Teak is renowned among woodworkers for its high resistance to salt water and deterioration. It is for this reason that it is used on ship’s decks and makes a great material for residential entryway floors.
Teak wood has a high oil content, particularly Burmese teak, and this is what gives it its good deterioration resistance.
On the other hand, the same quality is what gives it poor adherence for finishes, since the wood’s natural oils prevent finishes like varnishes, urethanes and Swedish finishes from banding to the wood easily. That is why preparation of teak wood flooring before finishing is more time consuming than other woods.
There are a few viable finish options for teak flooring to choose from. All of them necessitate careful sanding before applying, using 80 grit sandpaper. The first finish is acid cure urethane, also called Swedish finish. They are very durable and do not need waxing, although they contain formaldehydes and are banned in some states.
Preparation includes “raking” the teak with rags dampened in denatured alcohol or lacquer thinner, in order to remove the excess oils from the wood surface. The first coat of finish is applied as soon as the raking solution has dried, and subsequent coats are applied straight away.
Burmese teak does not respond well to Swedish finishes; due to its high oil content, the finish can “lift” off the surface after a while. Because of its strong odor and limited availability (it is only sold to licensed contractors), Swedish finishes are not a preferred method for teak.
A better option is to use a good quality varnish, like Benjamin Moore. You’ll need good ventilation; open all the windows and doors you can and put a fan in or near an open door. Thin the first coat of varnish with gum turpentine, 3 pints to each gallon varnish. Don’t forget to plan ahead so you don’t literally paint yourself into a corner with no exit.
Using a 4 inch varnish brush, apply it along the width of the planks, don’t brush across them. Let the first coat dry 48 hours. Then lightly sand the entire floor, using 200 grit sandpaper to sand with the wood grain. This is to get off any dirt or small particles that are dried into the surface.
Before applying the next coat, vacuum the floor well of all sawdust. The second coat should be a mixture of 1 1/2 pints gum turpentine to each gallon varnish. Repeat the same drying and sanding procedure. The third coat will be straight varnish.
The other finish for teak floor is a penetrating oil, like tung oil (also called Chinawood oil) or teak oil. Use the furniture grade oil, not marine grade. This is the most natural method, and is more acceptable for homes where people with chemical sensitivities live, although penetrating oils do tend to trap dust more, so may not be good for homes with allergic people.
The other downside is that you will need to recoat every three to six months, particularly in high traffic areas like entry ways. You will also need to apply more coats, at least 3 to 6. Penetrating oils will darken the teak and give it pleasing hand rubbed look. They are used more for finishing furniture than floors, but can be useful for smaller floor areas.
Another method is to use a penetrating sealer along with wax. Minwax company, for example offers Dura-Seal Polyurethane and Dura-Finish. This is probably the least expensive and most cost effective method.