The produce of porcelain insulator
Porcelain insulators must be manufactured by wet process. All the exposed porcelain insulators surface must be covered with a vitrified type hard, smooth, shiny and impervious to moisture compression; that allows, through the natural wash of rainwater, easily kept free of dust or residual dirt caused by environmental pollution.
The total surface of the insulator
, except the burning surface, must be enamelled. The total area of the porcelain insulator must be free of imperfections.
The porcelain used porosities not have to file; must be of high dielectric strength, high mechanical strength, chemically inert and high melting point.
They will be rejected with the isolators failures vitrified; independent if they have been retouched with enamel, subject to a new burning, or touched up with paint.