How old are they, how long have they been out and have you used any products on it before? Teak is a greasy/fatty wood, that's why it's used for exterior purposes.
My mom painted her table with oil paint (the type to make paintings with), because she did not want to use chemicals to get the oil out she'd been treating het furniture with for years.

They are 7 years old and I have not used any products on them.

Then clean it, first with soap, rinse with water, leave to dry. Clean thoroughly with thinner, sand down, clean again, leave to dry. Paint with primer, dry, sand lightly, paint in color.

There is a lot of oil in teak. You will need special paint to avoid "bubbles" as "normal" paint usually reacts to the teak oil. Personally I would never paint teak. I would get the color from something else :)

that's an even better idea