Impregnation is process of applying a coating or layers of chemically stable liquids to porous surfaces (like casting) or objects with inherent voids (like motor coils) to prevent accumulation of undesired elements like dust, dirt, chemicals or water. Impregnation of objects improves its physical properties and also tends to improve overall parameters of the equipmentcomponent wherein use. For Ex. a varnish impregnated coil improves the overall insulation resistance of the motor and hence the life of the motor is improved.