Silicone caulking is not appropriate for any surface that requires a coat of paint. When acrylic latex and oil-based paints are applied directly over silicone, shedding rapidly ensues. Unfortunately, many do-it-yourselfers use non-paintable silicone caulking to seal cracks and seams, because they don't know any better. If you are confronted with a surface marred with silicone caulking, you will need to apply a special type of primer, or you will have no chance at paint adhesion.
Wash exterior silicone caulking, using a pressure washer. Use damp rags if the caulking is located indoors. Wait two to four hours for the caulking and surrounding surfaces to dry.
Coat the silicone caulking with an oil-based primer, formulated for compatibility with water-based latex paints. Apply the primer, using a paintbrush, engineered for use with oil paints. Wait two hours for the primed silicone to dry.
Wash the oil-based primer from the paintbrush with white spirit. Do not use water, as this will destroy the brush.
Coat the primed silicone caulking with paint, using a paintbrush engineered for use with water-based paints. Use acrylic latex paint on exterior caulking. Use a satin or semigloss latex paint if the caulking is located indoors.
Wash the paint from the paintbrush with water. Do not use white spirit, as this will destroy the brush.
Acrylic caulking is appropriate for sealing cracks and seams in surfaces that require a coat of paint.
Most oil-based primers will reject latex paint. Be sure to read the label before you buy to ensure that the oil-based primer you choose will work with water-based latex.