don't like to spend money, so they buy the cheap stuff. Interlux, for example, has a teak oil that is quite expensive, but it lasts a lot longer I have found. So, like most anything, you get what you pay for. Teak wood has natural oils in it and so you can't just varnish away with good results. The oil will lift the varnish in time, unless you do it properly. Properly means cleaning the teak well and priming it. There are some epoxy primers out there for varnish base coatings or you can go with Epiphanes's Teak Formulated varnish, but you must follow their directions for best results. I use this one a few of my boats and I love it, but it is a labor of love because you have to put on up to 8 or more coats of any varnish to make it look really nice. Another alternative is Sikkens Cetol which is also a teak sealer. They have had several generations of the stuff of which the first was too orangy colored. But now they have improved the color and the last formulation called something like Natural Teak is the only one of their products with a UV filter (or inhibitor). Most exterior varnishes have UV filters in them, but they are not permanent nor last for ever. You have to give it a recoat to replenish the UV inhibitor feature, but it is recommended to lightly sand your varnished teak annually and give it a coat anyway to keep it up. BTW, the Epiphane's teak varnish can be applied daily without sanding between coats, which makes it easier to do, but sometimes sanding now and then gives you a better look anyway. Back to Sikkens.....you apply a minimum of 3 coats of Sikkens Cetol - no more than one coat a day - and if you do this within the 2 week window, you don't have to sand between coats either. If you desire a high gloss finish (but Sikkens looks pretty good with the base formula), you can add their gloss finish on top of the first three coats. Sikkens is so easy and really lasts a long time and so if you are looking for something between oil and varnish, try Sikkens Cetol.
