Before you stain your furniture, sand it. Sanding smooths any rough grain and allows stains to penetrate evenly. Use a 220-grit sandpaper to sand the entire surface, sanding only in the direction of the grain. If you sand against the grain, you will create scratches that are difficult to get out. Use a tack cloth to wipe your furniture down after you are finished sanding. The tack cloth removes all the dust particles.
Clear stains are used only to provide added protection. They do not add color to your furniture, and they will not stop the natural graying process of teak. If you are one who appreciates the natural gray color, then use this type of stain.
Semi-transparent stains add some color to your furniture but not in a drastic way. This type of stain allows all the grain to show through, and your furniture will not turn gray.
Solid stains allow you to greatly alter the color of your furniture, and they are available in a wide variety of colors. This type of stain is more like paint but still allows you to see some of the wood grain.
Use a paintbrush that is designed for stains, and apply your stain with the grain of the wood. If you apply the stain in the opposite direction of the grain, it will leave an uneven appearance. Use soft, lint-free rags to wipe off excess stain, especially on vertical areas. Stains are thin and easily run if you apply them too heavily.
Use an oil-base stain for the best results. There are exterior water-base stains available, but they do not hold up as long.
If you stain your teak furniture, you will have to sand it multiple times to get it back to its natural state.