Is conformal coating waterproof?

While conformal coatings can offer a moisture resistant layer of protection, most cannot be considered waterproof. Even if applied heavily, most coatings are semi-permeable, so allow some amount of moisture through. Conformal coating can, however, prevent current leakage or corrosion due to ambient moisture. To truly waterproof electronics, you either need gasketing to seal the electronics within the packaging or cover the electronics with a waterproof encapsulant or potting compound.