Brush a heavy coat of chemical stripper onto the teak furniture, using a paintbrush. Allow this to sit on the teak until the old finish begins to peel off.
Scrape the old finish off with a putty knife. Remove the old finish from hard-to-reach areas with steel wool. Wipe the teak furniture with a damp cloth to remove traces of the stripper.
Sand the entire piece of teak furniture with 120-grit sandpaper. Make sure all the old finish is removed. Wipe the furniture with a tackcloth and sand again with 220-grit sandpaper to create a smooth surface. Wipe with a tackcloth.
Brush a coat of sanding sealer onto the teak furniture. Allow it to dry and wipe off any excess with a cloth. Lightly sand with 220-grit sandpaper.
Wipe a coat of stain onto the teak furniture with a cloth. Allow the stain to absorb into the wood and wipe off the excess. Allow the stain to dry.
Brush a thin coat of polyurethane onto the teak furniture to seal the wood and protect it from moisture. Allow the polyurethane to dry and lightly sand the wood with 220-grit sandpaper. Brush a second thin coat of polyurethane onto the teak furniture and allow it to completely dry.