Clean the sink and drainboards thoroughly with an abrasive cleanser using a heavy-duty cleaning sponge. Don't worry about abrading the surface -- the surface needs to be slightly rough to help the epoxy adhere. If limescale or rust staining is on the sink, also use a limescale remover. Rinse the sink well, so that no cleanser residue remains and allow it to dry completely.
Sand the surface of the basin and drainboards with a 120-grit sandpaper; some tub and tile epoxies don't require this, so check the label on your product. Sanding may also be unnecessary if the surface is already dull.
Mask the edges of the drainboards with painter's tape to protect the counter top.
Mix the epoxy and hardener as directed. With a 1-inch wide foam brush, paint the edges of the drainboards and the areas around the fixtures. If the drainboards have ridges, paint them with a 3-inch wide foam brush.
Paint the rest of the sink with a 6-inch roller, using long, even strokes. Touch up any missed areas with a foam brush.
Allow the sink to cure for at least 36 hours before using it.